JP6400187B2 - Refrigeration cycle equipment - Google Patents

Description

  The present invention relates to a refrigeration cycle apparatus having an inverter-driven refrigerant compressor.

  Conventionally, as a refrigeration cycle apparatus having an inverter-driven refrigerant compressor, a refrigeration cycle apparatus provided with a dedicated cooling circuit for cooling an inverter heat radiating portion with a refrigerant is known (for example, Patent Document 1). . Also, a refrigeration cycle apparatus is known that can adjust the flow rate of the refrigerant that cools the inverter by controlling the expansion means (for example, Patent Document 2).

JP 2003-021406 A JP 2008-057875 A

  However, in the refrigeration cycle apparatuses of Patent Documents 1 and 2, since the refrigerant that has cooled the inverter joins with the refrigerant that flows through the refrigeration cycle and is sucked into the refrigerant compressor, the temperature of the refrigerant sucked into the refrigerant compressor is reduced by the inverter. It depends on the temperature of the cooled refrigerant. Therefore, in the refrigeration cycle apparatuses of Patent Documents 1 and 2, the refrigerant sucked into the refrigerant compressor becomes a liquid refrigerant or a gas refrigerant having a high degree of superheat, and a stable operation state of the refrigerant compressor may not be ensured. From the above, the refrigeration cycle apparatuses of Patent Documents 1 and 2 have a problem that the reliability of the refrigerant compressor and the inverter and the efficient operation of the refrigeration cycle apparatus may not be ensured.

  The present invention has been made to solve the above-described problems, and an object thereof is to ensure the reliability of the refrigerant compressor and the inverter and the efficient operation of the refrigeration cycle apparatus.

In the refrigeration cycle apparatus according to the present invention, a refrigerant compressor having a compression mechanism unit and an electric motor, a condenser, a first pressure reducing device, and a first cooler are connected via a refrigerant pipe, A refrigeration cycle for circulating a refrigerant, an inverter for supplying AC power to the electric motor, a refrigerant pipe between the condenser and the first pressure reducing device, and the first cooler and the refrigerant compressor A bypass refrigerant pipe connected to the refrigerant pipe between the second refrigerant decompression device, a second decompression device arranged in the bypass refrigerant piping, and the bypass refrigerant piping on the outlet side of the second decompression device, the inverter A second cooler that cools the first decompressor, a first controller that adjusts the opening of the first decompressor, and a second controller that controls the opening of the second decompressor, The first control unit is configured to control an opening degree of the first decompression device. Only by settling, is for controlling the degree of superheat of the refrigeration cycle in the range of the first target value, the opening adjustment of the first pressure reducing device, the superheat degree of a control quantity the freezing cycle When the upper limit value of the first target value is exceeded, the opening of the first pressure reducing device, which is an operation amount, is increased, and the degree of superheat of the refrigeration cycle, which is a control amount, is the lower limit of the first target value. When the value is less than or equal to the value, the operation is performed by lowering the opening of the first decompression device, which is the manipulated variable, and the second control unit adjusts the opening of the second decompression device, The cooling temperature of the second cooler is controlled within the range of the second target value.

  According to the present invention, the degree of superheat of the refrigeration cycle apparatus can be controlled within a predetermined first target value range, and the temperature of the second cooler can be controlled within a predetermined second target value range. . Therefore, according to the present invention, it is possible to provide a refrigeration cycle apparatus that ensures the reliability of the refrigerant compressor and the inverter and the efficient operation of the refrigeration cycle apparatus.

1 is a schematic refrigerant circuit diagram illustrating an example of a refrigeration cycle apparatus 1 according to Embodiment 1 of the present invention. FIG. 2 is a schematic internal circuit diagram of an inverter 6 in the refrigeration cycle apparatus 1 according to Embodiment 1 of the present invention. It is a flowchart which shows an example of the control processing in the 1st control part 300 of the refrigerating-cycle apparatus 1 which concerns on Embodiment 1 of this invention. It is a flowchart which shows another example of the control processing in the 1st control part 300 of the refrigerating-cycle apparatus 1 which concerns on Embodiment 1 of this invention. It is a flowchart which shows an example of the control processing in the 2nd control part 400 of the refrigerating-cycle apparatus 1 which concerns on Embodiment 1 of this invention. It is a flowchart which shows another example of the control processing in the 2nd control part 400 of the refrigerating-cycle apparatus 1 which concerns on Embodiment 1 of this invention.

Embodiment 1 FIG.
A refrigeration cycle apparatus 1 according to Embodiment 1 of the present invention will be described. FIG. 1 is a schematic refrigerant circuit diagram illustrating an example of the refrigeration cycle apparatus 1 according to the first embodiment. In the following drawings including FIG. 1, the dimensional relationship and shape of each component may be different from the actual one. Moreover, in the following drawings, the same code | symbol is attached | subjected to the same or similar member or part, or the code | symbol is abbreviate | omitted.

  In the refrigeration cycle apparatus 1 according to the first embodiment, an open-type refrigerant compressor 2, a condenser 3, a first decompression device 4, and a first cooler 5 are connected via a refrigerant pipe. A refrigeration cycle that circulates refrigerant inside is provided.

  The open-type refrigerant compressor 2 includes a compression mechanism unit 22 housed in the first housing 21 and an electric motor 24 housed in the second housing 23. This is a variable frequency fluid machine in which the body 21 and the second housing 23 are configured as separate bodies. In the open type refrigerant compressor 2, the driving force generated by the rotation of the electric motor 24 is transmitted to the compression mechanism unit 22 by a power transmission mechanism 25 such as a rotating shaft, a shaft joint, a gear, a spline joint, and a belt drive. That is, in the open-type refrigerant compressor 2, the compression mechanism portion 22 is driven by the driving force generated by the rotation of the electric motor 24 transmitted by the power transmission mechanism 25, and the sucked low-pressure refrigerant is compressed and discharged as high-pressure refrigerant. . The electric motor 24 is configured as a DC brushless motor, for example.

  The condenser 3 performs heat exchange between the high-pressure refrigerant discharged from the refrigerant compressor 2 and the outside air (for example, outdoor air when the refrigeration cycle apparatus 1 is a refrigeration machine). It is a heat exchanger that releases heat. The condenser 3 can release heat to the outside air sent by an outdoor fan (not shown), for example. The condenser 3 can be configured as, for example, a cross fin type fin-and-tube heat exchanger composed of a heat transfer tube and a plurality of fins.

  The first decompression device 4 expands and decompresses the high-pressure liquid refrigerant that has flowed out of the condenser 3. As the first pressure reducing device 4, for example, an electronic expansion valve whose opening degree can be adjusted in multiple stages or continuously, such as a linear electronic expansion valve, is used.

