JP2007147211A - Control method for refrigerating cycle device and refrigerating cycle device using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To stabilize operation of a refrigerating cycle device equipped with an expansion mechanism capable of recovering pressure energy at the time of expansion, and especially, to improve stability at the start of its operation. <P>SOLUTION: The refrigerating cycle device is equipped with a compression mechanism 2, a heat-source-side heat exchanger 6, the expansion mechanism for recovering power, and a use-side heat exchanger 3. The method for controlling the refrigerating cycle device is characterized to control the rotating speed of the expansion mechanism 5 so as to become a first target expansion mechanism rotating speed determined from the discharge temperature of the compression mechanism 2. With the method, the rotating speed of the expansion mechanism 5 can be suitably controlled and the refrigerating cycle device can be stably operated, and especially, the stability at start of the operation of the refrigerating cycle can be improved. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a control method for a refrigeration cycle apparatus having an expansion mechanism for recovering power and a refrigeration cycle apparatus using the same.

A refrigeration cycle apparatus has been proposed in which an expansion mechanism is provided instead of a decompressor, and pressure energy at the time of expansion is recovered as power to improve COP (see, for example, Patent Document 1).
JP-A-56-112896

  In the above prior art, when the temperature of the heat source side fluid flowing into the heat source side heat exchanger or the temperature of the usage side fluid flowing into the usage side heat exchanger is high, the discharge temperature and the high pressure side pressure of the compression mechanism rise. There is a problem that the operation of the compression mechanism is frequently stopped to protect the device.

  Then, in order to solve the above-mentioned problem, the present invention aims to control the rotation speed of the expansion mechanism appropriately in the refrigeration cycle apparatus provided with the expansion mechanism and to operate the refrigeration cycle apparatus stably. It aims at improving the stability at the time of starting of a refrigerating cycle device.

In order to solve the above-described conventional problems, a control method for a refrigeration cycle apparatus according to the present invention includes a first target expansion mechanism rotational speed determined from a discharge temperature of a compression mechanism in a refrigeration cycle apparatus including an expansion mechanism that performs power recovery. Thus, the rotational speed of the expansion mechanism is controlled. According to this, since the discharge temperature does not greatly deviate from the target discharge temperature, it is not necessary to stop the operation of the compression mechanism or the like in order to protect the refrigeration cycle apparatus, and the refrigeration cycle apparatus can be operated stably. .

  In the refrigeration cycle apparatus control method of the present invention, in the refrigeration cycle apparatus provided with an expansion mechanism for recovering power, when the discharge temperature of the compression mechanism is higher than a predetermined target discharge temperature, the expansion mechanism When the rotational speed is increased and lower than the target discharge temperature, the rotational speed of the expansion mechanism is decreased. According to this, when the discharge temperature exceeds the target discharge temperature, the rotation speed of the expansion mechanism is increased and the discharge temperature is decreased, and when the discharge temperature is lower than the target discharge temperature, the rotation speed of the expansion mechanism is decreased. Since the discharge temperature does not deviate greatly from the target discharge temperature because the discharge temperature is lowered and the discharge temperature is increased, it is not necessary to stop the operation of the compression mechanism or the like in order to protect the refrigeration cycle device, and the refrigeration can be stably performed. The cycle device can be operated.

  In the refrigeration cycle apparatus control method according to the present invention, in the refrigeration cycle apparatus having an expansion mechanism for recovering power, the rotation speed of the expansion mechanism exceeds a predetermined upper limit value of the use range of the rotation speed of the expansion mechanism. In this case, the rotational speed of the compression mechanism is reduced. According to this, even when the discharge temperature is higher than the target discharge temperature and the rotation speed of the expansion mechanism is higher than the upper limit rotation speed, the rotation speed of the compression mechanism is decreased and the discharge temperature is lowered. In addition, it is not necessary to stop the operation of the compression mechanism in order to protect the expansion mechanism and the like, and the refrigeration cycle apparatus can be stably operated.

In the refrigeration cycle apparatus control method according to the present invention, in the refrigeration cycle apparatus including an expansion mechanism that performs power recovery, the rotation speed of the expansion mechanism exceeds a lower limit value of a predetermined use range of the rotation speed of the expansion mechanism. In this case, the rotational speed of the compression mechanism is increased. According to this, even when the discharge temperature is lower than the target discharge temperature and the rotation speed of the expansion mechanism is smaller than the lower limit rotation speed of use, the rotation speed of the compression mechanism is increased and the discharge temperature is increased. There is no need to stop the operation of the compression mechanism or the like to protect the expansion mechanism or the like, and the refrigeration cycle apparatus can be stably operated.

  Further, according to the control method of the refrigeration cycle apparatus of the present invention, in the refrigeration cycle apparatus having an expansion mechanism for recovering power, the rotation speed of the expansion mechanism is changed at the same time as or before the rotation speed of the compression mechanism is changed. To change. According to this, a rapid change in the high-pressure side pressure when the rotation speed of the compression mechanism changes can be prevented, and a stable start-up of the refrigeration cycle apparatus can be realized.

  The control method for the refrigeration cycle apparatus according to the present invention includes a heat source side fluid temperature flowing into the heat source side heat exchanger and a utilization side flowing into the utilization side heat exchanger in the refrigeration cycle apparatus having an expansion mechanism for performing power recovery. The rotation speed of the expansion mechanism is maintained for a predetermined time at the second target expansion mechanism rotation speed determined from at least one of the fluid temperatures. According to this, the second target expansion mechanism rotational speed is set so that the rotational speed increases as the high-pressure side pressure easily rises according to the outside air temperature and the incoming water temperature. The rise can be prevented, and a stable refrigeration cycle apparatus can be started.

  The control method for the refrigeration cycle apparatus according to the present invention includes a heat source side fluid temperature flowing into the heat source side heat exchanger and a utilization side flowing into the utilization side heat exchanger in the refrigeration cycle apparatus having an expansion mechanism for performing power recovery. The second target expansion mechanism rotation speed determined from at least one of the fluid temperatures is maintained at the rotation speed of the expansion mechanism for a predetermined time, and after the predetermined time has elapsed, the first target expansion determined from at least the discharge temperature of the compression mechanism. The rotation speed of the expansion mechanism is controlled so as to be the mechanism rotation speed. According to this, the second target expansion mechanism rotation speed is set so that the rotation speed increases as the pressure on the high pressure side increases more easily according to the outside air temperature and the incoming water temperature. When the rotation speed increases to the first target expansion mechanism rotation speed, a rapid increase in the high-pressure side pressure can be prevented, and stable start-up of the refrigeration cycle apparatus can be realized.

