JPWO2012032699A1 - Refrigeration cycle equipment - Google Patents

Abstract

The refrigeration cycle apparatus 100 of the present invention includes a compressor 101, a condenser (102 or 106), a first throttle device (103 or 105), a gas-liquid separator 104, a second throttle device (105 or 103), and A refrigerant circuit 160 including an evaporator (106 or 102), an injection path 170 for supplying the gas-phase refrigerant separated by the gas-liquid separator 104 to the compressor 101 during the compression process, and a first in the refrigerant circuit 160 Detection means 130 for detecting the temperature or pressure of the refrigerant existing downstream of the expansion device and upstream of the second expansion device or in the injection passage 170, and during the start-up operation, defrost operation or stop operation, the gas-liquid When the detection means 130 detects that the pressure of the refrigerant flowing into the separator 104 exceeds a predetermined pressure lower than the saturated vapor pressure, the first And a control device 108 for reducing the opening degree of the throttle device.

Description

  The present invention relates to a refrigeration cycle apparatus that injects refrigerant into a compressor during the compression process.

  Conventionally, a refrigeration cycle apparatus that injects refrigerant into a compressor during the compression process is known. According to such a refrigeration cycle apparatus, the heating capacity can be improved.

  For example, Patent Document 1 discloses a refrigeration cycle apparatus 850 as shown in FIG. In this refrigeration cycle apparatus 850, the gas-phase refrigerant separated by the gas-liquid separator 855 is injected into the injection cylinder 851a of the compressor 851 through the injection path 859. The injection path 859 is provided with an injection throttle device 860. And if the injection through the injection path 859 is performed, the heating capability in the condenser 852 will improve.

  Further, Patent Document 2 discloses a refrigeration cycle apparatus 900 similar to the refrigeration cycle apparatus 850 of Patent Document 1 as shown in FIG. In the refrigeration cycle apparatus 900, carbon dioxide is used as a refrigerant, and a throttling device is not provided in the injection path 902 for injection into the compressor 901.

JP-A 61-197960 Japanese Patent Laid-Open No. 11-173687

  By the way, in the gas-liquid separator, it is ideal that the gas-phase refrigerant and the liquid-phase refrigerant are completely separated, but in the transition period such as the start-up operation, the gas-liquid separator uses the gas-phase refrigerant and the liquid-phase separator. The refrigerant may not be completely separated, and the liquid phase refrigerant may be mixed in the gas phase refrigerant. Such a phenomenon becomes more prominent as the pressure in the gas-liquid separator is closer to the saturated vapor pressure. For this reason, there exists a possibility that a liquid phase refrigerant | coolant may be injected into a compressor with a gaseous-phase refrigerant | coolant through an injection path. When such injection of the liquid phase refrigerant into the compressor occurs excessively, liquid compression in the compressor becomes a problem.

  Therefore, at the time of start-up operation, it is conceivable to close the expansion device 860 provided in the injection path 859 as disclosed in Patent Document 1, but in this way, at the time of start-up operation, the heating capacity is improved by injection. The effect is not obtained.

  Note that the phenomenon that the liquid-phase refrigerant is mixed into the gas-phase refrigerant as described above also occurs in the defrost operation and the stop operation.

  In the refrigeration cycle apparatus 900 of Patent Document 2, carbon dioxide that is in a supercritical state on the high-pressure side is used as a refrigerant, and thus the above phenomenon is unlikely to be a problem. That is, Patent Document 2 does not disclose or suggest the technical idea of preventing the liquid phase refrigerant from being injected into the compressor through the injection path.

  In view of such circumstances, the present invention provides a refrigeration cycle apparatus capable of suppressing liquid compression without blocking an injection path even when a refrigerant that does not enter a supercritical state on the high pressure side is used. With the goal.

  In order to solve the above problems, the present invention provides a compressor that compresses a refrigerant, a condenser that condenses the refrigerant compressed by the compressor, a first throttle device that expands the refrigerant condensed by the condenser, A gas-liquid separator that separates the refrigerant expanded in the first expansion device into a gas-phase refrigerant and a liquid-phase refrigerant, a second expansion device that expands the liquid-phase refrigerant separated in the gas-liquid separator, and the first A refrigerant circuit including an evaporator for evaporating the refrigerant expanded by the throttle device of 2, wherein the refrigerant circuit circulates a refrigerant that does not enter a supercritical state after being compressed by the compressor, and the gas separated by the gas-liquid separator. An injection path for supplying phase refrigerant to the compressor in the course of the compression process, and downstream of the first expansion device in the refrigerant circuit and upstream of the second expansion device or in the injection path Existing refrigerant The detection means for detecting temperature or pressure, and the detection means that the pressure of the refrigerant flowing into the gas-liquid separator has exceeded a predetermined pressure lower than the saturated vapor pressure during start-up operation, defrost operation or stop operation. A refrigeration cycle device comprising: a control device that reduces the opening of the first throttling device when detected.

  According to the refrigeration cycle apparatus of the present invention, the compressor is adjusted by adjusting the opening of the first throttle device so that the pressure of the refrigerant flowing into the gas-liquid separator is equal to or lower than the predetermined pressure lower than the saturated vapor pressure. The amount of liquid-phase refrigerant injected into the liquid can be suppressed to such an extent that liquid compression does not become a problem. Thereby, even if it does not interrupt | block an injection path, liquid compression can be suppressed in the case of a starting operation, a defrost operation, or a stop operation.

Configuration diagram of a refrigeration cycle apparatus according to Embodiment 1 of the present invention. Mollier diagram of the refrigeration cycle in Embodiment 1 of the present invention The flowchart which shows the control method in Embodiment 1 of this invention. Mollier diagram for explaining the effect of the control in the first embodiment of the present invention Graph for explaining the relationship between the pressure of the refrigerant flowing into the gas-liquid separator and the flow rate of the gas-phase refrigerant injected into the compressor Configuration diagram of a refrigeration cycle apparatus according to Embodiment 2 of the present invention The flowchart which shows the control method in Embodiment 2 of this invention. Configuration diagram of a refrigeration cycle apparatus according to Embodiment 3 of the present invention The flowchart which shows the control method in Embodiment 3 of this invention. The flowchart which shows the control method in another embodiment of this invention. The flowchart which shows the control method in another embodiment of this invention. Configuration diagram of the refrigeration cycle apparatus for explaining the first normal operation Mollier diagram of the refrigeration cycle in the first normal operation Flow chart showing the control method in the first normal operation Mollier diagram for explaining the effect of control in the first normal operation Configuration diagram of the refrigeration cycle apparatus for explaining the second normal operation Flow chart showing the control method in the second normal operation Configuration diagram of the refrigeration cycle apparatus for explaining the third normal operation Flow chart showing the control method in the third normal operation Configuration diagram of the refrigeration cycle apparatus for explaining the fourth normal operation Flow chart showing a control method in the fourth normal operation Configuration diagram of conventional refrigeration cycle equipment Configuration diagram of conventional refrigeration cycle equipment

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.

(Embodiment 1)
The configuration of the refrigeration cycle apparatus 100 according to Embodiment 1 of the present invention will be described with reference to FIG. Although the refrigeration cycle apparatus 100 configured as an air conditioner will be described in the present embodiment, the refrigeration cycle apparatus of the present invention can be applied to a hot water supply apparatus and the like. FIG. 1 shows a configuration for suppressing liquid compression during start-up operation. As shown in FIG. 1, the refrigeration cycle apparatus 100 of the present embodiment includes a refrigerant circuit 160 that circulates a refrigerant and an injection path 170.

  The refrigerant circuit 160 is a circuit for circulating the refrigerant. The refrigerant circuit 160 includes a compressor 101, an indoor heat exchanger 102, an indoor expansion device 103, a gas-liquid separator 104, an outdoor expansion device 105, an outdoor heat exchanger 106, and a four-way valve 120 (switching in claims) Equivalent to the device). The four-way valve 120 is for switching between heating operation and cooling operation. The first port of the four-way valve 120 is connected to the discharge port of the compressor 101 by piping, and the fourth port of the four-way valve 120 is connected to the suction port of the compressor 101 by piping. The second port of the four-way valve 120 is connected to the third port via piping through the indoor heat exchanger 102, the indoor expansion device 103, the gas-liquid separator 104, the outdoor expansion device 105, and the outdoor heat exchanger 106. Has been.