  The first cooler 5 performs heat exchange between the refrigerant decompressed by the first decompression device 4 and air (for example, indoor air when the refrigeration cycle apparatus 1 is a refrigerator). It is a heat exchanger that cools air. The 1st cooler 5 can discharge | release heat with respect to the open air sent, for example by an indoor fan (not shown). The 1st cooler 5 can be comprised as a cross fin type fin and tube type heat exchanger comprised by the heat exchanger tube and the several fin, for example.

  Next, the inverter 6 in the refrigeration cycle apparatus 1 of the first embodiment will be described with reference to FIG. 1 and FIG. FIG. 2 is a schematic internal circuit diagram of the inverter 6 in the refrigeration cycle apparatus 1 of the first embodiment.

  As shown in FIG. 1, the refrigeration cycle apparatus 1 of the first embodiment includes an inverter 6 that supplies AC power to the electric motor 24 of the refrigerant compressor 2. As shown in FIG. 2, in the inverter 6, a rectifier circuit 61, a smoothing capacitor 63, and an inverter circuit 64 are connected in parallel, and a direct current is connected between the anode side of the rectifier circuit 61 and the anode side of the smoothing capacitor 63. A reactor 62 is connected. In the inverter 6, a resistor 65 and a contactor 66 are connected in parallel, and are arranged between the anode side of the rectifier circuit 61 and the DC reactor 62.

  The rectifier circuit 61 is, for example, a circuit that constitutes a three-phase full-wave rectifier configured by connecting six rectifier diodes 61a in a bridge connection. The AC power supply 70 that supplies an AC voltage to the rectifier circuit 61 is, for example, a commercial three-phase AC power supply of AC200V or AC400V.

  The DC reactor 62 removes a high-frequency AC component from the output voltage rectified by the rectifier circuit 61.

  The smoothing capacitor 63 smoothes the output voltage rectified by the rectifier circuit 61 and charges the output power from the rectifier circuit 61.

  The inverter circuit 64 converts the voltage (DC bus voltage) smoothed by the smoothing capacitor 63 into, for example, three-phase AC power and supplies it to the motor 24. The inverter circuit 64 includes, for example, six inverter switching elements 64a connected in a three-phase bridge. Further, at both ends of each inverter switching element 64a, a reverse current prevention element 64b for inverter for protecting the inverter switching element 64a from the motor current flowing in the reverse direction is circulated in parallel. It is connected. For the inverter backflow prevention element 64b, for example, a flywheel diode such as a rectifier diode or a Schottky barrier diode is used.

  The resistor 65 and the contactor 66 prevent the inverter 6 from being damaged due to generation of a large inrush current immediately after the start of power supply from the AC power supply 70.

  Note that the inverter 6 may be housed in the second casing 23 and the electric motor 24 may be integrated.

  Next, a cooling mechanism for cooling the inverter 6 with the refrigerant will be described with reference to FIGS. 1 and 2.

  As shown in FIG. 1, the refrigeration cycle apparatus 1 according to the first embodiment includes a bypass refrigerant pipe 7, a second decompression device 8, and a second cooler 9.

  The bypass refrigerant pipe 7 branches from the refrigerant pipe between the condenser 3 and the first pressure reducing device 4 and is connected to the refrigerant pipe between the first cooler 5 and the refrigerant compressor 2. It is.

  The second decompression device 8 is disposed in the bypass refrigerant pipe 7 and expands and decompresses the high-pressure liquid refrigerant that flows out of the condenser 3 and flows through the bypass refrigerant pipe 7. As the second pressure reducing device 8, for example, an electronic expansion valve whose opening degree can be adjusted in multiple stages or continuously, such as a linear electronic expansion valve, is used. The second decompression device 8 may have the same configuration as the first decompression device 4, or may have a different configuration.

  As shown schematically in FIGS. 1 and 2, the second cooler 9 is disposed in the bypass refrigerant pipe 7 on the outlet side of the second decompression device 8 so that the inverter 6 can be cooled. The second cooler 9 is a heat exchanger that performs heat exchange between the refrigerant decompressed by the second decompression device 8 and the heat released from the inverter 6 and cools the inverter 6 with the refrigerant. The 2nd cooler 9 can be constituted as a cross fin type fin and tube type heat exchanger constituted by a heat exchanger tube and a plurality of fins, for example. The 2nd cooler 9 is arrange | positioned in the arbitrary positions which can discharge | release the heat | fever from the inverter 6 efficiently. For example, when the inverter 6 is housed in contact with a housing (not shown), the second cooler 9 can be disposed in the portion of the housing in contact with the inverter 6. The second cooler 9 may have the same configuration as the first cooler 5 or may have a different configuration.

  Next, the sensor arrange | positioned at the refrigerating-cycle apparatus 1 which concerns on this Embodiment 1 is demonstrated.

  The refrigeration cycle apparatus 1 according to Embodiment 1 includes a first temperature sensor 100, a pressure sensor 150, and a second temperature sensor 200.

  The first temperature sensor 100 is disposed in a refrigerant pipe positioned between the connection position of the bypass refrigerant pipe 7 between the first cooler 5 and the refrigerant compressor 2 and the suction port of the refrigerant compressor 2. The suction temperature sensor detects the temperature of the refrigerant sucked into the refrigerant compressor 2 through the refrigerant pipe. Similar to the first temperature sensor 100, the pressure sensor 150 is provided between the connection position of the bypass refrigerant pipe 7 between the first cooler 5 and the refrigerant compressor 2 and the suction port of the refrigerant compressor 2. This is a suction pressure sensor that is arranged in the refrigerant pipe positioned and detects the suction pressure of the refrigerant to the refrigerant compressor 2. The second temperature sensor 200 is a cooling temperature sensor that detects the temperature of the refrigerant flowing in the second cooler 9 (hereinafter referred to as “cooling temperature”) via the second cooler 9.

  As a material of the first temperature sensor 100 and the second temperature sensor 200, a semiconductor (for example, a thermistor) or a metal (for example, a resistance temperature detector) is used. Note that the first temperature sensor 100 and the second temperature sensor 200 may be made of the same material or different materials. Further, as the pressure sensor 150, a crystal piezoelectric pressure sensor, a semiconductor sensor, a pressure transducer, or the like is used.

  Next, a control device for controlling the refrigeration cycle apparatus 1 according to Embodiment 1 will be described.

  The refrigeration cycle apparatus 1 according to the first embodiment includes a first control unit 300 that adjusts the opening degree of the first decompression device 4, and a second control unit that controls the opening degree of the second decompression device 8. 400.