  The control method for the refrigeration cycle apparatus according to the present invention includes a heat source side fluid temperature flowing into the heat source side heat exchanger and a utilization side flowing into the utilization side heat exchanger in the refrigeration cycle apparatus having an expansion mechanism for performing power recovery. The second target expansion mechanism rotation speed determined from at least one of the fluid temperatures is maintained at the rotation speed of the expansion mechanism for a predetermined time, and after the predetermined time has elapsed, the heat source side fluid temperature flowing into the heat source side heat exchanger, The rotation speed of the expansion mechanism is controlled to a third target expansion mechanism rotation speed determined from at least one temperature of the use-side fluid temperature flowing into the use-side heat exchanger, and after a predetermined elapse, at least from the discharge temperature of the compression mechanism The rotation speed of the expansion mechanism is controlled so as to be the first target expansion mechanism rotation speed to be determined. According to this, it is possible to prevent a rapid change in the high-pressure side pressure when the rotation speed of the expansion mechanism increases from the second target expansion mechanism rotation speed to the first target expansion mechanism rotation speed, and to stabilize while reducing the start-up time. The refrigeration cycle apparatus can be started up.

  In the refrigeration cycle apparatus control method of the present invention, in the refrigeration cycle apparatus provided with an expansion mechanism for recovering power, if the discharge temperature of the compression mechanism approaches a predetermined target discharge temperature, the predetermined time is ended. Judgment. According to this, it is possible to shorten the time required for operation at an unnecessarily low target expansion mechanism rotation speed, and it is possible to realize stable start-up of the refrigeration cycle apparatus while shortening the start-up time.

In the refrigeration cycle apparatus according to the present invention, the refrigeration cycle apparatus including the expansion mechanism that performs power recovery, if the use side fluid temperature flowing into the use side heat exchanger approaches a predetermined target temperature, It is determined that the predetermined time has ended. According to this, it is possible to shorten the time required for operation at an unnecessarily low target expansion mechanism rotation speed, and it is possible to realize stable start-up of the refrigeration cycle apparatus while shortening the start-up time.

  In the refrigeration cycle apparatus control method according to the present invention, in the refrigeration cycle apparatus having an expansion mechanism for recovering power, the use side fluid temperature at which the discharge temperature of the compression mechanism flows into the predetermined use side heat exchanger is determined. If the predetermined temperature difference is higher than the target temperature by a certain temperature, it is determined that the predetermined time has ended. According to this, it is possible to shorten the time required for operation at an unnecessarily low target expansion mechanism rotation speed, and it is possible to realize stable start-up of the refrigeration cycle apparatus while shortening the start-up time.

  Moreover, the refrigerating cycle apparatus of this invention is a refrigerating cycle apparatus which performs the said control method. According to this, it is possible to realize a refrigeration cycle apparatus capable of performing stable start-up and operation.

  In the refrigeration cycle apparatus of the present invention, the refrigerant is carbon dioxide. In this case, the high pressure side pressure is likely to increase, and the effect of realizing a stable operation of the refrigeration cycle apparatus is particularly great.

  A control method for a refrigeration cycle apparatus according to the present invention and a refrigeration cycle apparatus using the same, in a refrigeration cycle apparatus provided with an expansion mechanism, appropriately control the number of rotations of the expansion mechanism and stably operate the refrigeration cycle apparatus. In particular, it is possible to improve the stability at the start-up of the refrigeration cycle apparatus.

  A first invention is a refrigeration cycle apparatus having a compression mechanism, a heat source side heat exchanger, an expansion mechanism for recovering power, and a use side heat exchanger, and a first target expansion mechanism rotational speed determined from a discharge temperature of the compression mechanism By controlling the rotation speed of the expansion mechanism so that the discharge temperature does not greatly deviate from the target discharge temperature, it is not necessary to stop the operation of the compression mechanism or the like to protect the refrigeration cycle device, The refrigeration cycle apparatus can be operated stably.

  According to a second invention, in the first invention, in particular, when the discharge temperature of the compression mechanism is higher than a predetermined target discharge temperature, the number of rotations of the expansion mechanism is increased and is lower than the target discharge temperature. If the discharge temperature is higher than the target discharge temperature by reducing the rotation speed of the expansion mechanism, the rotation speed of the expansion mechanism is increased to lower the discharge temperature, and the discharge temperature is lower than the target discharge temperature. In order to protect the refrigeration cycle device, the operation of the compression mechanism is stopped because the rotation speed of the expansion mechanism is decreased and the discharge temperature is raised so that the discharge temperature does not deviate significantly from the target discharge temperature. Therefore, the refrigeration cycle apparatus can be stably operated.

  A third invention is a refrigeration cycle apparatus having a compression mechanism, a heat source side heat exchanger, an expansion mechanism for recovering power, and a use side heat exchanger, wherein the discharge temperature is higher than the target discharge temperature, and the expansion mechanism When the rotation speed of the expansion mechanism exceeds the upper limit value of the use range of the rotation speed of the expansion mechanism, the rotation speed of the expansion mechanism is decreased to reduce the rotation speed of the expansion mechanism. Even if it exists, since discharge temperature can be lowered | hung, in order to protect an expansion mechanism etc., it is not necessary to stop operation | movement of a compression mechanism etc., and a refrigerating-cycle apparatus can be operated stably.

A fourth invention is a refrigeration cycle apparatus having a compression mechanism, a heat source side heat exchanger, an expansion mechanism for recovering power, and a use side heat exchanger, wherein the discharge temperature is lower than the target discharge temperature, and the expansion mechanism If the rotation speed of the expansion mechanism exceeds the lower limit value of the predetermined use range of the rotation speed of the expansion mechanism, the rotation speed of the expansion mechanism is increased so that the rotation speed of the expansion mechanism is smaller than the lower limit rotation speed of use. Even if it exists, since discharge temperature can be raised, it is not necessary to stop operation | movement of a compression mechanism etc. in order to protect an expansion mechanism etc., and a refrigerating-cycle apparatus can be operated stably.

  5th invention is a refrigerating-cycle apparatus provided with the compression mechanism, the heat source side heat exchanger, the expansion mechanism which performs motive power recovery, and the utilization side heat exchanger, at the same time as changing the rotation speed of the compression mechanism or before changing In addition, by changing the rotation speed of the expansion mechanism, it is possible to prevent a rapid change in the high-pressure side pressure when the rotation speed of the compression mechanism changes, and to realize stable start-up of the refrigeration cycle apparatus.

