JP5573370B2 - Refrigeration cycle apparatus and control method thereof - Google Patents

Description

  The present invention relates to a refrigeration cycle apparatus provided with a supercooling circuit for exchanging heat between a refrigerant flowing in a main refrigerant circuit and a refrigerant flowing in a bypass circuit.

  Conventionally, in this type of refrigeration cycle apparatus, the opening degree of the bypass flow rate control means is set to an initial opening degree so that the degree of superheat of the refrigerant at the outlet on the bypass side is equal to or lower than a predetermined degree of superheat, and after the compressor is started, The bypass flow rate is controlled so that the degree of superheat of the refrigerant at the bypass side outlet becomes a predetermined degree of superheat (see, for example, Patent Document 1).

  FIG. 2 shows a cycle configuration diagram of a conventional refrigeration cycle apparatus described in Patent Document 1. As shown in FIG. As shown in FIG. 2, a main refrigerant circuit formed by connecting a compressor 21, a heat source side heat exchanger 23, indoor expansion valves 29 a to 29 d, and use side heat exchangers 30 a to 30 d, and a heat source side heat exchanger 23. A subcooling heat exchanger 26 for exchanging heat between the refrigerant flowing in the main refrigerant circuit and the refrigerant flowing in the bypass circuit 28 at the outlet, bypass flow rate control means 27 for controlling the bypass flow rate of the bypass circuit 28, and bypass And a superheat degree detecting means 36 for detecting the superheat degree at the side outlet.

Japanese Patent No. 2936961

  However, in the conventional configuration, after the compressor is started, the bypass flow rate is controlled based on the detected value so that the superheat degree of the refrigerant at the bypass side outlet becomes a predetermined superheat degree. When the refrigerant state suddenly changes greatly, there is a problem that the control of the bypass flow rate control means is not in time and excessive liquid return is generated from the bypass circuit.

  For example, in a low outside air temperature condition or a high outside air temperature condition in which a large capacity difference occurs between the use side heat exchanger and the heat source side heat exchanger, the heat source side heat exchanger is subjected to heat exchange in order to maintain the refrigeration cycle state appropriately. In some cases, the fluid transporting means for transporting the fluid is controlled to be repeatedly stopped / operated. At this time, the refrigerant state at the inlet of the bypass control unit may change abruptly due to the stop / operation of the fluid transfer unit that transfers the heat exchange fluid to the heat source side heat exchanger.

  The present invention solves the above-mentioned conventional problems, and prevents excessive liquid return from the bypass circuit even under conditions where the fluid conveying means for conveying the heat exchange fluid to the heat source side heat exchanger stops. In addition, an object of the present invention is to provide a refrigeration cycle apparatus that can expand a range in which the refrigeration cycle apparatus can be stably operated by using a supercooling heat exchanger and a control method thereof.

In order to solve the above-described conventional problems, the refrigeration cycle apparatus of the present invention includes a main refrigerant circuit formed by connecting a compressor, a heat source side heat exchanger, a supercooling heat exchanger, a throttle mechanism, and a use side heat exchanger. When,
Branching between the heat source side heat exchanger and the supercooling heat exchanger or between the supercooling heat exchanger and the throttle mechanism, the compression via the bypass flow rate control means and the supercooling heat exchanger A bypass circuit connected to the suction side of the compressor , a fluid conveying means for conveying the heat exchange fluid to the heat source side heat exchanger, and a control for controlling at least the compressor, the bypass flow rate control means, and the fluid conveying means comprising apparatus and, wherein the control device, in cooling operation the utilization-side heat exchanger acts as an evaporator, the bypass flow rate control means so that the degree of superheat of the refrigerant at the outlet of the bypass circuit becomes a predetermined value Since the ability of the heat source side heat exchanger becomes excessive as compared with the ability of the use side heat exchanger even if the rotational speed of the fluid conveying means is reduced and the normal control to be controlled, the fluid conveying means is stopped. When the opening degree of the bypass flow rate control means definitive when stopping of the fluid conveyance means, closes predetermined opening than the opening degree of the bypass flow rate control means in the normal control immediately before stopping the fluid conveying means, said While the fluid transfer means is stopped, at least the control for maintaining the bypass flow rate control means in the state where the predetermined opening degree is closed is executed .