  In addition, the refrigeration cycle apparatus 1 includes a calculation unit 350 that calculates the degree of superheat of the refrigeration cycle from the intake temperature detected by the first temperature sensor 100 and the intake pressure detected by the pressure sensor 150.

  The first control unit 300, the calculation unit 350, and the second control unit 400 include a microcomputer that includes a CPU, a memory (eg, ROM, RAM, etc.), an I / O port, and the like. The first control unit 300 and the second control unit 400 may be configured to perform data communication with each other, or may be configured as an integrated control device.

  The first control unit 300 controls the degree of superheat of the refrigeration cycle within a constant (first target value) range, for example, 5 to 10 ° C., by adjusting the opening degree of the first decompression device 4. The first control unit 300 constitutes a feedback control system that adjusts the opening of the first decompression device 4 based on the degree of superheat of the refrigeration cycle calculated by the calculation unit 350. In the calculation unit 350, the degree of superheat of the refrigeration cycle is calculated by converting the evaporation temperature (saturation temperature) from the suction pressure detected by the pressure sensor 150 and subtracting the evaporation temperature from the suction temperature detected by the first temperature sensor 100. Calculated. The calculation unit 350 may be configured separately from the first control unit 300 or may be configured inside the first control unit 300.

  The second control unit 400 adjusts the opening degree of the second decompression device 8 so that the cooling temperature of the second cooler 9 is in a constant (second target value) range, for example, −35 to −25 ° C. It is something to control. The first control unit 300 constitutes a feedback control system that adjusts the opening of the first decompression device 4 based on the degree of superheat of the refrigeration cycle calculated by the calculation unit 350.

  Next, the operation of the refrigeration cycle apparatus 1 according to the first embodiment will be described together with the operation of the inverter 6.

  The high-temperature and high-pressure gas refrigerant discharged from the refrigerant compressor 2 flows into the condenser 3. The high-temperature and high-pressure gas refrigerant that has flowed into the condenser 3 is heat-exchanged by releasing heat to a low-temperature medium such as outdoor air, and becomes a liquid refrigerant. The liquid refrigerant heat-exchanged in the condenser 3 flows into the first decompression device 4 and is expanded and decompressed to become a low-temperature and low-pressure two-phase refrigerant. The low-temperature and low-pressure gas-liquid two-phase refrigerant that has flowed out of the first decompression device 4 flows into the first cooler 5. The gas-liquid two-phase refrigerant that has flowed into the first cooler 5 cools (endothermics) indoor air and the like, evaporates, and becomes a two-phase refrigerant having a high degree of dryness or a low-temperature and low-pressure gas refrigerant.

  On the other hand, the AC voltage supplied to the inverter 6 by the AC power source 70 is rectified by the rectifier circuit 61 and output to the DC reactor 62 and the smoothing capacitor 63. The output voltage from the rectifier circuit 61 is removed from the high-frequency AC component by the DC reactor 62, smoothed by the smoothing capacitor 63 and charged. The output voltage from the smoothing capacitor 63 is converted into an AC voltage having an arbitrary frequency by the inverter circuit 64, and the rotational speed of the electric motor 24 is controlled according to the frequency of the converted AC voltage. Note that the ripple current generated when the AC current is converted is absorbed by the smoothing capacitor 63.

  Here, the electrical loss generated in the rectifier circuit 61, the smoothing capacitor 63, the inverter circuit 64, and the like when the inverter circuit 64 performs frequency conversion becomes heat and is released to the outside. Further, as the output power from the inverter 6 increases, the electrical loss in the inverter 6 increases and the amount of heat released to the outside also increases.

  The liquid refrigerant that has flowed through the bypass refrigerant pipe 7 branched from the refrigerant pipe between the condenser 3 and the first decompressor 4 and exchanged heat in the condenser 3 flows into the second decompressor 8 and expands. And it is decompressed to become a low-temperature and low-pressure two-phase refrigerant. The low-temperature and low-pressure gas-liquid two-phase refrigerant that has flowed out of the second decompression device 8 flows into the second cooler 9. The gas-liquid two-phase refrigerant flowing into the second cooler 9 cools (absorbs heat) the inverter 6 and evaporates to become a two-phase refrigerant having a high dryness or a low-temperature and low-pressure gas refrigerant. The highly dry two-phase refrigerant or the low-temperature and low-pressure gas refrigerant that has flowed out of the second cooler 9 merges with the gas refrigerant that has flowed out of the first cooler 5 and is sucked into the refrigerant compressor 2. The refrigerant sucked into the refrigerant compressor 2 is compressed to become a high-temperature and high-pressure gas refrigerant, and is discharged from the refrigerant compressor 2. In the refrigeration cycle apparatus 1, the above cycle is repeated.

  In the inverter 6, the contactor 66 is opened when the power supply from the AC power supply 70 is stopped, and after the start of the power supply from the AC power supply 70, the inrush current is generated for a certain period. Is controlled so that a current flows through the resistor 65. Further, the contactor 66 short-circuits both ends of the resistor 65 by connecting the contactor 66 after the current flowing through the inverter 6 is stabilized (that is, after the inrush current stops flowing). It is controlled to reduce.

  That is, after the start of power supply from the AC power supply 70, the inverter 6 is controlled so that the current flowing through the entire inverter 6 becomes small during a certain period in which the inrush current is generated. In addition, after the current flowing through the inverter 6 is stabilized, the inverter 6 is controlled so that the current flowing through the entire inverter 6 becomes large.

  In the inverter 6, since the resistance values of the smoothing capacitor 63 and the inverter circuit 64 are small, a large inrush current may be generated in the inverter 6 when the power supply from the AC power supply 70 is started, and the inverter 6 may be damaged. However, providing the resistor 65 and the contactor 66 in the inverter 6 enables stable and efficient power supply to the electric motor 24.

  Next, examples of control processing in the first control unit 300 of the refrigeration cycle apparatus 1 according to Embodiment 1 will be described in Examples 1 and 2 below.

The first control unit 300 controls the degree of superheat of the refrigeration cycle within the first target value range by adjusting the opening of the first decompression device 4. In Examples 1 and 2, the superheat degree in the refrigeration cycle is SH, the lower limit value of the target value (first target value) of the superheat degree SH is SH _lower , the upper limit value is SH _upper , and the current value of the superheat degree SH is SH _{now be} assumed. Further, the opening of the first decompression device 4 is D1, the current value of the opening D1 is D1 _now , the lower limit is D1 _lower , and the upper limit is D1 _upper . The lower limit value SH _lower and the upper limit value SH _{upper of} the superheat degree SH, and the data of the D1 _lower and the upper limit value D1 _upper of the opening degree D1 are stored so that the first control unit 300 can refer to them. For example, these data may be stored in a storage area (not shown) of the first control unit 300, or may be stored in a storage unit provided separately from the first control unit 300. Good.