  6th invention is a control method at the time of starting of a refrigerating cycle device provided with a compression mechanism, a heat source side heat exchanger, an expansion mechanism which performs power recovery, and a use side heat exchanger, and flows into the heat source side heat exchanger The rotation speed of the expansion mechanism is maintained for a predetermined time at the second target expansion mechanism rotation speed determined from at least one of the heat source side fluid temperature and the utilization side fluid temperature flowing into the utilization side heat exchanger. The second target expansion mechanism rotation speed is set so that the higher the high pressure side pressure is, the higher the rotation speed is, depending on the outside air temperature and the incoming water temperature. A stable refrigeration cycle apparatus can be activated.

  7th invention is a refrigerating cycle device provided with a compression mechanism, a heat source side heat exchanger, an expansion mechanism which performs power recovery, and a use side heat exchanger, heat source side fluid temperature and use side which flow into a heat source side heat exchanger Maintaining the rotation speed of the expansion mechanism for a predetermined time to the second target expansion mechanism rotation speed determined from at least one of the use-side fluid temperatures flowing into the heat exchanger, and further discharging at least the compression mechanism after a predetermined time has elapsed. The rotational speed of the expansion mechanism is controlled so as to be the first target expansion mechanism rotational speed determined from the temperature. The second target expansion mechanism rotational speed is set so that the rotational speed increases as the pressure on the high pressure side increases more easily according to the outside air temperature and the incoming water temperature. When the rotational speed increases to the mechanism rotational speed, it is possible to prevent a rapid increase in the high-pressure side pressure and to realize a stable start-up of the refrigeration cycle apparatus.

  An eighth invention is a refrigeration cycle apparatus including a compression mechanism, a heat source side heat exchanger, an expansion mechanism for recovering power, and a use side heat exchanger, and the heat source side fluid temperature flowing into the heat source side heat exchanger and the use side Maintaining the rotation speed of the expansion mechanism for a predetermined time to the second target expansion mechanism rotation speed determined from at least one of the use-side fluid temperatures flowing into the heat exchanger, and after a predetermined time has elapsed, the heat source side heat exchanger The rotation speed of the expansion mechanism is controlled to a third target expansion mechanism rotation speed determined from at least one of the heat source side fluid temperature flowing into the heat source side and the utilization side fluid temperature flowing into the utilization side heat exchanger. The rotation speed of the expansion mechanism is controlled so as to be at least the first target expansion mechanism rotation speed determined from the discharge temperature of the compression mechanism. The rotation speed of the expansion mechanism is the second target expansion mechanism rotation speed from the second target expansion mechanism rotation speed. 1 target expansion mechanism It prevents sudden changes in the high-pressure side pressure when increases to rotation number, activation of the stable refrigerating cycle device can be realized while reducing the boot time.

  According to a ninth aspect of the present invention, in any one of the sixth to eighth aspects, it is determined that the predetermined time has ended, particularly if the discharge temperature of the compression mechanism approaches a predetermined target discharge temperature. In addition, it is possible to shorten the time for operation at a low target expansion mechanism rotation speed, and to realize stable start-up of the refrigeration cycle apparatus while further shortening the start-up time.

  According to a tenth aspect of the present invention, in any of the sixth to eighth aspects of the invention, in particular, if the use side fluid temperature flowing into the use side heat exchanger approaches a predetermined target temperature, it is determined that the predetermined time has ended. Therefore, it is possible to shorten the time for operation at an unnecessarily low target expansion mechanism rotation speed, and to realize stable start-up of the refrigeration cycle apparatus while further shortening the start-up time.

In an eleventh aspect of the invention according to any one of the sixth to eighth aspects, in particular, the discharge temperature of the compression mechanism is equal to or greater than a certain temperature difference from a target temperature of the use side fluid temperature flowing into the predetermined use side heat exchanger. If it becomes higher, it is determined that the predetermined time has ended, the time required for operation at an unnecessarily low target expansion mechanism rotational speed can be shortened, and the start-up of the refrigeration cycle apparatus can be stabilized while reducing the start-up time. realizable.

  The twelfth invention is a refrigeration cycle apparatus using the control method of any one of the first to eleventh inventions, and can realize a refrigeration cycle apparatus capable of performing stable start-up and operation.

  The thirteenth aspect of the invention is that in the twelfth aspect of the invention, in particular, the refrigerant is carbon dioxide. In this case, the high-pressure side pressure is likely to increase, and the effect of realizing a stable operation of the refrigeration cycle apparatus is particularly significant. large.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments. For example, in the following embodiment, a hot water heater will be described as an example, but the present invention is not limited to the hot water heater, and may be an air conditioner or the like.

(Embodiment 1)
A control method for the refrigeration cycle apparatus according to the first embodiment of the present invention will be described with reference to the refrigeration cycle apparatus schematically shown in FIG. The refrigeration cycle apparatus of FIG. 1 includes a compression mechanism 2 driven by an electric motor 1, a refrigerant flow path of a radiator 3 as a use side heat exchanger, an expansion mechanism 5 that recovers power by a generator 4, and a heat source side heat exchanger. For example, a refrigerant circuit A in which a CO ₂ refrigerant is enclosed as a refrigerant, a water supply pump 7 as a utilization fluid conveying means, a fluid flow path of the radiator 3, a hot water supply tank 8, and the like. And a fluid circuit B.

  Further, the refrigeration cycle apparatus includes a blower 9 as a heat source fluid transport unit, and the blower 9 blows a heat source fluid (for example, outside air) to the evaporator 6. Further, a compression mechanism control means 10 for controlling the rotational speed of the electric motor 1 and an expansion mechanism control means 11 for controlling the rotational speed of the generator 4 are provided. The expansion mechanism control means 11 can appropriately change the rotation speed of the expansion mechanism 5 according to the state of the refrigeration cycle, for example, the high pressure side pressure, the discharge temperature, and the like.

  Further, the discharge temperature detection means 12 is provided on the refrigerant pipe from the discharge side of the compression mechanism 2 to the refrigerant inlet side of the radiator 3 and detects the discharge temperature of the compression mechanism 2. The outside air temperature detection means 13 as the heat source fluid inlet temperature detection means is fixed to the fins of the evaporator 6 and detects the temperature of the outside air flowing into the evaporator 6. The incoming water temperature detecting means 14 as the used fluid temperature detecting means is provided on the fluid piping from the bottom of the hot water supply tank 8 to the fluid inlet side of the radiator 6, and the used fluid flowing into the radiator 6 (for example, water ) Is detected. The electronic control means 15 determines the state of the refrigeration cycle based on signals from the discharge temperature detection means 12, the outside air temperature detection means 13, the incoming water temperature detection means 14, and the like, and sends it to the compression mechanism control means 10, the expansion mechanism control means 11 and the like. Give instructions.