  As a result, even if the pressure at the inlet of the bypass flow control means suddenly rises due to the stop of the fluid transfer means that transfers the heat exchange fluid to the heat source side heat exchanger, the opening degree of the bypass flow control means is predetermined. By closing the opening degree in advance, it is possible to prevent the amount of bypass from becoming excessive and causing liquid return from the bypass circuit.

  The refrigeration cycle apparatus of the present invention and its control method prevent excessive liquid return from the bypass circuit even under conditions where the fluid transfer means for transferring the heat exchange fluid to the heat source side heat exchanger repeatedly stops / operates. In addition, the range in which the refrigeration cycle apparatus can be stably operated can be expanded using the supercooling heat exchanger and the bypass circuit.

Cycle configuration diagram of refrigeration cycle apparatus in Embodiment 1 of the present invention Flowchart during cooling operation in Embodiment 1 of the present invention Cycle configuration diagram of conventional refrigeration cycle equipment

A first invention includes a main refrigerant circuit formed by connecting a compressor, a heat source side heat exchanger, a supercooling heat exchanger, a throttle mechanism, and a use side heat exchanger, the heat source side heat exchanger, and the supercooling. A bypass circuit branched from a heat exchanger or from between the supercooling heat exchanger and the throttle mechanism, and connected to a suction side of the compressor via a bypass flow rate control means and the supercooling heat exchanger; a fluid conveying means for conveying the Hinetsu exchange fluid to the heat source-side heat exchanger, and a control unit for controlling the at least the compressor and the bypass flow rate control means and the fluid conveying means, wherein the control device In the cooling operation in which the use side heat exchanger acts as an evaporator, normal control for controlling the bypass flow rate control means so that the degree of superheat of the refrigerant at the outlet of the bypass circuit becomes a predetermined value, and the fluid conveying means Reduce the rotation speed of If the capacity of the heat source-side heat exchanger is stopped the fluid transfer means to become excessive as compared with the capacity of the use side heat exchanger also, the bypass flow rate definitive when stopping of the fluid conveyance means The opening degree of the control means is closed by a predetermined opening degree than the opening degree of the bypass flow rate control means in the normal control immediately before stopping the fluid transfer means, and during the stop of the fluid transfer means, the bypass flow rate control means And at least a control for maintaining the closed state of the predetermined opening , thereby preventing excessive liquid return from the bypass circuit even in a condition where the fluid conveying means is stopped to maintain the refrigeration cycle. can do.

In addition, when the fluid conveying means is stopped, the bypass flow control means maintains the state when the fluid conveying means is stopped, so that the bypass flow control means is opened too much while the fluid conveying means is stopped. A range in which the refrigeration cycle can be stably operated using the supercooling heat exchanger and the bypass circuit while preventing excessive liquid return from the bypass circuit when the fluid conveying means is operated again. Can be spread.

According to a second aspect of the invention, in particular, in the first aspect of the invention , when the control unit stops the fluid transfer unit in the cooling operation, the bypass flow rate is determined after a predetermined time has elapsed from the restart of the operation of the fluid transfer unit. By setting the opening according to the load to the control means, the fluid conveying means is operated without being temporarily affected by the pressure change that occurs immediately after the fluid conveying means resumes operation. Since the opening degree of the bypass flow control means can be controlled in the refrigerant state at the inlet of the bypass flow control means, the supercooling heat exchanger can be used more effectively.

In the third invention, in particular, in the first or second invention , the fluid conveying means is a fan so that the heat exchange fluid is a gas such as air and is easily synchronized with the rotational speed of the fan. Control can be performed.