  The injection path 170 is a passage for supplying the gas-phase refrigerant separated by the gas-liquid separator 104 to the compressor 101 during the compression process. The injection path 170 is provided with a temperature sensor 130 (corresponding to detection means in the claims) that detects the temperature of the refrigerant flowing through the injection path 170.

  In the present embodiment, a refrigerant that does not become a supercritical state after being compressed by the compressor 101 is used as the refrigerant. An example of such a refrigerant is a fluorocarbon refrigerant.

  Furthermore, the refrigeration cycle apparatus 100 includes a control device 108. The control device 108 mainly controls the rotation speed of the compressor 101, the opening degree of the indoor side expansion device 103 and the opening degree of the outdoor side expansion device 105, and the four-way valve 120. The present embodiment is characterized in that the control device 108 controls the opening degree of the indoor expansion device 103 and the opening degree of the outdoor expansion device 105 based on the detection value of the temperature sensor 130. Detailed control will be described later.

  Next, the flow of the refrigerant in the refrigerant circuit 160 will be described. During the heating operation, the four-way valve 120 is switched to the state in which the refrigerant flows in the direction indicated by the solid line shown in FIG. 1, and during the cooling operation, the four-way valve is switched to the state in which the refrigerant flows in the direction indicated by the broken line shown in FIG. .

  During the heating operation, the refrigerant compressed by the compressor 101 is condensed in the indoor heat exchanger 102. The refrigerant condensed in the indoor heat exchanger 102 expands in the indoor expansion device 103. The refrigerant expanded in the indoor expansion device 103 is separated into a gas-phase refrigerant and a liquid-phase refrigerant in the gas-liquid separator 104. The liquid phase refrigerant separated by the gas-liquid separator 104 expands in the outdoor expansion device 105. The refrigerant expanded in the outdoor expansion device 105 evaporates in the outdoor heat exchanger 106. The refrigerant evaporated in the outdoor heat exchanger 106 is sucked into the compressor 101. In this case, the indoor heat exchanger 102 functions as a condenser and the outdoor heat exchanger 106 functions as an evaporator.

  During the cooling operation, the refrigerant circulates in the order of the compressor 101, the outdoor heat exchanger 106, the outdoor expansion device 105, the gas-liquid separator 104, the indoor expansion device 103, and the indoor heat exchanger 102. In this case, the indoor heat exchanger 102 functions as an evaporator and the outdoor heat exchanger 106 functions as a condenser.

  Next, the state of the refrigerant flowing through the refrigerant circuit 160 and the injection path 170 will be described using the Mollier diagram of FIG. Hereinafter, the indoor heat exchanger 102 during the heating operation or the outdoor heat exchanger 106 during the cooling operation will be described as a condenser, and the indoor heat exchanger 102 during the cooling operation or the outdoor heat exchanger 106 during the heating operation will be described as an evaporator. To do. Further, the indoor side expansion device 103 during the heating operation or the outdoor side expansion device 105 during the cooling operation (that is, the expansion device upstream of the gas-liquid separator 104) is used as the first expansion device, and the indoor side during the cooling operation. The expansion device 103 or the outdoor expansion device 105 during heating operation (that is, the expansion device downstream of the gas-liquid separator 104) will be described as a second expansion device. This point is the same in the second and third embodiments described later and other embodiments.

  The low-pressure refrigerant (state A) sucked into the compressor 101 is compressed to an intermediate pressure (state B), merges with the refrigerant supplied from the injection passage 170 (state C), and then further compressed to a high temperature. High pressure (state D). The high-temperature and high-pressure refrigerant discharged from the compressor 101 flows into the condenser, where it is cooled and condensed (state E). The high-pressure refrigerant that has flowed out of the condenser is expanded by the first throttling device to an intermediate pressure (state F). This refrigerant is separated in the gas-liquid separator 104 into a refrigerant mainly composed of a gas-phase refrigerant (state I) and a liquid-phase refrigerant (state G). A refrigerant mainly composed of a gas phase refrigerant flows into the injection path 170. The liquid phase refrigerant flows into the second expansion device. The liquid-phase refrigerant that has flowed into the second expansion device further expands to become a low-pressure refrigerant (state H). Thereafter, the low-pressure refrigerant evaporates in the evaporator to become a gas state (state A), then passes through the four-way valve 120 and is sucked into the compressor 101 again. The refrigerant mainly composed of the gas-phase refrigerant separated in the gas-liquid separator 104 passes through the injection path 170 and is sucked into the compressor 101 during the compression process.

  Note that the refrigerant separated in the gas-liquid separator 104 and flowing into the injection passage 170 ideally does not contain a liquid phase component (that is, the state J in FIG. 2), but the gas phase component and the liquid phase component. May not be completely separated. That is, in FIG. 2, the state I may move to the left side of the saturated vapor line. In the start-up operation as in the present embodiment, this problem appears remarkably.

  The mixing of the liquid-phase refrigerant into the gas-phase refrigerant in the gas-liquid separator 104 is more noticeable as the pressure of the refrigerant flowing into the gas-liquid separator 104 shown in the state F of FIG. 2 is closer to the saturated vapor pressure. Therefore, in order to suppress the amount of the liquid phase component in the refrigerant whose main component is the gas phase refrigerant separated in the gas-liquid separator 104, the pressure in the state F in FIG. It is effective to keep the pressure below a predetermined pressure (for example, 1.25 MPa (when the refrigerant is R410A)) lower than the pressure at the intersection of the minute EF and the saturated liquid line. In this way, the gas phase component of the refrigerant (state I) flowing through the injection path 170 increases and the liquid phase component decreases (state I moves to the right in FIG. 2). Thereby, the liquid compression in the compressor 101 is suppressed.

  In the present embodiment, the control device 108 detects the first throttle device when the temperature sensor 130 detects that the pressure of the refrigerant flowing into the gas-liquid separator 104 exceeds a predetermined pressure during the start-up operation. The opening degree of the second throttle device is increased while the opening degree is reduced. This will be specifically described below with reference to the flowchart of FIG. This control may be performed while the output of the compressor 101 is kept constant, or may be performed while the output of the compressor 101 is changed. Further, the control may be performed in parallel with the control of other devices.

  The control device 108 starts the operation by starting the operation after setting the opening of the first expansion device and the opening of the second expansion device to a predetermined opening.

  First, the control device 108 determines the magnitude relationship between the time T elapsed from the start of operation and a threshold T1 (for example, 5 minutes) (step S201). If the relationship of T> T1 is established (YES in step S201), the process proceeds to step S202 and the start-up operation is terminated. If the relationship of T> T1 is not satisfied (NO in step S201), the process proceeds to step S211 and the startup operation is continued. The time T that has elapsed since the start of operation can be measured by a timer 109 attached to the control device 108.

  In step S202, a transition operation is performed to set the opening of the first throttling device and the opening of the second throttling device to an opening suitable for normal operation, and then the process proceeds to step S203 to perform normal operation.

  In step S211, the temperature sensor 130 detects the temperature Ti of the refrigerant flowing through the injection path 170.

  Next, the control device 108 determines the magnitude relationship between the temperature Ti and a predetermined threshold value Ti1 (for example, 10 ° C.) (step S212). In the present embodiment, when the relationship of Ti> Ti1 is established, control device 108 determines that the pressure of the refrigerant flowing into gas-liquid separator 104 has exceeded a predetermined pressure lower than the saturated vapor pressure. If the relationship of Ti> Ti1 is established (YES in step S212), the opening degree of the first throttling device is decreased by ΔA1 and the opening degree of the second throttling device is increased by ΔA2 (step S213). Return to S201. If the relationship of Ti> Ti1 is not satisfied (NO in step S212), the process returns to step S201. That is, the control device 108 monitors Ti during the start-up operation, and if Ti is larger than Ti1, the opening of the first throttling device is gradually decreased and the second throttling device until Ti becomes Ti1 or less. Gradually increase the opening.