Example 1
FIG. 3 is a flowchart illustrating an example of a control process in the first control unit 300 of the refrigeration cycle apparatus 1 according to the first embodiment. The control process of FIG. 3 may be performed all the time, or may be performed at any time when a change in the superheat degree SH is detected, for example.

In step S11, the first control unit 300 determines whether or not the current value SH _now of the superheat degree SH calculated by the calculation unit 350 is equal to or higher than the _upper limit value SH _upper (for example, 10 ° C.) of the superheat degree SH. To do.

When the current value SH _now of the superheat degree SH is equal to or higher than the upper limit value SH _upper of the superheat degree SH, in step S12, the first control unit 300 determines the opening degree D1 of the first pressure reducing device 4 from the current value D1 _now . And the control process is terminated.

If the current value SH _now of the superheat degree SH is less than the upper limit value SH _upper of the superheat degree SH, in step S13, the first controller 300 determines that the current value SH _now of the superheat degree SH is the lower limit value SH of the superheat degree SH. It is determined whether the temperature is _lower (for example, 5 ° C.) or less. When the current value SH _now of the superheat degree SH exceeds the _lower limit value SH _lower of the superheat degree SH, the control process ends, and the opening degree D1 is maintained at the current value D1 _now .

When the current value SH _now of the superheat degree SH is equal to or _lower than the lower limit value SH _lower of the superheat degree SH, in step S14, the first controller 300 determines the opening degree D1 of the first pressure reducing device 4 from the current value D1 _now . And the control process is terminated.

(Example 2)
FIG. 4 is a flowchart showing another example of the control process in the first control unit 300 of the refrigeration cycle apparatus 1 according to the first embodiment. The control process of FIG. 4 may be performed all the time, or may be performed at any time when a change in the superheat degree SH is detected, for example.

In step S21, as in step S11 of the first embodiment, the first control unit 300 determines whether or not the current value SH _now of the superheat degree SH is equal to or higher than the upper limit value SH _upper of the superheat degree SH.

When the current value SH _now of the superheat degree SH is equal to or higher than the upper limit value SH _upper of the superheat degree SH, in step S22, the first control unit 300 sets the current value D1 _now of the opening degree D1 of the first pressure reducing device 4. The lower limit value D1 _lower is set, and the control process is terminated.

If the current value SH _now of the superheat degree SH is less than the upper limit value SH _upper of the superheat degree SH, in step S23, the first controller 300 determines that the current value SH _now of the superheat degree SH is the lower limit value SH of the superheat degree SH. It is determined whether it is _lower or _lower . If the current value _{SH n ow} superheat SH is higher than the lower limit value _{SH lower} superheat SH, the control process is terminated.

When the current value SH _now of the superheat degree SH is equal to or _lower than the lower limit value SH _lower of the superheat degree SH, in step S24, the first control unit 300 sets the current value D1 _now of the opening degree D1 of the first decompression device 4. The upper limit value D1 _upper is set and the control process is terminated.

  The first control unit 300 may be configured to perform only one of the control processes of the first embodiment and the second embodiment, or may be configured to perform both control processes.

  Next, examples of control processing in the second control unit 400 of the refrigeration cycle apparatus 1 according to Embodiment 1 will be described in Examples 3 and 4 below.

The second control unit 400 controls the cooling temperature of the second cooler 9 within the range of the second target value by adjusting the opening of the second decompression device 8. In Examples 3 and 4, the cooling temperature of the second cooler 9 is T, the lower limit value of the target value (second target value) range of the cooling temperature T is T _lower , the upper limit value is T _upper , and the cooling temperature T _{Let Tnow be} the current value of. Further, the opening degree of the second pressure reducing device 8 D2, the current value of the opening degree D2 _{D2 now,} the lower limit value _{D2 lower,} the upper limit value and _{D2 u pper.} Data of the _lower limit value T _lower and the upper limit value T _{upper of} the cooling temperature T, and the D2 _lower and upper limit value D2 _upper of the opening degree D2 are stored so that the second control unit 400 can refer to them. For example, these data may be stored in a storage area (not shown) provided in the second control unit 400 or stored in a storage unit provided separately from the second control unit 400. You may make it do.

(Example 3)
FIG. 5 is a flowchart illustrating an example of a control process in the second control unit 400 of the refrigeration cycle apparatus 1 according to the first embodiment. The control process of FIG. 5 may be performed all the time, or may be performed at any time when a change in the cooling temperature T is detected, for example.

In step S31, the second control unit 400 determines whether the current value _Tnow of the cooling temperature T detected by the second temperature sensor 200 is equal to or higher than the _upper limit value T _upper (for example, −25 ° C.) of the cooling temperature T. Determine whether or not.

  Current value T of cooling temperature T_nowIs the upper limit T of the cooling temperature T_upperWhen it is above, in Step S32, the 2nd control part 400 sets opening degree D2 of the 2nd decompression device 8 as present value D2. _nowAnd the control process is terminated.

If the current value _{T now} cooling temperature T is less than the upper limit value _{T upper} cooling temperature T, in step S33, the second controller 400, the current value _{T now} cooling temperature T lower limit value T of the cooling temperature T It is determined whether the temperature is _lower (for example, −35 ° C.) or less. If the current value _{T now} cooling temperature T is higher than the lower limit value _{T lower} cooling temperature T, the control process ends and opening D2 is maintained at a current value _{D2 now.}

  Current value T of cooling temperature T_nowIs the lower limit T of the cooling temperature T_lowerIn the case of the following, in step S34, the second control unit 400 sets the opening degree D2 of the second decompression device 8 to the current value D2. _nowThe control process is terminated after adjusting so as to be smaller.

Example 4
FIG. 6 is a flowchart illustrating another example of the control process in the second control unit 400 of the refrigeration cycle apparatus 1 according to the first embodiment. The control process of FIG. 6 may be performed all the time, or may be performed at any time when a change in the cooling temperature T is detected, for example.

In step S41, similarly to step S31 in Embodiment 3, the second control unit 400, the current value _{T now} is equal to or more than the upper limit value _{T upper} cooling temperature T of the cooling temperature T.

  Current value T of cooling temperature T_nowIs the upper limit T of the cooling temperature T_upperWhen it is above, in step S42, the 2nd control part 400 is the present value D2 of the opening degree D2 of the 2nd decompression device 8. _nowIs the lower limit D2_lowerTo complete the control process.