In the fourth invention, in particular, in the first or second invention , the fluid conveying means is a pump, so that the heat exchange fluid is a liquid such as water and is easily synchronized with the operation frequency of the pump. Control can be performed.

The fifth invention includes a main refrigerant circuit formed by connecting a compressor, a heat source side heat exchanger, a supercooling heat exchanger, a throttle mechanism, and a use side heat exchanger, the heat source side heat exchanger, and the supercooling. A bypass circuit branched from a heat exchanger or from between the supercooling heat exchanger and the throttle mechanism, and connected to a suction side of the compressor via a bypass flow rate control means and the supercooling heat exchanger; A refrigeration cycle apparatus comprising: a fluid conveyance means for conveying a heat exchange fluid to the heat source side heat exchanger; and a control device for controlling at least the compressor, the bypass flow rate control means, and the fluid conveyance means . , In the cooling operation in which the use side heat exchanger acts as an evaporator,
The bypass flow rate control means is controlled so that the degree of superheat of the refrigerant at the outlet of the bypass circuit becomes a predetermined value, and the capacity of the heat source side heat exchanger remains the use side heat even if the rotational speed of the fluid conveying means is reduced. when stopping the fluid transfer means to become excessive as compared with the exchanger capacity, the opening degree of the bypass flow rate control means definitive when stopping of the fluid conveying means, just before stopping the fluid conveying means Control is performed so that the bypass flow rate control means maintains the closed state of the predetermined opening while the fluid conveying means is stopped while the fluid conveyance means is stopped. Accordingly, excessive liquid return from the bypass circuit can be prevented even under a condition in which the fluid conveying means is stopped to maintain the refrigeration cycle.

In addition, when the fluid conveying means is stopped, the bypass flow control means maintains the state when the fluid conveying means is stopped, so that the bypass flow control means is opened too much while the fluid conveying means is stopped. A range in which the refrigeration cycle can be stably operated using the supercooling heat exchanger and the bypass circuit while preventing excessive liquid return from the bypass circuit when the fluid conveying means is operated again. Can be spread.

In a sixth aspect of the invention, in particular, in the fifth aspect of the invention , when the control device stops the fluid conveying means in the cooling operation, the bypass flow rate is determined after a predetermined time has elapsed since the operation of the fluid conveying means resumed. By setting the opening according to the load to the control means, the fluid conveying means is operated without being temporarily affected by the pressure change that occurs immediately after the fluid conveying means resumes operation. Since the opening degree of the bypass flow control means can be controlled in the refrigerant state at the inlet of the bypass flow control means, the supercooling heat exchanger can be used more effectively.

  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.

(Embodiment 1)
FIG. 1 shows a cycle configuration diagram of a refrigeration cycle apparatus according to a first embodiment of the present invention. This refrigeration cycle apparatus includes an outdoor unit including the heat source side heat exchanger 3 and the like, an indoor unit including the use side heat exchanger 10a and the like, and a connecting pipe connecting them.

  In FIG. 1, a compressor 1, a heat source side heat exchanger 3, a supercooling heat exchanger 6, indoor expansion valves 9a and 9b that function as a throttle mechanism during cooling operation, and use side heat exchangers 10a and 10b are connected to each other. A refrigerant circuit is formed. The main refrigerant circuit includes an outdoor expansion valve 5 that acts as a throttle device during heating operation.

  Further, this refrigeration cycle apparatus branches from between the supercooling heat exchanger 6 and the indoor expansion valves 9a and 9b, and is connected to the suction side of the compressor 1 via the bypass flow rate control means 7 and the supercooling heat exchanger 6. , A heat source side heat exchanger fan 4 as fluid conveying means for conveying the heat exchange fluid to the heat source side heat exchanger 3, and a control device 13.