  According to the control based on the flowchart of FIG. 3, the opening degree of the first throttling device can be reduced and the opening degree of the second throttling device can be increased based on the temperature of the refrigerant in the injection passage 170. Thereby, the pressure of the refrigerant flowing into the gas-liquid separator 104 can be reduced.

  The effect of the control based on the flowchart of FIG. 3 will be described using the Mollier diagram of FIG. Before performing this control in the start-up operation, the refrigerant state in the refrigeration cycle apparatus 100 changes in the order of A, B, C, D, E, F, G, H, and A in FIG. On the other hand, after the control based on the flowchart of FIG. 3, the pressure of the refrigerant flowing into the gas-liquid separator 104 decreases. That is, the state of the refrigerant in the refrigeration cycle apparatus 100 changes in the order of A, B ′, C ′, D ′, E, F ′, G ′, H ′, and A.

  As shown in FIG. 4, the state (state F ′) of the refrigerant flowing into the gas-liquid separator 104 after performing the above control is compared with the state (state F) before performing the above control. Is low. As shown in FIG. 5, under the situation assumed in the present embodiment, when the pressure of the refrigerant flowing into the gas-liquid separator 104 decreases, the flow rate of the gas-phase refrigerant injected into the compressor 101 increases ( The operating point moves from point X to point Y in FIG. 5). That is, the liquid phase component of the refrigerant in the state F ′ is less than the liquid phase component of the refrigerant in the state F. In a transition period such as during start-up operation, the gas-liquid separator 104 does not completely separate the gas-phase refrigerant and the liquid-phase refrigerant, and a phenomenon occurs in which the liquid-phase refrigerant is likely to be mixed into the gas-phase refrigerant. If the liquid-phase refrigerant flowing into the gas-liquid separator 104 is reduced, this phenomenon is reduced. Therefore, in the present embodiment, the amount of the liquid phase component in the refrigerant injected based on Ti1 is suppressed to an acceptable level. Thereby, liquid compression is suppressed.

  In the present embodiment, control is performed based on the refrigerant temperature Ti in the injection passage 170, but control can also be performed based on other values. For example, based on the temperature of the refrigerant in the refrigerant circuit 160 between the first throttle device and the gas-liquid separator 104 or between the gas-liquid separator 104 and the second throttle device or in the gas-liquid separator 104, the first You may control the opening degree of this diaphragm | throttle device, and the opening degree of a 2nd diaphragm | throttle device.

  Further, a pressure sensor is used instead of the temperature sensor to detect the pressure of the refrigerant existing in the injection path 170 or in the refrigerant circuit 160 on the downstream side of the first throttle device and on the upstream side of the second throttle device. Based on this value, the opening degree of the first throttling device and the opening degree of the second throttling device can also be controlled.

  In the present embodiment, both the opening degree of the first throttling device and the opening degree of the second throttling device are controlled. Thereby, the fluctuation | variation of the pressure difference between the pressure of the high voltage | pressure side of a refrigerating cycle and the pressure of a low voltage | pressure side can be suppressed. Further, when both the opening degree of the first throttle device and the opening degree of the second throttle device are controlled, the dryness of the refrigerant flowing into the compressor 101 via the evaporator can be adjusted to an appropriate value. it can. In this way, the heating capacity of the refrigeration cycle apparatus 100 can be improved. However, the control device 108 may keep only the opening of the first throttling device gradually smaller while keeping the opening of the second throttling device constant. Even in this way, liquid compression can be suppressed.

  Further, the four-way valve (switching device) 120 may be omitted. Thereby, the configuration is simplified, and an advantageous configuration can be obtained from the viewpoint of maintenance and cost. Further, when the four-way valve 120 is omitted and the refrigerant flow direction is made constant as in the refrigeration cycle apparatus that constitutes the hot water supply apparatus or the like, the second throttle device may be a fixed throttle. This further simplifies the configuration.

  In the present embodiment, no injection throttle device is provided in the injection path 170. Thereby, an advantageous configuration is obtained from the viewpoint of cost. However, even if an injection throttle device is provided (for an emergency or the like), the above-described control may be performed with the injection throttle device open.

(Embodiment 2)
FIG. 6 shows a refrigeration cycle apparatus 200 according to Embodiment 2 of the present invention. The refrigeration cycle apparatus 200 of the present embodiment has a temperature sensor 131 (corresponding to the condenser temperature sensor in the claims) capable of measuring the temperature of the refrigerant flowing in the indoor heat exchanger 102 that functions as a condenser during heating operation. Is different from the refrigeration cycle apparatus 100 of the first embodiment. Other than the above, there is no difference, and the operation of the refrigeration cycle apparatus 200 of the present embodiment is the same as the operation of the refrigeration cycle apparatus 100 of the first embodiment except for the control described below. In the refrigeration cycle apparatus 200 shown in FIG. 6, the indoor side expansion device 103 and the outdoor side expansion device 105 are controlled as follows during the heating operation, but the same as in the present embodiment during the cooling operation of the refrigeration cycle apparatus. In order to implement this control, the temperature sensor 131 is provided in the outdoor heat exchanger 106, and the roles of the indoor expansion device 103 and the outdoor expansion device 105 may be reversed.

  In the present embodiment, control device 108 determines whether or not to end the start-up operation based on time change rate ΔTc of temperature Tc of the refrigerant flowing in the condenser.

  Control of the opening degree of the indoor side expansion device 103 (first expansion device) and the outdoor side expansion device 105 (second expansion device) performed by the control device 108 will be described with reference to the flowchart shown in FIG.

  The flowchart shown in FIG. 7 is obtained by replacing step S201 in the flowchart shown in FIG. 3 with steps S401 to S403.

  First, in step S401, the temperature sensor 131 detects the temperature Tc of the refrigerant flowing in the condenser, and the process proceeds to step S402. Tc is stored in the control device 108 each time.

  In step S402, the time change rate ΔTc of the temperature of the refrigerant flowing in the condenser is calculated from the detected temperature Tc, the temperature Tc ′ detected one time step stored in the control device 108, and the time step Δt.

  In step S403, the magnitude relationship between the calculated temperature change rate ΔTc and the threshold value ΔTc1 is determined. If the relationship ΔTc <ΔTc1 is established (YES in step S403), the process proceeds to step S202. If the relationship ΔTc <ΔTc1 is not satisfied (NO in step S403), the process proceeds to step S211.

  According to the control based on the flowchart of FIG. 7, the timing for proceeding to the transition operation (that is, the timing for ending the start-up operation) can be determined based on the state of the refrigerant flowing through the condenser. Thereby, it is possible to proceed to the transition operation at a more appropriate timing as compared with the control of the first embodiment.

(Embodiment 3)
FIG. 8 shows a refrigeration cycle apparatus 300 according to Embodiment 3 of the present invention. The refrigeration cycle apparatus 300 of the present embodiment has a temperature sensor 133 (corresponding to the evaporator temperature sensor in the claims) capable of measuring the temperature of the refrigerant flowing in the outdoor heat exchanger 106 that functions as an evaporator during heating operation. Is different from the refrigeration cycle apparatus 100 of the first embodiment. There is no difference except for the above, and the operation of the refrigeration cycle apparatus 300 of the present embodiment is the same as the operation of the refrigeration cycle apparatus 100 of the first embodiment except for the following control. In the refrigeration cycle apparatus 300 shown in FIG. 8, the indoor side expansion device 103 and the outdoor side expansion device 105 are controlled as follows during the heating operation, but the same as in the present embodiment during the cooling operation of the refrigeration cycle apparatus. In order to perform this control, the temperature sensor 133 may be provided in the indoor heat exchanger 102, and the roles of the indoor expansion device 103 and the outdoor expansion device 105 may be reversed.

  In the present embodiment, the control device 108 determines whether or not to end the start-up operation based on the time change rate ΔTe of the temperature Te of the refrigerant flowing in the evaporator.

  The control of the opening degree of the indoor expansion device 103 (first expansion device) and the opening amount of the outdoor expansion device 105 (second expansion device) performed by the control device 108 will be described with reference to the flowchart shown in FIG. To do.

  The flowchart shown in FIG. 9 is obtained by replacing step S201 in the flowchart shown in FIG. 3 with steps S501 to S503.

  First, in step S501, the temperature sensor 133 detects the temperature Te of the refrigerant flowing in the evaporator, and the process proceeds to step S502. Te is stored in the control device 108 each time.