If the current value _{T now} cooling temperature T is less than the upper limit value _{T upper} cooling temperature T, in step S43, the second controller 400, the current value _{T now} cooling temperature T lower limit value T of the cooling temperature T It is determined whether it is _lower or _lower . When the current value _Tnow of the cooling temperature T exceeds the _lower limit value _Tlower of the cooling temperature T, the control process is terminated.

  Current value T of cooling temperature T_nowIs the lower limit T of the cooling temperature T_lowerWhen it is below, in step S44, the 2nd control part 400 is the present value D2 of the opening degree D2 of the 2nd decompression device 8. _nowIs the upper limit D2_upperTo complete the control process.

  The second control unit 400 may be configured to perform only one of the control processes of the third embodiment and the fourth embodiment, or may be configured to perform both control processes.

  The effects of the present invention according to the first embodiment will be described below.

  As described above, the refrigeration cycle apparatus 1 according to Embodiment 1 includes the compression mechanism unit 22 housed in the first housing 21 and the electric motor 24 housed in the second housing 23. An open-type refrigerant compressor 2, a condenser 3, a first decompression device 4, a first casing 21 and a second casing 23, which are configured separately. A refrigerating cycle connected to the cooler 5 via a refrigerant pipe and circulating the refrigerant therein, an inverter 6 that supplies AC power to the electric motor 24, and a refrigerant between the condenser 3 and the first decompressor 4 A bypass refrigerant pipe 7 branched from the pipe and connected to a refrigerant pipe between the first cooler 5 and the refrigerant compressor 2, a second decompression device 8 disposed in the bypass refrigerant pipe 7, and a second The second cooling unit 7 is disposed in the bypass refrigerant pipe 7 on the outlet side of the decompression device 8 and cools the inverter 6. A first control unit 300 that adjusts the opening degree of the first decompression device 4 and a second control unit 400 that controls the opening degree of the second decompression device 8. The unit 300 controls the degree of superheating of the refrigeration cycle to the range of the first target value by adjusting the opening degree of the first pressure reducing device 4, and the second control unit 400 opens the second pressure reducing device 8. By adjusting the degree, the cooling temperature of the second cooler 9 is controlled within the range of the second target value.

  2. Description of the Related Art Conventionally, a refrigeration cycle apparatus that performs operation frequency control of a refrigerant compressor with an inverter for the purpose of improving partial load efficiency is known. In such a refrigeration cycle apparatus, when the output power of the inverter increases, the heat generation from the inverter increases in proportion to the increase in the inverter output power. Therefore, it is necessary to diffuse and cool the heat generation from the inverter.

  As a conventional inverter cooling method, a method of attaching a heat sink or the like to a rectifier circuit or the like to diffuse the heat generated from the inverter, blowing air around the inverter to the heat sink or the like, and cooling the heat sink or the like has been adopted. . However, in the method of cooling the inverter by blowing air, a large blower fan and a large cooling air passage are required to secure the cooling air volume. In addition, as the output power of the inverter in the refrigeration cycle apparatus increases, the required amount of cooling air also increases, which increases the design restrictions of the refrigeration cycle apparatus.

  As a method of eliminating the design restrictions of the refrigeration cycle apparatus, there is a method of cooling the inverter with a refrigerant. In the method of cooling the inverter with the refrigerant, a fan and a cooling air passage are not necessary, and thus the design restrictions of the refrigeration cycle apparatus can be eliminated. As a method of cooling an inverter with a refrigerant, a cooling method by controlling a decompression device and a cooling method without providing a dedicated cooling circuit for inverter cooling are known.

  However, in the conventional method in which the inverter is cooled by the refrigerant, the refrigerant that has cooled the inverter joins the refrigerant flowing through the refrigeration cycle and is sucked into the refrigerant compressor. It depends on the temperature of the cooled refrigerant. Therefore, in the refrigeration cycle apparatus that employs the conventional method of cooling the inverter with the refrigerant, the refrigerant sucked into the refrigerant compressor becomes a liquid refrigerant or a gas refrigerant with a high degree of superheat, and a stable operation state of the refrigerant compressor cannot be secured. There was a problem that there was a case.

  There is also known a refrigeration cycle apparatus that cools an inverter with refrigerant flowing through an intermediate injection mechanism or the like, that is, does not cool an inverter with refrigerant sucked by a refrigerant compressor. However, in such a refrigeration cycle apparatus, since a control method for cooling the inverter is not shown, the inverter may be overheated due to insufficient refrigerant flow rate, or the inverter may be condensed due to excessive refrigerant flow rate. Therefore, such a refrigeration cycle apparatus has a problem that the inverter may be damaged.

  On the other hand, according to the first embodiment, the first controller 300 can adjust the flow rate of the refrigerant sucked by the refrigerant compressor 2 by adjusting the opening degree of the first decompression device 4, The degree of superheat of the refrigeration cycle can be controlled within a certain range (first target value range). Therefore, by controlling the degree of superheat of the refrigeration cycle to the range of the first target value, the compression mechanism 22 of the refrigerant compressor 2 can inhale liquid refrigerant or can inhale gas refrigerant with high degree of superheat. Can be avoided.

  Further, according to the first embodiment, the second control unit 400 adjusts the opening degree of the second decompression device 8, thereby adjusting the flow rate of the refrigerant flowing through the second cooler 9 that cools the inverter. The cooling temperature of the second cooler 9 can be controlled within a certain range (second target value range). Therefore, by controlling the cooling temperature of the second cooler 9 within the range of the second target value, the overheating of the inverter 6 due to the insufficient flow rate of the refrigerant flowing through the second cooler 9 can also be prevented. Condensation of the inverter 6 due to an excessive flow rate of the refrigerant flowing through can also be avoided.

  Therefore, according to the first embodiment, the reliability of the refrigerant compressor 2 can be ensured, the refrigeration cycle apparatus 1 can be efficiently operated, the damage to the inverter 6 can be avoided, and the reliability can be ensured. it can. Further, the energy consumption can be reduced by the efficient operation of the refrigeration cycle apparatus 1, and the durability of the refrigerant compressor 2 and the inverter 6 can be improved.

  Further, the smoothing capacitor 63 provided in the inverter 6 has a characteristic that the ripple current that can be absorbed increases as the temperature decreases. Therefore, in the first embodiment, the smoothing capacitor 63 having a small capacity can be selected by controlling the temperature range of the cooling temperature of the second cooler 9 to a low temperature having an upper limit of −35 ° C., for example. . Therefore, there is an advantage that the manufacturing cost of the inverter 6 can be reduced and the environmental load can be reduced.