Next, regarding the operation of the refrigeration cycle apparatus configured as described above, particularly when the change in the refrigeration cycle is small, such as a small change in the outside air temperature or the incoming water temperature, or no instruction from the user. explain. In the refrigerant circuit A, the CO ₂ refrigerant is compressed by the compression mechanism 2 to a pressure exceeding the critical pressure. The compressed refrigerant becomes a high-temperature and high-pressure state, and when it flows through the refrigerant flow path of the radiator 3, it dissipates heat to the water flowing through the fluid flow path of the radiator 3 and is cooled. Thereafter, the refrigerant is depressurized by the expansion mechanism 5 and becomes a low-temperature low-pressure gas-liquid two-phase state. The pressure energy at the time of expansion recovered by the expansion mechanism 5 is transmitted to the generator 4 and recovered as electric power.

  That is, COP can be improved by recovering pressure energy during expansion as power. The refrigerant decompressed by the expansion mechanism 5 is supplied to the evaporator 6. In the evaporator 6, the refrigerant is heated by the outside air sent by the blower 9, and enters a gas-liquid two-phase or gas state. The refrigerant that has flowed out of the evaporator 6 is again sucked into the compression mechanism 2. On the other hand, in the fluid circuit B, the use fluid (for example, water) sent from the bottom of the hot water supply tank 8 to the fluid flow path of the radiator 3 by the water supply pump 7 is heated by the refrigerant flowing through the refrigerant flow path of the radiator 3. The hot fluid (for example, hot water) is stored, and the hot fluid is stored from the top of the hot water supply tank 8. By repeating such a cycle, the refrigeration cycle apparatus of the present embodiment can be used as a water heater.

  Next, a control method will be described. The compression mechanism 2, or the electric motor 1 that is substantially a drive source, includes an outside air temperature detection means 13, an incoming water temperature detection means 14, and the like, a target boiling temperature (a hot water tank) set by a user and the like. Compression so that the rotational speed (hereinafter referred to as the first target compression mechanism rotational speed) calculated by the electronic control unit 15 based on the temperature of hot water stored in the air or the target value of the fluid outlet side temperature of the radiator 6) is obtained. It is controlled by the mechanism control means 10.

  Further, the expansion mechanism 5, substantially the generator 4, is controlled by the expansion mechanism control means 11 as shown in the flowchart of FIG. 2. The electronic control unit 15 uses the outside air temperature detection means 13, the incoming water temperature detection means 14 and the like detected by the outside air temperature, the incoming water temperature, the boiling temperature set by the user (the temperature of hot water stored in the hot water supply tank, or the radiator 6). The target discharge temperature Td0 at which the state of the refrigeration cycle is optimal is calculated from the fluid outlet side temperature) (step 100).

  This target discharge temperature Td0 is set so as not to exceed the use temperature upper limit and pressure upper limit of components such as the compression mechanism 2. Next, the discharge temperature detecting means 12 detects the discharge temperature Td (step 110). It is determined whether or not the detected discharge temperature Td is higher than a value obtained by adding a certain value ΔT1 to the target discharge temperature Td0 (step 120). Note that ΔT1 is a minute value that is added so that the discharge temperature Td falls within a certain temperature range in order to increase the stability of the state of the refrigeration cycle.

  If it is determined in step 120 that the discharge temperature Td is higher than Td0 + ΔT1, it is determined in step 130 whether or not the rotation speed Reexp of the expansion mechanism 5 is higher than the upper limit rotation speed Reexp_max of the expansion mechanism 5. . The upper limit rotation speed Reexp_max of the expansion mechanism 5 is set as an upper limit value for protecting the expansion mechanism 5 and the expansion mechanism control means 11. If it is determined in step 130 that the rotation speed Reexp of the expansion mechanism 5 is smaller than the upper limit rotation speed Reexp_max, the expansion is performed so that the rotation speed of the expansion mechanism 5 and the generator 4 is increased by a certain amount. The mechanism control means 11 is instructed (step 140). Thereby, since the refrigerant | coolant amount which distribute | circulates the expansion mechanism 5 increases, discharge temperature Td and a high voltage | pressure side pressure can be reduced.

  If it is determined in step 120 that the discharge temperature Td is lower than Td0 + ΔT1, it is determined in step 150 whether or not the discharge temperature Td is smaller than a value obtained by subtracting a certain value ΔT2 from the target discharge temperature Td0. Note that ΔT2 is a minute value that is decreased so that the discharge temperature Td falls within a certain temperature range in order to increase the stability of the state of the refrigeration cycle. If it is determined in step 150 that the discharge temperature Td is lower than Td0−ΔT2, it is determined in step 160 whether or not the rotation speed Reexp of the expansion mechanism 5 is smaller than the lower limit rotation speed Reexp_min of the expansion mechanism 5. judge.

The lower limit rotation speed Reexp_min of the expansion mechanism 5 is set as a lower limit value for protecting the expansion mechanism 5 and the expansion mechanism control means 11. If it is determined in step 160 that the rotation speed Reexp of the expansion mechanism 5 is greater than the use lower limit rotation speed Reexp_min,
The expansion mechanism control means 11 is instructed to decrease the rotation speeds of the expansion mechanism 5 and the generator 4 by a certain amount (step 170). Thereby, since the refrigerant | coolant amount which distribute | circulates the expansion mechanism 5 falls, discharge temperature Td and a high voltage | pressure side pressure can be raised.

  If it is determined in step 120 that the discharge temperature Td is lower than Td0 + ΔT1, and it is determined in step 150 that the discharge temperature Td is higher than Td0−ΔT2, the discharge temperature is a certain temperature close to the target discharge temperature Td0. Since it is within the range, the expansion mechanism control means 11 is instructed to maintain the current expansion mechanism 5 and the rotational speed of the generator 4 (step 180).

  On the other hand, if it is determined in step 120 that the discharge temperature Td is higher than Td0 + ΔT1, and it is determined in step 130 that the rotation speed Reexp of the expansion mechanism 5 is larger than the upper limit rotation speed Reexp_max, the expansion mechanism is further increased. Increasing the number of revolutions of 5 may cause a decrease in reliability. Therefore, the compression mechanism control unit 10 is instructed to reduce the number of revolutions of the compression mechanism 2 and the electric motor 1 by a certain amount (step 190). ). Thereby, the discharge temperature Td and the high-pressure side pressure can be reduced without exceeding the upper limit rotation speed Reexp_max of the expansion mechanism 5.