  In step S502, the time change rate ΔTe of the temperature of the refrigerant flowing in the condenser is calculated from the detected temperature Te, the temperature Te ′ detected one time step stored in the control device 108, and the time step Δt.

  In step S503, the magnitude relationship between the calculated temperature change rate ΔTe and the threshold value ΔTe1 is determined. If the relationship of ΔTe <ΔTe1 is established (YES in step S503), the process proceeds to step S202. If the relationship ΔTe <ΔTe1 is not satisfied (NO in step S503), the process proceeds to step S211.

  According to the control based on the flowchart of FIG. 9, the timing for proceeding to the transition operation (that is, the timing for ending the start-up operation) can be determined based on the state of the refrigerant flowing through the evaporator. Thereby, it is possible to proceed to the transition operation at a more appropriate timing as compared with the control of the first embodiment.

(Other embodiments)
The control described in the above embodiment is for preventing liquid compression during start-up operation, but can also be applied to prevent liquid compression during other operations.

  For example, during the defrost operation, the liquid-phase refrigerant is easily injected into the compressor 101. Further, also during the stop operation, the suction temperature of the compressor 101 decreases, the liquid phase component of the refrigerant increases, and liquid compression is likely to occur. Also during these operations, liquid compression can be suppressed with the same configuration as the refrigeration cycle apparatus 100 of FIG.

  A flow chart for preventing liquid compression during the defrost operation is shown in FIG.

  For example, the control device 108 starts the defrost operation when the temperature of the outdoor heat exchanger 106 becomes equal to or lower than a predetermined temperature (for example, −5 ° C.).

  First, in step S601, the magnitude relationship between the time T elapsed from the start of the defrost operation and the threshold T2 (for example, 10 minutes) is determined. If the relationship of T> T2 is established (YES in step S601), the process proceeds to step S602 to end the defrost operation. If the relationship of T> T2 is not established (NO in step S601), the process proceeds to step S611 and the defrost operation is continued. The time T that has elapsed since the start of operation can be measured by a timer 109 attached to the control device 108.

  In step S602, a transition operation is performed, and then the process proceeds to step S603 to perform a normal operation.

  In step S611, the temperature sensor 130 detects the refrigerant temperature Ti in the injection passage 170.

  Next, the magnitude relationship between the temperature Ti and a predetermined threshold value Ti1 is determined (step S612). If the relationship of Ti> Ti1 is established (YES in step S612), the opening degree of the first throttling device is decreased by ΔA1 and the opening degree of the second throttling device is increased by ΔA2 (step S613), and the process proceeds to step S601. Return. If the relationship of Ti> Ti1 is not satisfied (NO in step S612), the process returns to step S601.

  According to the control based on the flowchart of FIG. 10, the opening degree of the first throttling device can be reduced and the opening degree of the second throttling device can be increased based on the temperature of the refrigerant in the injection passage 170. Thereby, the pressure of the refrigerant | coolant which flows in into the gas-liquid separator 104 can be reduced in the case of a defrost driving | operation. That is, since the liquid phase component of the refrigerant passing through the injection path 170 can be reduced, liquid compression can be suppressed.

  In the flowchart of FIG. 10, the defrost operation is controlled to end after a predetermined time T2 from the start of the defrost operation. For example, when the temperature of the outdoor heat exchanger 106 exceeds a certain temperature. The defrost operation may be terminated.

  Next, FIG. 11 shows a flowchart for preventing liquid compression during the stop operation.

  First, in step S701, the magnitude relationship between the time T that has elapsed since the start of the stop operation and a threshold T3 (for example, 3 minutes) is determined. If the relationship of T> T3 is satisfied (YES in step S701), the process proceeds to step S702 and the operation is stopped. If the relationship of T> T3 is not satisfied (NO in step S701), the process proceeds to step S711 and the stop operation is continued. The time T that has elapsed since the start of operation can be measured by a timer 109 attached to the control device 108.

  In step S <b> 711, the temperature sensor 130 detects the refrigerant temperature Ti in the injection path 170.

  Next, the magnitude relationship between the temperature Ti and a predetermined threshold value Ti1 is determined (step S712). If the relationship of Ti> Ti1 is established (YES in step S712), the opening degree of the first throttling device is decreased by ΔA1, the opening degree of the second throttling device is increased by ΔA2 (step S713), and the process proceeds to step S701. Return. If the relationship of Ti> Ti1 is not satisfied (NO in step S712), the process returns to step S701.

  According to the control based on the flowchart of FIG. 11, it is possible to reduce the opening of the first expansion device and increase the opening of the second expansion device based on the temperature of the refrigerant in the injection path 170. Thereby, the pressure of the refrigerant flowing into the gas-liquid separator 104 can be reduced during the stop operation. That is, since the liquid phase component of the refrigerant passing through the injection path 170 can be reduced, liquid compression can be suppressed.

  Further, in both cases of the defrost operation and the stop operation, the control can be performed based on other values instead of performing the control based on the refrigerant temperature Ti in the injection path 170. For example, based on the temperature of the refrigerant in the refrigerant circuit 160 between the first throttle device and the gas-liquid separator 104 or between the gas-liquid separator 104 and the second throttle device or in the gas-liquid separator 104, the first You may control the opening degree of this diaphragm | throttle device, and the opening degree of a 2nd diaphragm | throttle device. That is, based on the temperature of the refrigerant existing in the refrigerant circuit 160 downstream of the first throttle device and upstream of the second throttle device or in the injection passage 107, the opening degree of the first throttle device and the first The opening degree of the expansion device 2 may be controlled.

  Further, a pressure sensor is used instead of the temperature sensor to detect the pressure of the refrigerant existing in the injection path 170 or in the refrigerant circuit 160 on the downstream side of the first throttle device and on the upstream side of the second throttle device. Based on this value, the opening degree of the first throttling device and the opening degree of the second throttling device can also be controlled.

Further, the control device 108 may keep only the opening degree of the first throttling device gradually while keeping the opening degree of the second throttling device constant. Further, the four-way valve (switching device) 120 may be omitted, the four-way valve 120 may be omitted, and the second throttle device may be a fixed throttle.
(Control during normal operation)

  If the refrigeration cycle apparatus is controlled as described above, it is possible to perform an operation in which liquid compression is unlikely to occur while exhibiting the effect of injection during start-up operation, defrost operation, and stop operation. The refrigeration cycle apparatus is preferably operated as described in the following first normal operation to fourth normal operation during normal operation. According to this, it is possible to suppress an abnormal increase in the pressure of the refrigerant on the high pressure side in the refrigeration cycle during normal operation, and to obtain the effect of improving the heating capacity by injection while preventing the injection of liquid refrigerant to the compressor. it can.

(First normal operation)
The first normal operation will be described with reference to the refrigeration cycle apparatus 150 (FIG. 12) capable of performing the first normal operation.

  Also in the refrigeration cycle apparatus 150, a chlorofluorocarbon refrigerant is used as the refrigerant. However, the effect of the first normal operation is exhibited even when a refrigerant such as carbon dioxide that becomes a supercritical state after being compressed by the compressor 101 is used as the refrigerant. Therefore, in the following, the term radiator is used instead of the term condenser.

  The state of the refrigerant flowing through the refrigerant circuit 160 and the injection path 170 in the refrigeration cycle apparatus 150 during the first normal operation will be described with reference to the Mollier diagram of FIG. Hereinafter, the indoor heat exchanger 102 during the heating operation or the outdoor heat exchanger 106 during the cooling operation will be described as a radiator, and the indoor heat exchanger 102 during the cooling operation or the outdoor heat exchanger 106 during the heating operation will be described as an evaporator. To do. Further, the indoor side expansion device 103 during the heating operation or the outdoor side expansion device 105 during the cooling operation (that is, the expansion device upstream of the gas-liquid separator 104) is used as the first expansion device, and the indoor side during the cooling operation. The expansion device 103 or the outdoor expansion device 105 during heating operation (that is, the expansion device downstream of the gas-liquid separator 104) will be described as a second expansion device. This is the same in the second normal operation to the fourth normal operation described later.