  In addition, the refrigeration cycle apparatus 1 according to the first embodiment has a low global warming potential and a configuration that takes into account the use of a flammable refrigerant, so that the refrigeration cycle apparatus 1 can be used safely. It also has the advantage of.

  In recent years, in response to the recent global warming problem, in the refrigerant used in the refrigeration cycle apparatus, the movement of putting a refrigerant having a low global warming coefficient (hereinafter referred to as “low GWP refrigerant”) into practical use in Europe. It is becoming more active.

  On the other hand, CF for low GWP refrigerant₃-CF = CH₂(HFO1234yf) and CH₂F ₂There is a refrigerant having combustibility such as (R32). In the case of using a combustible low GWP refrigerant, in a refrigeration cycle apparatus such as an air conditioner or a refrigerator, an electric device such as an electric motor cannot be disposed in the refrigerant atmosphere due to safety restrictions.

  On the other hand, the refrigeration cycle apparatus 1 according to the first embodiment includes an open-type refrigerant compressor 2. That is, in the refrigerant compressor 2 of the first embodiment, the first housing 21 that houses the compression mechanism 22 and the second housing 23 that houses the electric motor 24 are configured as separate bodies. Therefore, according to the first embodiment, the refrigeration cycle apparatus 1 can be used safely even when a combustible low GWP refrigerant is used.

  In the refrigeration cycle apparatus 1 according to the first embodiment, the adjustment of the opening degree of the first decompression apparatus 4 is performed when the degree of superheat of the refrigeration cycle, which is a controlled variable, is equal to or higher than the upper limit value of the first target value When the degree of superheat of the refrigeration cycle, which is the control amount, is less than or equal to the lower limit value of the first target value, the first opening amount, which is the operation amount, is increased. It is configured to be performed by lowering the opening of the decompression device 4. According to this configuration, the opening degree of the first decompression device 4 can be adjusted based on the degree of superheat of the refrigeration cycle calculated from the suction temperature detected by the first temperature sensor 100 and the suction pressure detected by the pressure sensor 150. The flow rate of the refrigerant passing through the first cooler 5 is increased or decreased. The superheat degree of the refrigeration cycle is controlled to be within the range of the first target value, for example, 5 to 10 ° C., by increasing or decreasing the flow rate of the refrigerant passing through the first cooler 5. Therefore, according to this configuration, it is possible to avoid that the degree of superheat of the refrigerant becomes excessively small, and the liquid refrigerant is sucked into the compression mechanism portion 22 of the refrigerant compressor 2 and the liquid compressor operation is performed in the refrigerant compressor 2. Further, according to this configuration, it is possible to avoid that the superheat degree of the refrigerant becomes excessive, and that the gas refrigerant having a high superheat degree is sucked into the compression mechanism portion 22 of the refrigerant compressor 2 and the refrigerant compressor 2 is overheated. . Therefore, according to this configuration, the refrigerant compressor 2 can be prevented from being damaged by controlling the degree of superheat of the refrigerant sucked into the compression mechanism unit 22 within the range of the first target value. In addition, since the heat exchange in the first cooler 5 is sufficiently performed, the refrigeration cycle apparatus 1 can be efficiently operated.

  Further, in the refrigeration cycle apparatus 1 according to the first embodiment, when the superheat degree of the refrigeration cycle that is the control amount is equal to or higher than the upper limit value of the first target value, the first decompression apparatus 4 that is the manipulated variable. When the opening degree is set as the lower limit value of the opening degree of the first decompression device 4 and the degree of superheat of the refrigeration cycle, which is the control amount, is less than or equal to the lower limit value of the first target value, the first operation amount The opening degree of the decompression device 4 is set as the upper limit value of the opening degree of the first decompression device 4. According to this configuration, since the lower limit value or the upper limit value of the opening degree of the first decompression device 4 is set depending on the degree of superheat of the refrigeration cycle, the flow rate of the refrigerant passing through the first cooler 5 increases excessively. And excessive reduction can be suppressed (prohibited). Therefore, according to this configuration, it is possible to avoid that the degree of superheat of the refrigerant becomes excessively small, and the liquid refrigerant is sucked into the compression mechanism portion 22 of the refrigerant compressor 2 and the liquid compressor operation is performed in the refrigerant compressor 2. Further, according to this configuration, it is possible to avoid that the superheat degree of the refrigerant becomes excessive, and that the gas refrigerant having a high superheat degree is sucked into the compression mechanism portion 22 of the refrigerant compressor 2 and the refrigerant compressor 2 is overheated. . Therefore, according to this configuration, by setting the lower limit value or the upper limit value of the opening degree of the first decompression device 4, it is possible to prevent the compression mechanism unit 22 from being damaged, and to improve the efficiency of the refrigeration cycle apparatus 1. Can be operated.

  Further, in the refrigeration cycle apparatus 1 according to the first embodiment, the opening degree of the second decompression device 8 is adjusted when the cooling temperature, which is the controlled variable, becomes equal to or higher than the upper limit value of the second target value. The opening degree of the second decompression device 8 as the operation amount is increased when the opening degree of the second decompression device 8 as the amount is increased and the cooling temperature as the control amount becomes equal to or lower than the lower limit value of the second target value. Is done by lowering. According to this configuration, the opening degree of the second decompression device 8 is adjusted by the cooling temperature of the second cooler 9 detected by the second temperature sensor 200, and passes through the second cooler 9. The flow rate of the refrigerant is increased or decreased. By controlling the flow rate of the refrigerant passing through the second cooler 9, the cooling temperature of the second cooler 9 is controlled to be within the range of the second target value, for example, −35 to −25 ° C. Therefore, according to this structure, it can avoid that the flow volume of the refrigerant | coolant which flows through the 2nd cooler 9 runs short, and the inverter 6 overheats. Moreover, according to this structure, it can avoid that the flow volume of the refrigerant | coolant which flows through the 2nd cooler 9 becomes excessive, and the inverter 6 dew condensation. Therefore, according to this configuration, by controlling the cooling temperature of the second cooler 9 within the range of the second target value, damage to the internal circuit of the inverter 6 due to overheating or condensation of the inverter 6 can be avoided. can do.