  In step 120, it is determined that the discharge temperature Td is lower than Td0 + ΔT1, and in step 150, it is determined that the discharge temperature Td is lower than Td0−ΔT2, and in step 160, the rotation speed Reexp of the expansion mechanism 5 is the lower limit rotation speed Reexp_min. If it is determined that the rotational speed of the expansion mechanism 5 is further reduced, the reliability of the compression mechanism 2 and the electric motor 1 may be reduced by a certain amount. The compression mechanism control means 10 is instructed to increase (step 200). Thereby, the discharge temperature Td and the high-pressure side pressure can be increased without exceeding the lower limit rotation speed Reexp_min of the expansion mechanism 5.

  According to the operations from step 120 to step 180 described above, when the discharge temperature Td exceeds the upper limit value (Td0 + ΔT1) of the target discharge temperature, the rotation speed of the expansion mechanism 5 and the generator 4 is changed to be increased. Since the discharge temperature Td is lowered, it is not necessary to stop the operation of the compression mechanism 2 or the like in order to protect the refrigeration cycle apparatus, and the refrigeration cycle apparatus can be stably operated. Further, when the discharge temperature Td is lower than the lower limit value (Td0−ΔT2) of the target discharge temperature, the expansion mechanism 5 and the generator 4 are changed so as to decrease the rotation speed, and the discharge temperature Td is increased. Therefore, the refrigeration cycle apparatus can be stably operated without unnecessarily lowering the discharge temperature Td. The target expansion mechanism rotational speed of the expansion mechanism 5 determined by the operations of steps 120 to 180 is hereinafter referred to as a first target expansion mechanism rotational speed.

  Further, according to the operations of Steps 190 to 200, when the discharge temperature Td exceeds the upper limit value (Td0 + ΔT1) of the target discharge temperature and the rotation speed Reexp of the expansion mechanism 5 is larger than the use upper limit rotation speed Reexp_max, Instead of increasing the rotation speed of the expansion mechanism 5 and the generator 4 and decreasing the discharge temperature Td, the rotation speed of the compression mechanism 2 and the electric motor 1 is decreased and the discharge temperature Td is decreased. There is no need to stop the operation of the compression mechanism 2 or the like to protect the mechanism 5 or the like, and the refrigeration cycle apparatus can be stably operated.

When the discharge temperature Td is lower than the lower limit value (Td0−ΔT2) of the target discharge temperature and the rotation speed Reexp of the expansion mechanism 5 is smaller than the use lower limit rotation speed Reexp_min, the expansion mechanism 5 and the generator In order to protect the expansion mechanism 5 and the like, the rotation speed of the compression mechanism 2 and the electric motor 1 is increased and the discharge temperature Td is increased instead of lowering the rotation speed 4 and increasing the discharge temperature Td. There is no need to stop the operation of the compression mechanism 2 and the like, and the refrigeration cycle apparatus can be stably operated.

  Obviously, even if the operations in steps 190 to 200 are omitted, the effects of the operations in steps 120 to 180 can be obtained. Further, it is clear that even if one of the operations of Step 190 and Step 200 is omitted, the effect of the operation of the step that is not omitted can be obtained.

  ΔT1 and ΔT2 may be the same value or different values. Furthermore, one or both of ΔT1 and ΔT2 may be set to zero.

(Embodiment 2)
The control method at the time of starting of the refrigeration cycle apparatus in the second embodiment of the present invention, the time chart shown in FIG. 3, the flowchart of the control of the expansion mechanism 5 shown in FIG. 4, the control of the compression mechanism 2 shown in FIG. This will be described with reference to a flowchart. The schematic configuration of the refrigeration cycle apparatus is the same as that shown in FIG.

  When an instruction from the user or a predetermined operation time is reached, the electronic control device 15 activates the refrigeration cycle device. In the present embodiment, the expansion mechanism 5 is activated before the compression mechanism 2 is activated. The expansion mechanism 5, substantially the generator 4, is controlled by the expansion mechanism control means 11, as shown in the flowchart of FIG. The electronic control unit 15 detects the outside air temperature by the outside air temperature detecting means 13 (Step 300), and detects the incoming water temperature by the incoming water temperature detecting means 14 (Step 310). A second target expansion mechanism rotational speed that is the rotational speed of the expansion mechanism 5 at the time of starting the refrigeration cycle apparatus is calculated from the detected outside air temperature, incoming water temperature, and the like (step 320). The second target expansion mechanism rotational speed is such that the higher the outside air temperature is, the higher the rotational speed is and the incoming water temperature is such that the operating temperature upper limit and pressure upper limit of the components such as the compression mechanism 2 and the expansion mechanism 5 are not exceeded at startup. A value smaller than the first target expansion mechanism rotation speed described in the first embodiment is set so that the higher the rotation speed, the higher the rotation speed.

  Next, the expansion mechanism 5 is operated (activated) at the second target expansion mechanism rotation speed (step 330). Further, it is determined whether a predetermined time Te1 has elapsed after the expansion mechanism 5 is activated (step 340). If the predetermined time Te1 has not elapsed, the process returns to step 330, and the operation at the second target expansion mechanism rotational speed is continued. On the other hand, when the predetermined time Te1 has elapsed, the process proceeds to steps 100 to 200 in the flowchart of FIG. 2 described in the first embodiment, and the operation is performed at the first target expansion mechanism rotational speed.

  On the other hand, the compression mechanism 2, substantially the electric motor 1 as a drive source, is controlled by the compression mechanism control means 10 as shown in the flowchart of FIG. The electronic control unit 15 detects the outside air temperature by the outside air temperature detecting means 13 (step 400), and detects the incoming water temperature by the incoming water temperature detecting means 14 (step 410). A second target compression mechanism rotational speed that is the rotational speed of the compression mechanism 2 at the time of starting the refrigeration cycle apparatus is calculated from the detected outside air temperature, incoming water temperature, and the like (step 420). The second target compression mechanism rotational speed does not exceed the upper use temperature limit and the upper pressure limit of components such as the compression mechanism 2 and the expansion mechanism 5 at the time of start-up, and is the first described in the first embodiment. A value smaller than the target compression mechanism rotational speed is set.