  The low-pressure refrigerant (state O) sucked into the compressor 101 is compressed to an intermediate pressure (state P), merges with the refrigerant supplied from the injection path 170 (state Q), and then further compressed to a high temperature. High pressure (state R). The high-temperature and high-pressure refrigerant discharged from the compressor 101 flows into the radiator, where it is cooled and dissipated (state S). The high-pressure refrigerant that has flowed out of the radiator is expanded by the first throttling device to an intermediate pressure (state T). This refrigerant is separated in the gas-liquid separator 104 into a gas phase refrigerant and a liquid phase refrigerant (state U). The gas phase refrigerant flows into the injection path 170. The liquid phase refrigerant flows into the second expansion device. The liquid-phase refrigerant that has flowed into the second expansion device further expands to become a low-pressure refrigerant (state V). Thereafter, the low-pressure refrigerant evaporates in the evaporator to become a gaseous state (state O), then passes through the four-way valve 120 and is sucked into the compressor 101 again. The gas-phase refrigerant separated in the gas-liquid separator 104 passes through the injection path 170 and is sucked into the compressor 101 during the compression process.

  During the first normal operation, the control device 108 controls the rotational speed of the compressor 102 according to, for example, a load requested by the user, and the pressure of the refrigerant flowing into the gas-liquid separator 104 is a predetermined pressure stored in advance. The opening degree of the 1st expansion device and the 2nd expansion device is adjusted so that it may become.

  By the way, during the first normal operation, the pressure of the refrigerant on the high-pressure side of the refrigeration cycle (FIG. 13) due to some factor (for example, when the outside air temperature rises or when the blower fan of the radiator stops due to malfunction) during the normal operation. The pressure shown in the state R and the state S) may become too high. In such a case, the control device 108 shifts from the steady operation to the high pressure side abnormality elimination operation so that the pressure on the high pressure side of the refrigeration cycle is reduced, but the refrigerant flowing into the gas-liquid separator 104 ( The opening degree of the first throttling device and the second throttling device is adjusted so that the pressure in the state T) is kept below the saturated vapor pressure (the pressure at the intersection of the line segment ST and the saturated liquid line in FIG. 13). To do.

  In the first normal operation, the control device 108 is based on the detected value of the temperature sensor 131 (high pressure side detection means) that can measure the temperature of the refrigerant flowing in the indoor heat exchanger 102 that functions as a radiator during the heating operation. The opening degree of the inner expansion device 103 and the opening degree of the outdoor expansion device 105 are controlled. This control may be performed while the output of the compressor 101 is kept constant, or may be performed while the output of the compressor 101 is changed. Further, the control may be performed in parallel with the control of other devices. In the refrigeration cycle apparatus 150 shown in FIG. 12, the indoor side expansion device 103 and the outdoor side expansion device 105 are controlled as follows during the heating operation. In order to perform the same control as the first normal operation during the cooling operation of the refrigeration cycle apparatus, the temperature sensor 131 is provided in the outdoor heat exchanger 106, and the roles of the indoor expansion device 103 and the outdoor expansion device 105 are provided. Just reverse it.

  Hereinafter, the control of the opening degree of the indoor side expansion device 103 (first expansion device) and the outdoor side expansion device 105 (second expansion device) performed by the control device 108 will be described with reference to the flowchart shown in FIG. .

  First, in step S261, the temperature sensor 131 detects the temperature Th of the refrigerant flowing in the radiator.

  Next, the control device 108 determines the magnitude relationship between the temperature Th detected in Step S261 and a predetermined threshold Th1 (for example, 55 ° C.) (Step S262). If the relationship of Th> Th1 is established (YES in step S262), the process proceeds to step S263 to shift from steady operation to high pressure side abnormality elimination operation. If the relationship Th> Th1 is not satisfied (NO in step S262), the process returns to step S261. That is, in the first normal operation, whether to shift to the high-pressure side abnormality elimination operation is determined by comparing the magnitudes of Th and Th1. Steps S261 and S262 are a steady operation flow.

  In step S263 (main process), the control device 108 increases the opening degree of the first throttling device by ΔA3 and increases the opening amount of the second throttling device by ΔA4, and then proceeds to step S264. Here, ΔA3 and ΔA4 are set to values such that the pressure of the refrigerant in the gas-liquid separator 104 does not increase even if step S263 is performed. Such ΔA3 and ΔA4 can be determined by experiments conducted in advance.

  In step S264, the temperature sensor 131 again detects the temperature Th of the refrigerant flowing in the radiator. In step S265, the magnitude relationship between the temperature Th detected in step S264 and a predetermined threshold Th1 is determined. If the relationship Th> Th1 is established (YES in step S265), the process returns to step S263, and the high-pressure side abnormality elimination operation is continued. If the relationship Th> Th1 is not satisfied (NO in step S265), the process returns to step S261 (returns to the steady operation), and the high-pressure side abnormality elimination operation is terminated. That is, in the first normal operation, whether to end the high-pressure side abnormality elimination operation is determined by comparing the magnitudes of Th and Th1.

  As described above, in the first normal operation, the temperature Th of the refrigerant flowing in the radiator during the steady operation is monitored, and if the relationship of Th> Th1 is established, the operation proceeds to the high-pressure side abnormality elimination operation, and thereafter Th> The opening degree of the first throttling device is gradually increased and the opening degree of the second throttling device is gradually increased until the relationship of Th1 is not established.

  According to the control based on the flowchart of FIG. 14, it is possible to increase the opening of the first expansion device and increase the opening of the second expansion device based on the temperature Th of the refrigerant flowing in the radiator. it can. Thereby, the excessive raise of the temperature Th of the refrigerant | coolant which flows through the inside of a heat radiator can be suppressed.

  The effect of the control based on the flowchart of FIG. 14 will be described using the Mollier diagram of FIG. Before performing this control, the state of the refrigerant in the refrigeration cycle apparatus 150 changes in the order of O, P, Q, R, S, T, U, V, and O in FIG. On the other hand, after performing this control, the refrigerant state in the refrigeration cycle apparatus 150 changes in the order of O ′, P, Q, R ′, S ′, T, U, V ′, and O ′.

  When the pressure of the refrigerant on the high pressure side of the refrigeration cycle becomes too high, it can be considered to increase only the opening of the expansion device on the upstream side of the gas-liquid separator. If the measure is taken in this way, the pressure of the refrigerant on the high pressure side can be reduced. However, if it copes in this way, the pressure of the refrigerant | coolant in a gas-liquid separator will rise. When the refrigerant pressure in the gas-liquid separator exceeds the saturated vapor pressure, the liquid refrigerant is injected into the compressor.

  By the way, as described in, for example, Japanese Patent Application Laid-Open No. 2009-180427, if an on-off valve is provided in the injection passage 170, the on-off valve is closed to prevent liquid refrigerant from being injected into the compressor. Can do. However, if it does in this way, the effect of the heating capability improvement by injection cannot be acquired.

  In contrast, according to this control, when the pressure on the high-pressure side of the refrigeration cycle exceeds a predetermined value, the pressure on the high-pressure side of the refrigeration cycle can be reduced. Further, in the first normal operation, since the opening degree of the first throttling device is increased and the opening degree of the second throttling device is increased, the refrigerant in the gas-liquid separator 104 (state T in FIG. 15). Can prevent an increase in pressure. That is, according to the control performed in the first normal operation, the pressure of the refrigerant in the gas-liquid separator 104 is reduced to the saturated vapor while the pressure (in other words, the temperature) of the high-pressure refrigerant flowing in the radiator is reduced to a predetermined value or less. It is possible to obtain the effect of improving the heating ability by injection while keeping the pressure below.

(Second normal operation)
FIG. 16 shows a refrigeration cycle apparatus 250 capable of performing the second normal operation. The refrigeration cycle apparatus 250 is different from the refrigeration cycle apparatus 150 in that a temperature sensor 132 (high pressure side detection means) capable of measuring the temperature Tcom of refrigerant discharged from the compressor 101 is provided instead of the temperature sensor 131. Different. Other than the above, there is no difference, and the operation of the refrigeration cycle apparatus 250 during the second normal operation is the same as the operation of the refrigeration cycle apparatus 150 during the first normal operation except for the following control.