  The main refrigerant circuit is provided with a four-way valve 2 for switching between cooling operation and heating operation. A sub-accumulator 12 is provided between the four-way valve 2 and the suction pipe of the compressor 1, a discharge pressure detection means 14 is provided for the discharge pipe of the compressor 1, and a suction pressure detection means is provided for the suction pipe of the compressor 1. 15 are provided. The bypass circuit 8 is provided with bypass side outlet temperature detection means 16 for detecting the temperature of the bypass side outlet. A main refrigerant circuit side outlet temperature detection means 17 is provided in the piping between the indoor expansion valves 9 a and 9 b of the main refrigerant circuit and the supercooling heat exchanger 6.

  Furthermore, indoor fans 11a and 11b are provided in the vicinity of the use side heat exchangers 10a and 10b as fluid transfer means for transferring the heat exchange fluid.

  In addition, the refrigerant | coolant used for a refrigerating-cycle apparatus can use pseudo-azeotropic mixed refrigerant | coolants, such as R410A, or a single refrigerant | coolant of a freon refrigerant system or a natural refrigerant system, for example.

  In the refrigeration cycle apparatus configured as described above, by switching the four-way valve 2, a cooling operation in which the refrigerant flows in the direction of the solid line arrow in FIG. 1 and a heating operation in which the refrigerant flows in the direction of the broken line arrow in FIG. And can be switched. Hereinafter, the state change of the refrigerant during the cooling operation will be described as an example.

  The high-pressure refrigerant discharged from the compressor 1 flows into the heat source side heat exchanger 3 acting as a radiator through the four-way valve 2 and radiates heat to the air conveyed by the heat source side heat exchanger fan 4. The high-pressure refrigerant flowing out from the heat source side heat exchanger 3 flows into the supercooling heat exchanger 6 through the outdoor expansion valve 5 and is supercooled by the low-pressure refrigerant decompressed by the bypass flow rate control means 7. The high-pressure refrigerant flowing out of the supercooling heat exchanger 6 is divided into the main refrigerant circuit side where the indoor expansion valves 9a and 9b are located and the bypass circuit 8 side where the bypass flow rate control means 7 is located. The high-pressure refrigerant branched to the main refrigerant circuit is decompressed and expanded by the indoor expansion valves 9a and 9b, then flows into the use-side heat exchangers 10a and 10b acting as an evaporator, and is conveyed by the indoor fans 11a and 11b. It absorbs heat by exchanging heat with air.

  On the other hand, the high-pressure refrigerant divided into the bypass circuit 8 is decompressed and expanded by the bypass flow rate control means 7 and then flows into the supercooling heat exchanger 6. The low-pressure refrigerant that has flowed into the supercooling heat exchanger 6 is heated by the high-pressure refrigerant that has flowed out of the heat source side heat exchanger 3. Thereafter, the low-pressure refrigerant that has flowed out of the supercooling heat exchanger 6 merges with the low-pressure refrigerant that has flowed out of the use-side heat exchangers 10a and 10b, and is sucked into the compressor 1 again.

  Thus, by using the supercooling heat exchanger 6, the degree of supercooling of the refrigerant diverted to the main refrigerant circuit side can be increased, and from the outdoor unit to the indoor unit including the use side heat exchangers 10a and 10b. Even if the connecting pipe becomes longer, the generation of flash gas due to the effect of pressure loss is prevented, and a sufficient liquid refrigerant is supplied to the use side heat exchangers 10a and 10b, so that a stable cooling operation is performed.

  Hereinafter, the control operation will be described in detail.

  In the present embodiment, the discharge pressure detecting means 14 for detecting the discharge pressure of the compressor 1, the suction pressure detecting means 15 for detecting the suction pressure, and the bypass side outlet temperature detecting means 16 for detecting the bypass side outlet temperature are provided. Is provided.

  The control device 13 calculates the saturation temperature from the detection value of the discharge pressure detection means 14, calculates the saturation temperature Tc from that value, calculates the saturation temperature from the detection value of the suction pressure detection means 15, and sets the value as the evaporation temperature Te. Detected. Further, the control device 13 calculates the degree of superheat at the bypass side outlet from the difference between the detected temperature of the bypass side outlet temperature detecting means 16 and the evaporation temperature Te. Alternatively, the degree of supercooling of the main refrigerant circuit side outlet is calculated from the difference between the detected temperature of the main refrigerant circuit side outlet temperature detection means 17 and the condensation temperature Tc.