  Further, in the refrigeration cycle apparatus 1 according to the first embodiment, the opening degree of the second decompression device 8 is adjusted when the cooling temperature, which is the controlled variable, becomes equal to or higher than the upper limit value of the second target value. When the opening degree of the second decompression device 8 that is the amount is set as the lower limit value of the opening degree of the second decompression device 8, and the cooling temperature that is the control amount becomes equal to or less than the lower limit value of the second target value The opening amount of the second decompression device 8 that is the manipulated variable is set as the upper limit value of the opening degree of the second decompression device 8. According to this configuration, since the lower limit value or the upper limit value of the opening degree of the second decompression device 8 is set by the cooling temperature of the second cooler 9, the flow rate of the refrigerant passing through the second cooler 9 Can be suppressed (prohibited) from excessively increasing or decreasing excessively. Therefore, according to this structure, it can avoid that the flow volume of the refrigerant | coolant which flows through the 2nd cooler 9 runs short, and the inverter 6 overheats. Moreover, according to this structure, it can avoid that the flow volume of the refrigerant | coolant which flows through the 2nd cooler 9 becomes excessive, and the inverter 6 dew condensation. Therefore, according to this configuration, by setting the lower limit value or the upper limit value of the opening degree of the second decompression device 8, damage to the internal circuit of the inverter 6 due to overheating or condensation of the inverter 6 can be avoided. Can do.

Embodiment 2. FIG.
In the second embodiment of the present invention, a modification of the compression mechanism portion 22 of the refrigerant compressor 2 in FIG. 1 in the above-described first embodiment will be described.

  In the refrigeration cycle apparatus 1 according to the second embodiment, the compression method of the compression mechanism unit 22 is configured to be a screw type. Further, in the refrigeration cycle apparatus 1 of the second embodiment, the compression method of the compression mechanism unit 22 is configured to be a turbo type. By setting the compression method of the compression mechanism unit 22 to the screw type or turbo type compression method, for example, the vibration in the refrigerant compressor 2 can be suppressed as compared with the case where the compression mechanism unit 22 of the reciprocating type compression method is used. Therefore, according to this configuration, the possibility of damage to the inverter 6 due to vibration of the refrigerant compressor 2 can be reduced.

  In the refrigeration cycle apparatus 1 of the second embodiment, the compression method of the compression mechanism unit 22 is configured to be a two-stage compression type. In the two-stage compression type compression mechanism section 22, the eccentric portion of the crankshaft is disposed 180 degrees opposite. In the second embodiment, the compression mechanism of the compression mechanism unit 22 is a two-stage compression method, so that the axial load is reduced and the reliability of the compression mechanism unit 22 can be improved. Further, since the axial load is reduced, the torque fluctuation of the compression mechanism portion 22 is reduced, and the vibration in the rotational direction is greatly reduced. Therefore, according to this configuration, the possibility of damage to the inverter 6 due to vibration of the refrigerant compressor 2 can be reduced.

Embodiment 3 FIG.
In the third embodiment of the present invention, a modification of the second casing 23 of the refrigerant compressor 2 in FIG. 1 in the above-described first embodiment will be described.

  In the refrigeration cycle apparatus 1 of the third embodiment, the inverter 6 is configured to be housed in the second casing 23 together with the electric motor 24. According to this configuration, it is not necessary to provide the inverter 6 in a separate housing, so that space saving of the refrigeration cycle apparatus 1 can be achieved.

  Further, in the refrigeration cycle apparatus 1 of the third embodiment, the second casing 23 in which the inverter 6 is accommodated is configured as a grounded conductive fully sealed container. The fully sealed container can be made of a metal material such as aluminum. In the inverter 6, electromagnetic wave noise is generated when alternating current is converted into direct current and when direct current is converted into alternating current. When electromagnetic noise occurs, electronic devices around the inverter 6 may malfunction, but according to this configuration, the inverter 6 is electrostatically shielded inside the second casing 23. Therefore, according to this configuration, radiation of electromagnetic noise from the inverter 6 to the outside of the second housing 23 can be reduced.

Embodiment 4 FIG.
In the fourth embodiment of the present invention, a modification of the first decompression device 4 and the second decompression device 8 in FIG.

  In the refrigeration cycle apparatus 1 according to the fourth embodiment, at least one of the first decompression device and the second decompression device is configured as an expander. The expander is a fluid machine that can expand (depressurize) the sucked high-pressure liquid refrigerant by an expansion mechanism, discharge it as a low-temperature and low-pressure refrigerant, and mechanically recover the expansion power obtained by the expansion mechanism. The recovered expansion power can be used as, for example, the compression power of the refrigerant in the refrigerant compressor 2. Therefore, according to this configuration, the electric input can be reduced and the coefficient of performance (COP) can be improved.

  Further, the refrigeration cycle apparatus 1 of the fourth embodiment may be configured such that power generation is performed by the expansion power recovered by the expander. According to this configuration, the main body electrical equipment of the refrigeration cycle apparatus 1 such as the refrigerant compressor 2, the inverter 6, the first control unit 300, the second control unit 400, or the like using the generated electric power, or not illustrated, Other electric devices such as blowers, pumps, and auxiliary machines can be driven. Moreover, according to this structure, a compressor (for example, refrigerant compressor 2) and an expander can be comprised as a different body. Therefore, according to this configuration, there is no need to provide a dedicated fluid machine in which the compressor and the expander are integrated to effectively use the expansion power obtained by the expansion mechanism of the expander, which is conventionally used. Therefore, the cost of the refrigeration cycle apparatus 1 can be reduced.

  In the case where the first decompressor 4 or the second decompressor 8 is configured as an expander, the refrigeration cycle apparatus 1 may be provided with a bypass circuit in which a part of the refrigerant does not flow through the expander. According to this configuration, it is possible to perform an operation in which the mass flow rates of the refrigerant of the refrigerant compressor 2 and the refrigerant of the expander are different, and even when the operating conditions of the refrigeration cycle apparatus 1 change, such as when the low pressure decreases. The coefficient can be improved.

Embodiment 5. FIG.
In the fifth embodiment of the present invention, a modified example of the refrigeration cycle apparatus 1 in the above-described first embodiment will be described.

  In the refrigeration cycle apparatus 1 of the fifth embodiment, for example, an ejector is provided to recover the suction pressure. An ejector is a device that boosts a low-pressure refrigerant. The ejector is disposed, for example, in a refrigerant pipe located between the connection position of the bypass refrigerant pipe 7 between the first cooler 5 and the refrigerant compressor 2 and the suction port of the refrigerant compressor 2, and refrigerant compression The suction pressure in the machine 2 is recovered. According to this configuration, the pressure of the two-phase refrigerant flowing through the first cooler 5 and the second cooler 9 can be reduced by the amount boosted by the ejector. Therefore, according to this configuration, since the saturation temperature of the two-phase refrigerant flowing through the first cooler 5 and the second cooler 9 can be lowered, the cooling capacity of the refrigeration cycle apparatus 1 is improved, and the coefficient of performance is improved. Can be improved.