  In the second normal operation, as in the first normal operation, when the refrigerant pressure on the high pressure side of the refrigeration cycle becomes too high, the pressure on the high pressure side of the refrigeration cycle decreases, but the gas-liquid separator 104 The high pressure side abnormality elimination operation is performed so that the pressure of the refrigerant flowing into the tank is kept below the saturated vapor pressure.

  In the high pressure side abnormality elimination operation in the second normal operation, the control device 108 controls the opening degree of the first throttling device and the opening degree of the second throttling device based on the temperature Tcom detected by the temperature sensor 132. . Hereinafter, the control of the opening degree of the indoor side expansion device 103 (first expansion device) and the outdoor side expansion device 105 (second expansion device) performed by the control device 108 (high pressure side abnormality elimination operation) is shown in FIG. This will be described with reference to a flowchart.

  First, in step S361, the temperature sensor 132 detects the temperature Tcom of the refrigerant discharged from the compressor 101.

  Next, the control device 108 determines the magnitude relationship between the temperature Tcom detected in step S361 and a predetermined threshold Tcom1 (for example, 120 ° C.) (step S362). If the relationship of Tcom> Tcom1 is established (YES in step S362), the process proceeds to step S363 and shifts from the steady operation to the high pressure side abnormality elimination operation. If the relationship of Tcom> Tcom1 is not established (NO in step S362), the process returns to step S361. That is, in the second normal operation, whether or not to shift to the high pressure side abnormality elimination operation is performed by comparing the magnitudes of Tcom and Tcom1.

  In step S363, the control device 108 increases the opening degree of the first throttling device by ΔA3 and increases the opening amount of the second throttling device by ΔA4, and then proceeds to step S364. Note that ΔA3 and ΔA4 are the same as those in the first normal operation. In step S364, the temperature sensor 132 detects the temperature Tcom of the refrigerant discharged from the compressor 101 again. In step S365, the magnitude relationship between the temperature Tcom detected in step S364 and a predetermined threshold value Tcom1 is determined. If the relationship of Tcom> Tcom1 is established (YES in step S365), the process returns to step S363, and the high pressure side abnormality elimination operation is continued. If the relationship of Tcom> Tcom1 is not satisfied (NO in step S365), the process returns to step S361 (returns to the steady operation), and the high pressure side abnormality elimination operation is terminated. That is, in the second normal operation, whether or not to end the high-pressure side abnormality elimination operation is performed by comparing the magnitudes of Tcom and Tcom1.

  As described above, in the second normal operation, the temperature Tcom of the refrigerant discharged from the compressor 101 is monitored during the steady operation, and if the relationship of Tcom> Tcom1 is established, the operation proceeds to the high-pressure side abnormality elimination operation, and thereafter Tcom> The opening degree of the first throttling device is gradually increased and the opening degree of the second throttling device is gradually increased until the relationship of Tcom1 is not established.

  According to the control based on the flowchart of FIG. 17, it is possible to increase the opening of the first expansion device and increase the opening of the second expansion device based on the temperature Tcom of the refrigerant discharged from the compressor 101. it can. As a result, the temperature Tcom of the refrigerant discharged from the compressor 101 can be reduced to a predetermined value or lower while keeping the pressure of the refrigerant in the gas-liquid separator 104 at or below the saturated vapor pressure.

  Whether or not to shift to the high-pressure side abnormality elimination operation based on the temperature Th of the refrigerant flowing in the radiator in the first normal operation and based on the temperature Tcom of the refrigerant discharged from the compressor 101 in the second normal operation. In addition, although it is determined whether or not the high-pressure side abnormality elimination operation is to be ended, it can also be determined based on other values. For example, the determination may be performed based on the temperature of the refrigerant between the radiator in the refrigerant circuit 160 and the first throttling device.

  Further, by using a pressure sensor instead of the temperature sensor, the pressure of the refrigerant existing downstream of the compressor 101 in the refrigerant circuit 160 and upstream of the first expansion device is detected, and based on this value. Determination may be performed.

  Further, both the temperature sensor 131 and the temperature sensor 132 may be used to refer to both the temperature Th of the refrigerant flowing in the radiator and the temperature Tcom of the refrigerant discharged from the compressor 101. For example, it is determined whether to shift to the high-pressure side abnormality elimination operation and whether to end the high-pressure side abnormality elimination operation depending on whether any of the relationship of Th> Th1 and the relationship of Tcom> Tcom1 is established. You may go. In this way, safer operation is possible compared to the first normal operation and the second normal operation.

  Further, in the first normal operation and the second normal operation, when the refrigeration cycle apparatus 150 and the refrigeration cycle apparatus 250 are used for applications other than the air conditioner, the four-way valve (switching apparatus) 120 may be omitted. Thereby, the configuration is simplified, and an advantageous configuration can be obtained from the viewpoint of maintenance and cost.

(Third normal operation)
FIG. 18 shows a refrigeration cycle apparatus 350 capable of performing the third normal operation. The refrigeration cycle apparatus 350 functions as an evaporator during heating operation in addition to a temperature sensor 131 (high pressure side detection means) capable of measuring the temperature Th of the refrigerant flowing in the indoor heat exchanger 102 that functions as a radiator during heating operation. This is different from the refrigeration cycle apparatus 150 in that a temperature sensor 133 (low pressure side detection means) capable of measuring the temperature Te of the refrigerant flowing in the outdoor heat exchanger 106 which is a heat exchanger is provided. Other than the above, there is no difference, and the operation of the refrigeration cycle apparatus 350 during the third normal operation is the same as the operation of the refrigeration cycle apparatus 150 during the first normal operation except for the following control. In the refrigeration cycle apparatus 350 shown in FIG. 18, the indoor side expansion device 103 and the outdoor side expansion device 105 are controlled as follows during the heating operation. In order to perform the same control as the third normal operation during the cooling operation of the refrigeration cycle apparatus, the role of the temperature sensor 131, the role of the temperature sensor 133, the role of the indoor side expansion device 103, and the role of the outdoor side expansion device 105 Can be reversed.

  Even in the third normal operation, as in the first normal operation and the second normal operation, when the pressure of the refrigerant on the high pressure side of the refrigeration cycle becomes too high, the pressure on the high pressure side of the refrigeration cycle is decreased, The high pressure side abnormality elimination operation is performed so that the pressure of the refrigerant flowing into the gas-liquid separator 104 is kept below the saturated vapor pressure. In the high pressure side abnormality elimination operation in the third normal operation, the control device 108 determines the opening degree of the indoor expansion device 103 (first expansion device) and the opening amount of the outdoor expansion device 105 (second expansion device). Control is performed based on the temperature Th detected by the temperature sensor 131.

  By the way, if the pressure (in other words, temperature) of the refrigerant flowing in the evaporator is excessively reduced, the evaporator performance may not be sufficiently exhibited due to frost formation on the evaporator. Therefore, in the third normal operation, even if it is determined not to perform the high pressure side abnormality elimination operation, if it is determined that the pressure of the refrigerant flowing in the evaporator is lower than the predetermined value, The low-pressure side abnormality elimination operation is performed to increase the pressure of the refrigerant flowing through. In the low pressure side abnormality elimination operation in the third normal operation, the control device 108 controls the opening degree of the second expansion device based on the temperature Te detected by the temperature sensor 133.

  Hereinafter, the high pressure side abnormality elimination operation and the low pressure side abnormality elimination operation performed by the control device 108 will be described with reference to the flowchart shown in FIG. Note that the high pressure side abnormality elimination operation in the third normal operation is the same as the high pressure side abnormality elimination operation in the first normal operation, so the steps for realizing it are given the same reference numerals as in FIG. To do.

  If the relationship of Th> Th1 is not established in step S262 (NO in step S262), the process proceeds to step S471.

  In step S471, the temperature sensor 133 detects the temperature Te of the refrigerant flowing in the evaporator.

  Next, in step S472, the magnitude relationship between the temperature Te and a predetermined threshold Te2 (for example, 5 ° C.) is determined. If the relationship of Te <Te2 is established (YES in step S472), the process proceeds to step S473, and the operation proceeds to the low-pressure side abnormality elimination operation. If the relationship of Te <Te2 is not established (NO in step S472), the process returns to step S261. Thus, in the third normal operation, whether or not to shift to the low pressure side abnormality elimination operation is performed by comparing the magnitudes of Te and Te2.