  In normal control, in order to balance the capacities of the use-side heat exchangers 10a and 10b and the heat-source-side heat exchanger 3, the heat-source-side heat exchanger fan 4 reduces the number of rotations rpm and performs heat-source-side heat exchange. Control is performed to suppress the capacity of the vessel 3. Specifically, the rotation speed rpm of the heat source side heat exchanger fan 4 is increased or decreased so that the condensation temperature Tc is a predetermined value.

  On the other hand, the opening degree of the bypass flow rate control means 7 is controlled so that the degree of superheat at the bypass side outlet becomes a predetermined value in order to prevent liquid return from the bypass circuit 8. Alternatively, the degree of superheating at the bypass side outlet may be maintained at a predetermined value or more, and the degree of supercooling at the main refrigerant circuit side outlet may be controlled to be a predetermined value.

  By performing the normal control as described above, the degree of supercooling at the outlet of the main refrigerant circuit of the supercooling heat exchanger 6 is ensured, and even if the connecting pipe is long, the generation of flash gas is suppressed, and the use side heat exchanger 10a. A stable refrigeration cycle can be maintained by supplying liquid refrigerant stably to 10b.

  However, when the number of indoor units is small and the capacity of the heat source side heat exchanger 3 is easy to obtain, the heat source side heat exchanger can be used even if the rotation speed rpm of the heat source side heat exchanger fan 4 is set to the lower limit value R_min. 3 becomes excessive, the condensing temperature and the evaporating temperature are lowered, and the use side heat exchangers 10a and 10b are frozen due to the lowering of the evaporating temperature, or the discharge pressure and the suction pressure of the compressor 1 are lowered. As a result, problems such as failure to keep the allowable operating pressure range of the compressor 1 occur.

  In order to avoid the occurrence of such a situation, the heat source side heat exchanger fan 4 is stopped to prevent the discharge pressure of the compressor 1 from being equal to or lower than the first predetermined value Tc_1 and the second predetermined value Tc_2. Then, the heat source side heat exchanger fan 4 is operated again, and the discharge pressure and the suction pressure of the compressor 1 are controlled so as to be within a predetermined range.

  In the situation where the heat source side heat exchanger fan 4 is repeatedly stopped / operated as described above, the refrigerant state at the inlet of the bypass flow rate control means 7 is suddenly affected by the stop / operation of the heat source side heat exchanger fan 4. Therefore, if the bypass flow rate control means 7 remains in normal control, liquid return is caused from the bypass circuit 8.

  Hereinafter, a state in which liquid return occurs from the bypass circuit 8 in a situation where the heat source side heat exchanger fan 4 repeatedly stops / operates during normal control of the bypass flow rate control means 7 will be described.

  Immediately after the heat source side heat exchanger fan 4 is stopped from operation, the condensation pressure increases, so that the degree of supercooling at the inlet of the bypass flow rate control means 7 increases, and the heat source side heat exchanger fan 4 operates. If the opening degree of the bypass flow rate control means 7 is the same as before because the pressure on the primary side of the bypass flow rate control means 7 suddenly increases compared to the time, the bypass flow rate flowing through the bypass circuit 8 becomes excessive and the liquid returns. Will occur.

  In addition, if the heat source side heat exchanger fan 4 continues to be stopped, heat exchange is not performed in the heat source side heat exchanger 3, so that the degree of supercooling rapidly decreases at the inlet of the bypass flow rate control means 7, The refrigerant state is a two-phase state. If the opening of the bypass flow rate control means 7 is the same as compared with the case where the refrigerant state at the previous inlet was in the liquid phase, the bypass flow rate is Since the degree of superheat at the outlet on the bypass side increases and the degree of supercooling on the outlet on the main refrigerant circuit side decreases, the normal opening of the bypass flow rate control means 7 controls the opening degree to open.