Thereby, it is possible to prevent a decrease in reliability such as lack of lubricating oil that may occur when the rotation speed of the compression mechanism 2 is suddenly increased from a stopped state at the time of startup. Next, it is determined whether a predetermined time T0 has elapsed since the expansion mechanism 5 was activated (step 430). If the predetermined time T0 has not elapsed, the process returns to step 400, the detection of the outside air temperature and the incoming water temperature is updated, and the calculation of the second target compression mechanism rotation speed is updated. When the predetermined time T0 has elapsed, the compression mechanism 2 is operated (activated) at the second target compression mechanism rotation speed (step 440).

  Next, it is determined whether a predetermined time Tc1 has elapsed after the compression mechanism 2 is activated (step 450). If the predetermined time Tc1 has not elapsed, the process returns to step 440, and the operation at the second target compression mechanism rotational speed is continued. On the other hand, when the predetermined time Tc1 has elapsed, the outside air temperature detecting means 13 detects the outside air temperature again (step 460), and the incoming water temperature detecting means 14 detects the incoming water temperature (step 470). A first target compression mechanism rotational speed, which is the rotational speed of the compression mechanism 2 when the refrigeration cycle apparatus is stable, is calculated from the detected outside air temperature, incoming water temperature, and the like (step 480).

  The first target compression mechanism rotational speed is set so that a necessary heating amount can be secured when the refrigeration cycle is relatively stable. The predetermined time Tc1 is set to a value greater than (predetermined time Te1-predetermined time T0). Next, the rotation speed of the compression mechanism 2 is changed to the first target compression mechanism rotation speed (step 490). Thereafter, the process returns to step 460, and the update of the detection of the outside air temperature and the incoming water temperature and the update of the calculation of the first target compression mechanism rotation speed are repeated at a predetermined control cycle, and another instruction, for example, a stop instruction of the refrigeration cycle apparatus Until then, the operation at the first target compression mechanism rotational speed is continued.

  According to the above operation, as shown in the time chart of FIG. 2, after the expansion mechanism 5 is started at the second target expansion mechanism rotational speed calculated from the outside air temperature and the incoming water temperature, after the predetermined time T0 has elapsed, the compression mechanism 2 starts at the second target compression mechanism rotation speed calculated from the outside air temperature and the incoming water temperature. For this reason, when the compression mechanism 2 is started, a stable start of the refrigeration cycle apparatus can be realized without causing problems such as a rapid increase in the high-pressure side pressure because the expansion mechanism 5 is stopped. The second target expansion mechanism rotation speed is set so that the higher the high pressure side pressure is, the higher the rotation speed is, depending on the outside air temperature and the incoming water temperature. The rise can be prevented, and a stable refrigeration cycle apparatus can be started.

  When the predetermined time Tc1 elapses after the compression mechanism 2 is activated, the rotation speed of the compression mechanism 2 increases to the first target compression mechanism rotation speed calculated from the outside air temperature and the incoming water temperature. When the predetermined time Te1 has elapsed, the rotational speed of the expansion mechanism 5 is increased in advance to the first target expansion mechanism rotational speed described in the first embodiment. As described above, since the rotation speed of the expansion mechanism 5 is set to be increased in advance before the rotation speed of the compression mechanism 2 is increased, the rapid high pressure side when the rotation speed of the compression mechanism 2 is increased is set. An increase in pressure can be prevented, and a stable refrigeration cycle apparatus can be started.

  In the present embodiment, it has been described that the rotation speed of the expansion mechanism 5 is increased before the rotation speed of the compression mechanism 2 is increased. However, at the same time as the rotation speed of the compression mechanism 2 is increased, the expansion mechanism 5 is increased. The same effect can be obtained even when the number of rotations is increased (that is, T0 is set to 0).

  Further, in the present embodiment, the first target expansion mechanism rotation speed, the second target expansion mechanism rotation speed, and the like are determined according to the outside air temperature and the incoming water temperature, but according to any one of the temperatures. It may be determined.

In the present embodiment, the first target compression mechanism rotation speed that is the target rotation speed of the compression mechanism 2 and the first target expansion mechanism that is the target rotation speed of the expansion mechanism 5 when the change in the refrigeration cycle is small. Before reaching the rotational speed, the second target compression mechanism rotational speed and the second target compression mechanism rotational speed set to a rotational speed smaller than those are provided, the first target compression mechanism rotational speed, and A plurality of second target compressions are performed so that the section before reaching the first target expansion mechanism rotational speed is divided into a plurality of sections and the target compression mechanism rotational speed and the target expander rotational speed are changed stepwise. A mechanism rotational speed and a second target expansion mechanism rotational speed may be provided (Embodiment 3).
A control method at the start of the refrigeration cycle apparatus according to the third embodiment of the present invention will be described with reference to a time chart shown in FIG. 6 and a flowchart of control of the expansion mechanism 5 shown in FIG. The schematic configuration of the refrigeration cycle apparatus is the same as that shown in FIG. Moreover, since the control method of the compression mechanism 2 is the same as that of 2nd Embodiment, description is abbreviate | omitted.

  When an instruction from the user or a predetermined operation time is reached, the electronic control device 15 activates the refrigeration cycle device. In the present embodiment, the expansion mechanism 5 is activated before the compression mechanism 2 is activated. The expansion mechanism 5, substantially the generator 4, is controlled by the expansion mechanism control means 11, as shown in the flowchart of FIG. The electronic control unit 15 detects the outside air temperature by the outside air temperature detecting means 13 (step 500), and detects the incoming water temperature by the incoming water temperature detecting means 14 (step 510). A second target expansion mechanism rotational speed that is the rotational speed of the expansion mechanism 5 at the time of starting the refrigeration cycle apparatus is calculated from the detected outside air temperature, incoming water temperature, and the like (step 520). The second target expansion mechanism rotational speed is such that the higher the outside air temperature is, the higher the rotational speed is and the incoming water temperature is such that the operating temperature upper limit and pressure upper limit of the components such as the compression mechanism 2 and the expansion mechanism 5 are not exceeded at startup. A value smaller than the first target expansion mechanism rotation speed described in the first embodiment is set so that the higher the rotation speed, the higher the rotation speed.

  Next, the expansion mechanism 5 is operated (activated) at the second target expansion mechanism rotation speed (step 530). Further, it is determined whether a predetermined time Te2 has elapsed after the expansion mechanism 5 is started (step 540). If the predetermined time Te2 has not elapsed, the process returns to step 530, and the operation at the second target expansion mechanism rotational speed is continued. On the other hand, when the predetermined time Te2 has elapsed, the detection of the outside air temperature is updated by the outside air temperature detecting means 13 (step 550), and the detection of the incoming water temperature is updated by the incoming water temperature detecting means 14 (step 560).

  A third target expansion mechanism rotational speed that is the rotational speed of the expansion mechanism 5 at the time of starting the refrigeration cycle apparatus is calculated from the detected outside air temperature, incoming water temperature, and the like (step 570). The third target expansion mechanism rotational speed is such that the higher the outside air temperature is, the higher the rotational speed is, and the incoming water temperature is such that the operating temperature upper limit and pressure upper limit of the components such as the compression mechanism 2 and the expansion mechanism 5 are not exceeded at startup. It is set to a value larger than the first target expansion mechanism rotation speed described in the first embodiment so that the higher the rotation speed, the higher the rotation speed.

  Next, the expansion mechanism 5 is operated at the third target expansion mechanism rotation speed (step 580). Further, it is determined whether a predetermined time Te3 has elapsed after the expansion mechanism 5 is activated (step 590). If the predetermined time Te3 has not elapsed, the process returns to step 550, and after updating the detection of the outside air temperature and the incoming water temperature and calculating the third target expansion mechanism rotational speed again, the third target expansion mechanism rotational speed is reached. Continue driving. On the other hand, when the predetermined time Te3 has elapsed, the process proceeds to steps 100 to 200 in the flowchart of FIG. 2 described in the first embodiment, and the operation is performed at the first target expansion mechanism rotational speed.

  According to the above operation, as shown in the time chart of FIG. 6, when the expansion mechanism 5 is started at the second target expansion mechanism rotation speed calculated from the outside air temperature and the incoming water temperature, when the predetermined time Te3 has elapsed, the expansion mechanism 5 The rotational speed of 5 increases to the first target expansion mechanism rotational speed described in the first embodiment. However, when the predetermined time Te2 elapses before the predetermined time Te3 elapses, the rotation speed of the expansion mechanism 5 is operated at the third target expansion mechanism rotation speed set to a value larger than the second target expansion mechanism rotation speed. Therefore, it is possible to prevent a rapid change in the high-pressure side pressure when the rotation speed of the expansion mechanism 5 increases from the second target expansion mechanism rotation speed to the first target expansion mechanism rotation speed, and to stabilize the startup time. Activation of the refrigeration cycle apparatus can be realized.

  In the present embodiment, the third target expansion mechanism rotational speed is determined according to the outside air temperature and the incoming water temperature, but may be determined according to any one of the temperatures.

(Embodiment 4)
A control method at the start of the refrigeration cycle apparatus according to the fourth embodiment of the present invention will be described with reference to a control flowchart of the expansion mechanism 5 shown in FIG. 8, the same control steps as those in FIG. 7 are denoted by the same reference numerals, and description thereof is omitted. The schematic configuration of the refrigeration cycle apparatus is the same as that shown in FIG. Furthermore, since the control method of the compression mechanism 2 is the same as that of the second embodiment, description thereof is omitted.

  In step 580, the expansion mechanism 5 is operated at the third target expansion mechanism rotation speed, and it is further determined whether a predetermined time Te3 has elapsed after the expansion mechanism 5 is started (step 590). If the predetermined time Te3 has not elapsed, the discharge temperature detecting means 12 detects the discharge temperature Td (step 600). It is determined whether or not the difference between the target discharge temperature Td0 and the detected discharge temperature Td is smaller than a certain value ΔT3 (step 610). As in the first embodiment, the target discharge temperature Td0 is the outside air temperature, the incoming water temperature, the target boiling temperature set by the user (the temperature of hot water stored in the hot water tank, or the fluid of the radiator 6). From the target value of the outlet side temperature), the refrigeration cycle state is set to be optimal, and ΔT3 is a minute value for determining that the discharge temperature Td has approached the target discharge temperature Td0.

  If it is determined in step 610 that the difference between the target discharge temperature Td0 and the detected discharge temperature Td is greater than a certain value ΔT3, the discharge temperature Td is not sufficiently close to the target discharge temperature Td0, so Returning again, after updating the detection of the outside air temperature and the incoming water temperature and calculating the third target expansion mechanism rotation speed, the operation at the third target expansion mechanism rotation speed is continued. On the other hand, when it is determined that the difference between the target discharge temperature Td0 and the detected discharge temperature Td is smaller than a certain value ΔT3, the discharge temperature Td is sufficiently close to the target discharge temperature Td0. The process proceeds to steps 100 to 200 in the flowchart of FIG. 2 described in the embodiment, and the operation is performed at the first target expansion mechanism rotation speed that is the rotation speed of the expansion mechanism 5 that brings the discharge temperature close to the target discharge temperature.

  If it is determined in step 590 that the predetermined time Te3 has elapsed, the process proceeds to steps 100 to 200 in the flowchart of FIG. 2 described in the first embodiment, and the operation is performed at the first target expansion mechanism rotational speed. To do.

  According to the above operation, even if the predetermined time Te3 has not elapsed, when the discharge temperature Td approaches the target discharge temperature Td0, the next target expansion mechanism rotation is performed as in the case where the predetermined time Te3 has elapsed. The number will shift. That is, when the discharge temperature Td approaches the target discharge temperature Td0, it is considered that the predetermined time Te3 has elapsed.

  According to such an operation, even before the predetermined time Te3 has elapsed, when the discharge temperature Td approaches the target discharge temperature Td0, the rotation speed of the expansion mechanism 5 becomes the first target expansion mechanism rotation speed. Since the shift is made, it is possible to unnecessarily reduce the time for operation at the third target expansion mechanism rotation speed, and to realize stable start-up of the refrigeration cycle apparatus while reducing the start-up time.

In the present embodiment, when the discharge temperature Td approaches the target discharge temperature Td0, it is assumed that the predetermined time Te3 has elapsed, but it flows out of the radiator 3 that is the use side heat exchanger. If the use side fluid outlet temperature (that is, boiling temperature) approaches the target temperature (that is, target boiling temperature) of the predetermined use side fluid outlet temperature, it may be considered that the predetermined time Te3 has elapsed. Good. Alternatively, if the discharge temperature Td is higher than a predetermined target boiling temperature by a certain temperature difference or more, it may be considered that the predetermined time Te3 has elapsed. ΔT3 may be 0.

  Further, also in the predetermined times Te1, Te2, Tc1, etc. in the second to third embodiments, when the discharge temperature Td approaches the target discharge temperature Td0, or when the boiling temperature approaches the target boiling temperature, Even when the discharge temperature Td becomes higher than the target boiling temperature by a certain temperature difference or more, it may be considered that each predetermined time has passed.

When the refrigerant is a CO ₂ refrigerant, the high-pressure side pressure is a pressure in a supercritical state that does not depend on the condensation temperature, and thus the high-pressure side pressure tends to increase. According to the above embodiment, Therefore, stable operation of the refrigeration cycle apparatus can be realized without stopping the operation of the compression mechanism to protect the equipment.

  A control method for a refrigeration cycle apparatus according to the present invention and a refrigeration cycle apparatus using the same, in a refrigeration cycle apparatus provided with an expansion mechanism, appropriately control the number of rotations of the expansion mechanism and stably operate the refrigeration cycle apparatus. Therefore, it can be applied to uses such as a water heater and an air conditioner equipped with an expansion mechanism.

The block diagram which shows the refrigerating-cycle apparatus in Embodiment 1-4 of this invention. Flowchart of control of expansion mechanism in Embodiment 1 of the present invention Time chart of control in Embodiment 2 of the present invention Flowchart of control of expansion mechanism in embodiment 2 of the present invention Flowchart of control of compression mechanism in Embodiment 2 of the present invention Time chart of control in Embodiment 3 of the present invention Flowchart of control of expansion mechanism in Embodiment 3 of the present invention Flowchart of control of expansion mechanism in embodiment 4 of the present invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Electric motor 2 Compression mechanism 3 Use side heat exchanger (heat radiator)
4 Generator 5 Expansion mechanism 6 Heat source side heat exchanger (evaporator)
7 Fluid transport means (water supply pump)
8 Hot water tank 9 Heat source fluid transfer means (blower)
DESCRIPTION OF SYMBOLS 10 Compression mechanism control means 11 Expansion mechanism control means 12 Discharge temperature detection means 13 Outside air temperature detection means 14 Incoming water temperature detection means 15 Electronic control means 15
A Refrigerant circuit B Fluid circuit

Claims (13)

In a refrigeration cycle apparatus including at least a compression mechanism, a heat source side heat exchanger, an expansion mechanism that performs power recovery, and a use side heat exchanger, at least a first target expansion mechanism rotational speed determined from a discharge temperature of the compression mechanism And controlling the number of rotations of the expansion mechanism. When the discharge temperature of the compression mechanism is higher than a predetermined target discharge temperature, the rotation speed of the expansion mechanism is increased. When the discharge temperature of the compression mechanism is lower than the target discharge temperature, the rotation speed of the expansion mechanism is decreased. The control method of the refrigerating-cycle apparatus of Claim 1 characterized by the above-mentioned. In a refrigeration cycle apparatus including at least a compression mechanism, a heat source side heat exchanger, an expansion mechanism for recovering power, and a use side heat exchanger, the discharge temperature of the compression mechanism is higher than a predetermined target discharge temperature. When the rotation speed of the expansion mechanism exceeds a predetermined upper limit value of the use range of the rotation speed of the expansion mechanism, the rotation speed of the compression mechanism is reduced. . In a refrigeration cycle apparatus including at least a compression mechanism, a heat source side heat exchanger, an expansion mechanism for recovering power, and a use side heat exchanger, the discharge temperature of the compression mechanism is lower than a predetermined target discharge temperature. When the rotation speed of the expansion mechanism exceeds a predetermined lower limit value of the use range of the rotation speed of the expansion mechanism, the rotation speed of the compression mechanism is increased. . In a refrigeration cycle apparatus including at least a compression mechanism, a heat source side heat exchanger, an expansion mechanism for recovering power, and a use side heat exchanger, the expansion is performed at the same time as or before the rotation speed of the compression mechanism is changed. A control method for a refrigeration cycle apparatus, wherein the number of rotations of the mechanism is changed. At least a compression mechanism, a heat source side heat exchanger, an expansion mechanism for recovering power, and a control method at the time of start-up of a refrigeration cycle apparatus including a use side heat exchanger, the heat source side fluid flowing into the heat source side heat exchanger A refrigeration characterized in that the rotation speed of the expansion mechanism is maintained for a predetermined time at a second target expansion mechanism rotation speed determined from at least one of a temperature and a utilization side fluid temperature flowing into the utilization side heat exchanger. Control method for cycle equipment. In a refrigeration cycle apparatus including at least a compression mechanism, a heat source side heat exchanger, an expansion mechanism for recovering power, and a use side heat exchanger, the heat source side fluid temperature flowing into the heat source side heat exchanger and the use side heat exchanger The rotation speed of the expansion mechanism is maintained for a predetermined time to the second target expansion mechanism rotation speed determined from at least one of the use-side fluid temperatures flowing into the gas, and after a predetermined time has passed, at least the discharge temperature of the compression mechanism A control method for a refrigeration cycle apparatus, wherein the rotation speed of the expansion mechanism is controlled so as to be a first target expansion mechanism rotation speed determined from In a refrigeration cycle apparatus including at least a compression mechanism, a heat source side heat exchanger, an expansion mechanism for recovering power, and a use side heat exchanger, the heat source side fluid temperature flowing into the heat source side heat exchanger and the use side heat exchanger The rotation speed of the expansion mechanism is maintained for a predetermined time to the second target expansion mechanism rotation speed determined from at least one of the use side fluid temperatures flowing into the heat source, and after the predetermined time has passed, the heat source side heat exchanger The rotation speed of the expansion mechanism is controlled to a third target expansion mechanism rotation speed determined from at least one of the flowing heat source side fluid temperature and the utilization side fluid temperature flowing into the utilization side heat exchanger. Thereafter, the rotation speed of the expansion mechanism is controlled so as to be at least a first target expansion mechanism rotation speed determined from the discharge temperature of the compression mechanism. The control of the refrigeration cycle apparatus according to any one of claims 6 to 8, wherein when the discharge temperature of the compression mechanism approaches a predetermined target discharge temperature, it is determined that the predetermined time has ended. Method. 9. The apparatus according to claim 6, wherein the predetermined time is determined to have ended when a use side fluid temperature flowing into the use side heat exchanger approaches a predetermined target temperature. Method for controlling the refrigeration cycle apparatus. If the discharge temperature of the compression mechanism is higher than a predetermined target temperature of the use side fluid temperature flowing into the use side heat exchanger, the predetermined time is determined to have ended. The control method of the refrigerating-cycle apparatus of any one of Claims 6-8 to do. A refrigeration cycle apparatus using the control method according to any one of claims 1 to 11. The refrigeration cycle apparatus according to claim 12, wherein the refrigerant is carbon dioxide.

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