  In step S473, the control device 108 increases the opening degree of the second throttling device by ΔA5, and proceeds to step S474. Here, ΔA5 can be an arbitrary value. In step S474, the temperature sensor 133 again detects the temperature Te of the refrigerant flowing in the evaporator. In step S475, the magnitude relationship between the temperature Te detected in step S474 and a predetermined threshold Te2 is determined. If the relationship of Te <Te2 is established (YES in step S475), the process returns to step S473, and the low-pressure side abnormality elimination operation is continued. If the relationship of Te <Te2 is not satisfied (NO in step S475), the process returns to step S261 (returns to the steady operation), and the low pressure side abnormality elimination operation is terminated. That is, in the third normal operation, whether or not to end the low-pressure side abnormality elimination operation is performed by comparing the magnitudes of Te and Te2.

  According to the control based on the flowchart of FIG. 19, even if it is determined that the high pressure side abnormality elimination operation is not performed, the low pressure side abnormality elimination operation is used to suppress an excessive decrease in the temperature Te of the refrigerant flowing in the evaporator. can do.

  In the third normal operation, it is determined whether to shift to the high pressure side abnormality elimination operation and whether to end the high pressure side abnormality elimination operation based on the temperature Th of the refrigerant flowing in the radiator. The determination may be made based on the temperature of the refrigerant discharged from the compressor 101 as in the second normal operation.

  Further, in the third normal operation, it is determined whether or not the low pressure side abnormality elimination operation is performed based on the temperature Te of the refrigerant flowing in the evaporator, but it can also be determined based on other values. For example, the temperature of the refrigerant sucked into the compressor 101 may be measured by a temperature sensor, the detected temperature may be compared with another threshold value, and determination may be made based on this. That is, the temperature sensor may be provided at any position as long as it is downstream of the second expansion device and upstream of the compressor 101 where the refrigerant has a low pressure.

  Further, by using a pressure sensor instead of the temperature sensor, the pressure of the refrigerant existing downstream of the second expansion device in the refrigerant circuit 160 and upstream of the compressor 101 is detected, and based on this value. It is also possible to determine whether or not to perform the low pressure side abnormality elimination operation.

(4th normal operation)
FIG. 20 shows a refrigeration cycle apparatus 450 capable of performing the fourth normal operation. The refrigeration cycle apparatus 450 measures the pressure of the refrigerant in the gas-liquid separator 104 in addition to the temperature sensor 131 that can measure the temperature Th of the refrigerant flowing in the indoor heat exchanger 102 that functions as a radiator during heating operation. The refrigeration cycle apparatus 150 is different from the refrigeration cycle apparatus 150 in that a pressure sensor 140 (intermediate pressure side pressure sensor) and a temperature sensor 134 (radiator outlet temperature sensor) for detecting the temperature of the refrigerant flowing out of the indoor heat exchanger 102 are provided. There is no difference except for the above, and the operation of the refrigeration cycle apparatus 450 during the fourth normal operation is the same as the operation of the refrigeration cycle apparatus 150 during the first normal operation except for the following control. In the refrigeration cycle apparatus 450 shown in FIG. 20, the indoor side expansion device 103 and the outdoor side expansion device 105 are controlled as follows during the heating operation. In order to perform the same control as the fourth normal operation during the cooling operation of the refrigeration cycle apparatus, the temperature sensor 131 is connected to the outdoor heat exchanger 106, and the temperature sensor 134 is connected to the outdoor expansion device 105 and the outdoor heat exchanger 106. They may be provided respectively, and the roles of the indoor expansion device 103 and the outdoor expansion device 105 may be reversed.

  Even in the fourth normal operation, as in the first normal operation to the third normal operation, when the pressure of the refrigerant on the high pressure side of the refrigeration cycle becomes too high, the pressure on the high pressure side of the refrigeration cycle is decreased, The high pressure side abnormality elimination operation is performed so that the pressure of the refrigerant flowing into the gas-liquid separator 104 is kept below the saturated vapor pressure. In the high pressure side abnormality elimination operation in the fourth normal operation, the control device 108 determines the opening degree of the first throttling device and the second throttling device by the temperature Th detected by the temperature sensor 131 and the temperature sensor 134. Control is performed based on the detected temperature Tec and the pressure Pi detected by the pressure sensor 140.

  Hereinafter, the control of the opening degree of the indoor expansion device 103 (first expansion device) and the outdoor expansion device 105 (second expansion device) performed by the control device 108 (high-pressure side abnormality elimination operation) is shown in FIG. This will be described with reference to a flowchart.

  The flowchart shown in FIG. 21 is obtained by adding steps S564 to S568 between steps S263 and S264 of the flowchart shown in FIG. Below, a different part from the flowchart of FIG. 14 is demonstrated.

  In the fourth normal operation, in step S263, the opening degree of the first throttling device is increased by ΔA3 and the opening degree of the second throttling device is increased by ΔA4, and the process proceeds to step S564. In the fourth normal operation, the values of ΔA3 and ΔA4 can be set to arbitrary values.

  In step S564, the temperature Tec of the refrigerant flowing out of the radiator is detected by the temperature sensor 134, and the process proceeds to step S565.

  In step S565, the saturated vapor pressure Pi6 is determined from the temperature Th detected in step S261 and the temperature Tec detected in step S564. When determining the saturated vapor pressure Pi6, a table or the like can be used.

  Next, in step S566, the pressure sensor 140 detects the refrigerant pressure Pi in the gas-liquid separator 104, and the process proceeds to step S567.

  In step S567, the control device 108 determines the magnitude relationship between the pressure Pi and the saturated vapor pressure Pi6. If the relationship of Pi> Pi6 is established (YES in step S567), the process proceeds to step S568, the opening of the first throttling device is decreased by ΔA6, the opening of the second throttling device is increased by ΔA7, and step S264 is performed. Proceed to If the relationship Pi> Pi6 is not satisfied (NO in step S567), the process proceeds to step S264. Since ΔA6 is smaller than ΔA3, the pressure of the refrigerant flowing through the radiator (that is, the high-pressure side) decreases even when both the control in step S263 and step S568 is performed.

  According to the control based on the flowchart of FIG. 21, the pressure of the high-pressure refrigerant flowing in the radiator can be reduced to a predetermined value or less.

  Furthermore, according to this control, the pressure of the refrigerant in the gas-liquid separator 104 can be monitored and lowered as necessary. Thereby, compared with the refrigeration cycle apparatus of 1st normal operation-3rd normal operation, in the 4th normal operation, the pressure of the refrigerant | coolant in the gas-liquid separator 104 can be more reliably made into a saturated vapor pressure or less.

  In the first normal operation to the third normal operation, the pressure of the refrigerant flowing into the gas-liquid separator 104 must be surely made equal to or lower than the saturated vapor pressure only by step S263 (or step S363). Therefore, it is preferable that the amount of change ΔA4 of the opening degree of the second expansion device is made somewhat larger than the amount of change ΔA4 determined by experiments or the like. That is, the pressure of the refrigerant flowing into the gas-liquid separator 104 may be unnecessarily low. On the other hand, in the fourth normal operation, the pressure of the refrigerant flowing into the gas-liquid separator 104 can be reliably kept below the saturated vapor pressure through steps S564 to S568. Therefore, the amount of change ΔA4 in step S263 can be made smaller than in the first normal operation to the third normal operation. As a result, the opening degree of the second expansion device can be controlled so that the pressure of the refrigerant flowing into the gas-liquid separator 104 is equal to or lower than the saturated vapor pressure and close to the saturated vapor pressure. A refrigeration cycle apparatus that can be operated in a simple manner can be configured.

  Further, instead of detecting the temperature Th of the refrigerant flowing in the radiator by the temperature sensor 131, the pressure of the refrigerant existing downstream of the compressor 101 in the refrigerant circuit 160 and upstream of the first expansion device is determined. It may be detected, and based on this value, it may be determined whether to shift to the high pressure side abnormality elimination operation and whether to end the high pressure side abnormality elimination operation. In this way, the saturated vapor pressure can also be determined from this value and the temperature Tec.