  Since this state continues while the heat source side heat exchanger fan 4 is stopped, the opening degree of the bypass flow rate control means 7 is set so that the heat source side heat exchanger fan 4 is stopped in a normal control operation. Will continue to be controlled in the opening direction, so it will open to near the upper limit.

Thereafter, when the heat source side heat exchanger fan 4 is operated again, the condensing pressure suddenly decreases, whereby the dryness at the inlet of the bypass flow rate control means 7 once increases, but the heat source side heat exchanger fan 4 Since the heat exchange is continued in the heat source side heat exchanger 3, the inlet of the bypass flow rate control means 7 eventually becomes a liquid phase, and the bypass flow rate control is performed while the heat source side heat exchanger fan 4 is stopped. If the means 7 is open to the vicinity of the upper limit value, the bypass flow rate becomes excessive and liquid return occurs.

  In the present embodiment, in order to prevent liquid return from the bypass circuit 8 described above, when the heat source side heat exchanger fan 4 is stopped, the opening degree of the bypass flow rate control means 7 is closed by a predetermined opening degree, The opening degree is maintained until the exchanger fan 4 is operated and a predetermined time elapses, and normal control is performed when the predetermined time elapses.

  Hereinafter, the operation when the cooling operation is performed will be described with reference to the flowchart shown in FIG.

  First, the condensation temperature Tc is calculated based on the pressure detected by the discharge pressure detecting means 14, and the normal control of the heat source side heat exchanger fan 4 is performed so that the condensation temperature Tc is set to a predetermined value (step S1). .

  Next, in order to prevent liquid return from the bypass circuit 8, the normal control of the bypass flow rate control means 7 is performed so that the degree of superheat at the outlet on the bypass side becomes a predetermined value (step S2). That is, the degree of superheat at the bypass side outlet is controlled to be a predetermined value. Alternatively, the degree of superheating at the bypass side outlet may be maintained at a predetermined value or more, and the degree of supercooling at the main refrigerant circuit side outlet may be controlled to be a predetermined value. Here, the degree of superheat at the bypass side outlet is the difference between the detected temperature of the bypass side outlet temperature detecting means 16 and the saturation temperature of the detected value of the suction pressure detecting means 15, and the degree of supercooling at the main refrigerant circuit side outlet is: It is calculated by the difference between the saturation temperature of the detected value of the discharge pressure detecting means 14 and the detected temperature of the main refrigerant circuit side outlet temperature detecting means 17.

  Next, the condensation temperature Tc, the evaporation temperature Te, and the rotation speed rpm of the heat source side heat exchanger fan 4 are detected (step S3), the condensation temperature Tc is less than the predetermined first value Tc_1, and the evaporation temperature Te is less than the predetermined value Te_1. In addition, it is determined whether or not the rotation speed rpm of the heat source side heat exchanger fan 4 is the minimum rotation speed R_min (step S4).

  If the condition is satisfied, the heat source side heat exchanger fan 4 is stopped (step S5). If the condition is not satisfied, the heat source side heat exchanger fan 4 returns to step S1 and repeats the normal control.

  If the heat source side heat exchanger fan 4 is stopped, the bypass flow rate control means 7 is closed by a predetermined opening and maintained in that state (step S6). Thereafter, the condensation temperature Tc is detected again (step S7), and it is determined whether the condensation temperature Tc is equal to or higher than the second predetermined value Tc_2 (step S8).

  If the condensation temperature Tc is less than the second predetermined value Tc_2, the process returns to the detection stage of the condensation temperature Tc (step S7) while maintaining the state. If the condensation temperature Tc is equal to or higher than the second predetermined value Tc_2, the rotation speed rpm of the heat source side heat exchanger fan 4 is started at the lower limit value R_min (step S9), and then the heat source side heat exchanger fan 4 is condensed to the condensation temperature Tc. The normal control is performed so that is set to a predetermined value (step 10).