Embodiment 6 FIG.
In the sixth embodiment of the present invention, a modified example of the refrigerant compressor 2 in the first embodiment will be described.

  In this Embodiment 6, the case where only the low GWP refrigerant | coolant which does not have slight flammability is considered. When a low GWP refrigerant having combustibility is used, the electric motor 24 and the inverter 6 cannot be accommodated in the same casing as the compression mechanism unit 22 due to safety restrictions. However, when only the low GWP refrigerant that does not have a slight flammability is used as in the sixth embodiment, the electric motor 24 and the inverter 6 can be configured integrally with the compression mechanism unit 22. In the sixth embodiment, the inverter 6 is cooled by the refrigerant sucked into the refrigerant compressor 2. Therefore, the cooling of the inverter 6 in the sixth embodiment is performed by controlling the flow rate of the refrigerant sucked into the refrigerant compressor 2. The control of the flow rate of the refrigerant sucked into the refrigerant compressor 2 is based on the degree of superheat of the refrigeration cycle calculated from the suction temperature detected by the first temperature sensor 100 and the suction pressure detected by the pressure sensor 150. Done.

Other embodiments.
The present invention is not limited to the above-described embodiment, and various modifications can be made. For example, the above-described embodiment can be used for a heat pump device such as a showcase, an air conditioner, or a refrigerator.

  Further, the above-described embodiments can be used in combination with each other.

DESCRIPTION OF SYMBOLS 1 Refrigeration cycle apparatus, 2 Refrigerant compressor, 3 Condenser, 1st decompression device, 5 1st cooler, 6 Inverter, 7 Bypass refrigerant | coolant piping, 8 2nd decompression device, 9 2nd cooler, 21 1st housing | casing, 22 Compression mechanism part, 23 2nd housing | casing, 24 Electric motor, 25 Power transmission mechanism, 61 Rectifier circuit, 61a Rectifier diode, 62 DC reactor, 63
Smoothing capacitor, 64 inverter circuit, 64a inverter switching element, 64b inverter backflow prevention element, 65 resistor, 66 contactor, 70 AC power supply, 100 first temperature sensor, 150 pressure sensor, 200 second temperature sensor, 300 1st control part, 350 calculating part, 400 2nd control part.

Claims (12)

A refrigerant compressor having a compression mechanism section and an electric motor, a condenser, a first decompression device, and a first cooler are connected via a refrigerant pipe, and a refrigeration cycle for circulating the refrigerant inside;
An inverter for supplying AC power to the electric motor;
A bypass refrigerant pipe branched from a refrigerant pipe between the condenser and the first pressure reducing device and connected to a refrigerant pipe between the first cooler and the refrigerant compressor;
A second pressure reducing device disposed in the bypass refrigerant pipe;
A second cooler disposed in the bypass refrigerant pipe on the outlet side of the second decompression device and cooling the inverter;
A first controller that adjusts the opening of the first decompressor;
A second control unit for controlling the opening of the second decompression device,
The first control unit controls the degree of superheat of the refrigeration cycle to a range of a first target value only by adjusting the opening of the first pressure reducing device. When the degree of superheat of the refrigeration cycle, which is a control amount, is equal to or higher than the upper limit value of the first target value, the opening degree is adjusted by increasing the opening degree of the first decompression device, which is an operation amount. When the degree of superheat of the refrigeration cycle, which is an amount, is less than or equal to the lower limit value of the first target value, the opening amount of the first decompression device, which is an operation amount, is reduced,
The second control unit is a refrigeration cycle apparatus that controls a cooling temperature of the second cooler within a range of a second target value by adjusting an opening degree of the second decompression device. The refrigerant compressor is
The compression mechanism is housed in the first housing;
The electric motor is housed in a second housing;
An open type refrigerant compressor in which the first casing and the second casing are configured separately;
The refrigeration cycle apparatus according to claim 1, wherein the refrigerant is a refrigerant having combustibility and a low global warming potential.   The refrigeration cycle apparatus according to claim 2, wherein the inverter is housed in the second casing together with the electric motor.   The refrigeration cycle apparatus according to claim 3, wherein the second casing is a grounded conductive fully sealed container. The adjustment of the opening of the first pressure reducing device is as follows:
When the degree of superheat of the refrigeration cycle, which is a controlled variable, is equal to or greater than the upper limit value of the first target value, the opening of the first decompressor, which is the manipulated variable, is set to the opening of the first decompressor. Set as the lower limit of
When the degree of superheat of the refrigeration cycle, which is a controlled variable, is less than or equal to the lower limit value of the first target value, the opening of the first decompressor, which is the manipulated variable, is set to the opening of the first decompressor. The refrigeration cycle apparatus according to any one of claims 1 to 4, wherein the refrigeration cycle apparatus is performed by setting as an upper limit value. Adjustment of the opening of the second decompression device is
When the cooling temperature that is a control amount becomes equal to or higher than the upper limit value of the second target value, the opening of the second pressure reducing device that is an operation amount is increased,
6. The method according to claim 1, wherein the control is performed by lowering an opening of the second pressure reducing device, which is an operation amount, when the cooling temperature, which is a control amount, is equal to or lower than a lower limit value of the second target value. The refrigeration cycle apparatus according to claim 1. Adjustment of the opening of the second decompression device is
When the cooling temperature, which is a control amount, is equal to or higher than the upper limit value of the second target value, the opening degree of the second pressure reducing device, which is an operation amount, is set to the lower limit value of the opening degree of the second pressure reducing device. Set as
When the cooling temperature, which is a control amount, is equal to or lower than the lower limit value of the second target value, the opening degree of the second decompression device, which is an operation amount, is set to the upper limit value of the opening degree of the second decompression device. The refrigeration cycle apparatus according to any one of claims 1 to 6, wherein the refrigeration cycle apparatus is performed by setting as follows.   The refrigeration cycle apparatus according to any one of claims 1 to 7, wherein a compression method of the compression mechanism unit is a screw type.   The refrigeration cycle apparatus according to any one of claims 1 to 7, wherein a compression system of the compression mechanism section is a turbo system.   The refrigeration cycle apparatus according to any one of claims 1 to 9, wherein a compression method of the compression mechanism unit is a two-stage compression type.   The refrigeration cycle apparatus according to any one of claims 1 to 10, wherein at least one of the first decompressor and the second decompressor is an expander.   The refrigeration cycle apparatus according to claim 11, wherein power generation is performed by expansion power recovered by the expander.

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