  In the fourth normal operation, the pressure Pi of the refrigerant in the gas-liquid separator 104 is directly detected by the pressure sensor 140 provided in the gas-liquid separator 104, but it is not always necessary to detect it directly. There is no. For example, gas-liquid separation is indirectly performed between the first throttle device and the gas-liquid separator 104 in the refrigerant circuit 160, between the gas-liquid separator 104 and the second throttle device, or from the pressure or temperature of the refrigerant in the injection path 170. The pressure Pi of the refrigerant in the vessel 104 may be determined.

  In the fourth normal operation, the saturated vapor pressure Pi6 is determined from the detected temperature Th and temperature Tec. However, for example, a value corresponding to the detected value of the temperature sensor 131 may be used as the saturated vapor pressure Pi6. As a result, the control performed by the control device 108 is simplified, and a useful configuration can be obtained from the viewpoint of computer resources.

  The above-described first normal operation to fourth normal operation can be summarized as follows.

  That is, a refrigeration cycle apparatus capable of performing normal operation includes a compressor that compresses a refrigerant, a radiator that radiates the refrigerant compressed by the compressor, a first throttle device that expands the refrigerant radiated by the radiator, A gas-liquid separator that separates the refrigerant expanded in the first expansion device into a gas-phase refrigerant and a liquid-phase refrigerant; a second expansion device that expands the liquid-phase refrigerant separated in the gas-liquid separator; and A refrigerant circuit including an evaporator for evaporating the refrigerant expanded by the second expansion device, an injection path for supplying the gas-phase refrigerant separated by the gas-liquid separator to the compressor during the compression process, and the refrigerant A high pressure side detecting means for detecting a temperature or pressure of a refrigerant existing downstream of the compressor in the circuit and upstream of the first throttle device; and a detection value of the high pressure side detecting means is a predetermined value. When exceeded By increasing the opening of the first throttle device and increasing the opening of the second throttle device, the high pressure of the refrigeration cycle is reduced while keeping the pressure of the refrigerant in the gas-liquid separator below the saturated vapor pressure. And a control device that performs the high-pressure side abnormality elimination operation to be performed.

  According to this configuration, when the pressure of the refrigerant on the high pressure side of the refrigeration cycle becomes too high, the opening of the first throttling device can be increased to reduce the pressure of the refrigerant on the high pressure side of the refrigeration cycle. Furthermore, according to the refrigeration cycle apparatus described above, not only the opening degree of the first expansion device is increased, but also the opening amount of the second expansion device is increased. When the opening degree of the second expansion device is increased, the pressure of the refrigerant in the gas-liquid separator decreases. That is, when the opening degree of the first throttling device is increased and the opening degree of the second throttling device is also increased, the pressure of the refrigerant in the gas-liquid separator is reduced while lowering the pressure of the refrigerant on the high pressure side of the refrigeration cycle. Can be suppressed and kept below the saturated vapor pressure. Therefore, an abnormal increase in pressure on the high-pressure side of the refrigeration cycle can be suppressed, and the refrigerant can be injected into the compressor while preventing the liquid refrigerant from being injected into the compressor.

  The refrigeration cycle apparatus further includes low-pressure side detection means for detecting the temperature or pressure of the refrigerant existing downstream of the second throttle device and upstream of the compressor in the refrigerant circuit, Even when the controller does not perform the high-pressure side abnormality elimination operation, when the detected value of the low-pressure side detection means is smaller than a predetermined value, the low-pressure side abnormality elimination that gradually increases the opening of the second throttle device It is preferable to operate.

  In the refrigeration cycle apparatus, the control device increases the opening of the first expansion device by a predetermined amount ΔA3 and performs the opening of the second expansion device during the high-pressure side abnormality elimination operation. It is preferable to repeat the main step of increasing the value by a predetermined amount ΔA4 until the detection value of the high-pressure side detection means falls below the predetermined value.

  In the refrigeration cycle apparatus, the high-pressure side detection means is a radiator temperature sensor that detects a temperature of the refrigerant flowing in the radiator, and a pressure sensor that detects a pressure of the refrigerant in the gas-liquid separator; A radiator outlet temperature sensor for detecting the temperature of the refrigerant flowing out of the radiator, and the control device includes a radiator temperature sensor and a radiator outlet temperature sensor each time the main process is executed. The saturated vapor pressure of the refrigerant flowing into the gas-liquid separator is calculated from the detected value, and whether or not the pressure detected by the pressure sensor exceeds the saturated vapor pressure is detected by the pressure sensor. When the pressure exceeds the saturated vapor pressure, the opening of the first throttle device is reduced within a range smaller than the predetermined amount ΔA3, and the opening of the second throttle device is further increased. It is preferable.

  The refrigeration cycle apparatus of the present invention can be used as a refrigeration cycle apparatus for various purposes such as for hot water supply and air conditioning.

In step S502, the time change rate ΔTe of the temperature of the refrigerant flowing in the evaporator is calculated from the detected temperature Te, the temperature Te ′ detected one time step stored in the control device 108, and the time step Δt.

Claims (8)

A compressor that compresses the refrigerant; a condenser that condenses the refrigerant compressed by the compressor; a first expansion device that expands the refrigerant condensed by the condenser; and a refrigerant expanded by the first expansion device A gas-liquid separator that separates the refrigerant into a liquid-phase refrigerant, a second expansion device that expands the liquid-phase refrigerant separated by the gas-liquid separator, and an evaporation that evaporates the refrigerant expanded by the second expansion device A refrigerant circuit including a circulator, wherein the refrigerant circuit circulates a refrigerant that does not enter a supercritical state after being compressed by the compressor;
An injection path for supplying the gas-phase refrigerant separated by the gas-liquid separator to the compressor during the compression process;
Detecting means for detecting the temperature or pressure of the refrigerant existing downstream of the first throttle device in the refrigerant circuit and upstream of the second throttle device or in the injection path;
When the detection means detects that the pressure of the refrigerant flowing into the gas-liquid separator exceeds a predetermined pressure lower than the saturated vapor pressure during the start-up operation, the defrost operation, or the stop operation, the first throttling A control device for reducing the opening of the device;
A refrigeration cycle apparatus comprising:   The control device, when the detection means detects that the pressure of the refrigerant flowing into the gas-liquid separator exceeds the predetermined pressure during the start-up operation, the defrost operation, or the stop operation. The refrigeration cycle apparatus according to claim 1, wherein the opening degree of the first throttling device is reduced and the opening degree of the second throttling device is increased. The detection means is a temperature sensor;
The control device compares the temperature Ti detected by the temperature sensor with the threshold value Ti1 during the start-up operation, defrost operation or stop operation, and if the relationship of Ti> Ti1 is established, The refrigeration cycle apparatus according to claim 1 or 2, wherein it is determined that the pressure of the refrigerant flowing in exceeds the predetermined pressure.   The control device detects the opening degree of the first expansion device when the detection means detects that the pressure of the refrigerant flowing into the gas-liquid separator exceeds the predetermined pressure at least during the start-up operation. The refrigeration cycle apparatus according to any one of claims 1 to 3, wherein the refrigeration cycle apparatus is reduced, or the opening degree of the first throttling device is reduced and the opening degree of the second throttling device is increased.   The refrigeration cycle apparatus according to claim 4, wherein the control device ends the start-up operation after a predetermined time has elapsed from the start of start-up.   A condenser temperature sensor for detecting the temperature of the refrigerant flowing in the condenser; and the control device compares a time change rate ΔTc calculated from the temperature detected by the condenser temperature sensor with a threshold value ΔTc1; The refrigeration cycle apparatus according to claim 4, wherein the start-up operation is terminated if a relationship of ΔTc> ΔTc1 is established.   An evaporator temperature sensor for detecting the temperature of the refrigerant flowing in the evaporator, and the control device compares a time change rate ΔTe calculated from the temperature detected by the evaporator temperature sensor with a threshold value ΔTe1; The refrigeration cycle apparatus according to claim 4, wherein the start-up operation is terminated when a relationship of ΔTe> ΔTe1 is established.   The refrigeration cycle apparatus according to any one of claims 1 to 7, further comprising a switching device capable of switching between heating operation and cooling operation.

Images