  Next, it is determined whether or not a predetermined time has elapsed since the heat source side heat exchanger fan 4 is started (step 11). If the predetermined time has not elapsed, the heat source side heat exchanger fan 4 is operated under normal control. Returning to the step (step 10), if the predetermined time has elapsed, the step returns to the step (step S2) in which the bypass flow rate control means 7 is normally controlled, and the control operation is repeated.

  As described above, in the present embodiment, when the heat source side heat exchanger fan 4 is stopped, the bypass flow rate control means 7 is closed by a predetermined opening from the opening immediately before the heat source side heat exchanger fan 4 is stopped, and the heat source side From the time when the heat exchanger fan 4 resumes operation until the predetermined time elapses, the opening degree of the bypass flow rate control means 7 maintains the state when the heat source side heat exchanger fan 4 is stopped, whereby the heat source side heat exchange is performed. Even in a situation where the functional fan 4 is repeatedly stopped / operated, it is possible to prevent the opening of the bypass flow rate control means 7 from being opened excessively and causing liquid return from the bypass circuit 8.

  Further, even in a situation where the heat source side heat exchanger fan 4 repeatedly stops / runs, by using the supercooling heat exchanger 6 and the bypass circuit 8 while preventing excessive liquid return from the bypass circuit 8, A sufficient degree of supercooling at the main refrigerant circuit side outlet of the subcooling heat exchanger 6 can be secured to supply liquid refrigerant stably to the use side heat exchangers 10a and 10b, or the supercooling heat exchanger 6 By using as an evaporator, the range in which the refrigeration cycle can be stably operated can be expanded.

  Moreover, in this Embodiment, the bypass flow control means 7 is set to control according to load after predetermined time progress from the driving | operation start of the heat source side heat exchanger fan 4. FIG. Specifically, after a predetermined time has elapsed from the start of operation of the heat source side heat exchanger fan 4, control is performed so that the degree of superheat at the bypass side outlet becomes a predetermined value, or the degree of superheat at the bypass side outlet is equal to or greater than a predetermined value. And the supercooling degree at the main refrigerant circuit side outlet is controlled to be a predetermined value. Thus, the bypass flow rate control means 7 in a state in which the heat source side heat exchanger fan 4 is operated without being temporarily affected by the pressure change that occurs immediately after the heat source side heat exchanger fan 4 resumes operation. Since the opening degree of the bypass flow rate control means 7 can be controlled in the refrigerant state at the inlet, the supercooling heat exchanger can be used more effectively.

  In the present embodiment, the bypass circuit 8 branches off from between the subcooling heat exchanger 6 and the indoor expansion valves 9a and 9b as the throttle mechanism, but the heat source side heat exchanger 3 and the subcooling heat. You may branch from between the exchangers 6. Although the cooling operation has been described, even in the heating operation in which the four-way valve 2 is switched to use the heat source side heat exchanger 3 as an evaporator and the use side heat exchangers 10a and 10b as radiators, Since the heat source side heat exchanger fan 4 is controlled so as to be stopped / operated repeatedly in order to suppress the increase in the temperature, the same effect as in the cooling operation can be obtained.

  As described above, the refrigeration cycle apparatus and the control method thereof according to the present invention provide a circuit from the bypass circuit even under the condition that the fluid conveying means for conveying the heat exchange fluid to the heat source side heat exchanger repeatedly stops / operates. By preventing excessive liquid back and using a supercooling heat exchanger and a bypass circuit, the range in which the refrigeration cycle can be stably operated can be expanded.

  Accordingly, a difference in performance between the heat source side heat exchanger and the use side heat exchanger occurs, and it is necessary to perform control such that the fluid conveying means for conveying the heat exchange fluid to the heat source side heat exchanger is stopped / repeated. For heat pump hot water heaters and heat source machines that have a supercooling circuit to exchange heat between the refrigerant flowing in the main refrigerant circuit and the refrigerant flowing in the bypass circuit that can be used up to low or high outside air temperatures Can also be adapted.

DESCRIPTION OF SYMBOLS 1 Compressor 3 Heat source side heat exchanger 4 Fan for heat source side heat exchanger 5 Outdoor expansion valve 6 Subcooling heat exchanger 7 Bypass flow control means 8 Bypass circuit 9a, 9b Indoor expansion valve 10a, 10b Use side heat exchanger 13 Control Device 15 Suction pressure detection means 16 Bypass side outlet temperature detection means 17 Main refrigerant circuit side outlet temperature detection means

Claims (6)

A main refrigerant circuit formed by connecting a compressor, a heat source side heat exchanger, a supercooling heat exchanger, a throttle mechanism, and a use side heat exchanger;
Branching between the heat source side heat exchanger and the supercooling heat exchanger or between the supercooling heat exchanger and the throttle mechanism, the compression via the bypass flow rate control means and the supercooling heat exchanger A bypass circuit connected to the suction side of the machine,
Fluid conveying means for conveying the heat exchange fluid to the heat source side heat exchanger;
And a control unit for controlling the at least the compressor and the bypass flow rate control means and the fluid conveying means,
In the cooling operation in which the use side heat exchanger acts as an evaporator, the control device,
Normal control for controlling the bypass flow rate control means so that the degree of superheat of the refrigerant at the outlet of the bypass circuit becomes a predetermined value;
When the fluid conveying means is stopped because the capacity of the heat source side heat exchanger is excessive compared with the capacity of the user side heat exchanger even if the rotational speed of the fluid conveying means is reduced, the fluid conveying means is stopped. the opening degree of the bypass flow rate control means definitive when stopping means, closing predetermined opening than the opening degree of the bypass flow rate control means in the normal control immediately before stopping the fluid conveying means, during the stop of the fluid conveyance means Is a control for maintaining the bypass flow rate control means closed at the predetermined opening;
A refrigeration cycle apparatus that executes at least The control device sets the bypass flow rate control means to an opening degree corresponding to a load after a predetermined time has elapsed after restarting the operation of the fluid conveyance means when the fluid conveyance means is stopped in the cooling operation. The refrigeration cycle apparatus according to claim 1 , wherein: The refrigeration cycle apparatus according to claim 1 or 2 , wherein the fluid conveying means is a fan. The refrigeration cycle apparatus according to claim 1 or 2 , wherein the fluid conveying means is a pump. A main refrigerant circuit formed by connecting a compressor, a heat source side heat exchanger, a supercooling heat exchanger, a throttle mechanism, and a use side heat exchanger;
Branching between the heat source side heat exchanger and the supercooling heat exchanger or between the supercooling heat exchanger and the throttle mechanism, the compression via the bypass flow rate control means and the supercooling heat exchanger A bypass circuit connected to the suction side of the machine,
Fluid conveying means for conveying the heat exchange fluid to the heat source side heat exchanger;
In a refrigeration cycle apparatus comprising at least a control device for controlling the compressor, the bypass flow rate control means, and the fluid conveying means ,
In the cooling operation in which the control device acts as an evaporator with the use side heat exchanger,
Controlling the bypass flow rate control means so that the degree of superheat of the refrigerant at the outlet of the bypass circuit becomes a predetermined value;
When the fluid conveying means is stopped because the capacity of the heat source side heat exchanger is excessive compared with the capacity of the user side heat exchanger even if the rotational speed of the fluid conveying means is reduced, the opening degree of the bypass flow rate control means definitive when stopping the conveying means, closes predetermined opening than the opening degree of the bypass flow rate control means in the normal control immediately before stopping the fluid conveying means, stopping of the fluid conveyance means The control method for the refrigeration cycle apparatus , wherein the control is performed so that the bypass flow rate control means maintains the closed state of the predetermined opening . When the control device stops the fluid conveying means in the cooling operation, the controller sets the bypass flow rate control means to an opening degree corresponding to a load after a predetermined time has elapsed since the resumption of the operation of the fluid conveying means. The method for controlling a refrigeration cycle apparatus according to claim 5 , wherein: