JP2005043008A - Refrigerating cycle device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To accurately determine a refrigerant shortage in a short time after starting a compressor in a hot gas heating mode. <P>SOLUTION: An accumulator 19 is installed between an outlet side of an indoor heat exchanger 18 and a suction side of the compressor 10, an electric heater 40 is provided for heating a liquid refrigerant in the accumulator 19 during the heating mode, and a temperature sensor 42 is provided for detecting a temperature of the accumulator 19. In a state wherein a liquid surface of the liquid refrigerant is substantially not formed in an accumulator 19 interior, the temperature of the accumulator 19 when the accumulator 19 is heated by the electric heater 40 is used as a determination temperature T1, and a refrigerant shortage is determined when a detected temperature of the temperature sensor 42 during heating of the electric heater 40 rises to the determination temperature T1 or higher. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a refrigeration cycle apparatus that accurately determines refrigerant shortage (leakage) during heating mode, and in particular, discharges refrigerant discharged from a compressor (hot gas) to the outdoor heat exchanger (condenser) side during heating mode. By bypassing it and introducing it directly into the indoor heat exchanger (evaporator), it is suitable for use in a vehicle refrigeration cycle apparatus in which the indoor heat exchanger acts as a radiator for the gas refrigerant.

  Conventionally, in a vehicle air conditioner, warm water (engine cooling water) is circulated to a heating heat exchanger during heating in winter, and the conditioned air is heated using the warm water as a heat source in the heating heat exchanger. In this case, when the hot water temperature is low, the temperature of the air blown into the passenger compartment may decrease and the required heating capacity may not be obtained.

  Thus, Patent Document 1 proposes a refrigeration cycle apparatus that can exhibit a hot gas heating function. In this conventional apparatus, when the hot water temperature is lower than a predetermined temperature just after the engine is started, the compressor discharge gas refrigerant (hot gas) is bypassed the outdoor heat exchanger (condenser) to the indoor heat exchanger (evaporator). By introducing and radiating heat from the gas refrigerant to the conditioned air with the indoor heat exchanger, the auxiliary heating function can be exhibited.

Furthermore, in the conventional apparatus of Patent Document 1, a means for determining whether or not the refrigerant is insufficient in the hot gas heating mode is also proposed. Specifically, as shown in FIG. 7, the boundary pressure P0 that divides the refrigerant shortage region and the refrigerant normal region is determined according to the outside air temperature for the high pressure during heating mode operation, and the high pressure is higher than the boundary pressure P0. It is determined that the refrigerant is insufficient when it is in the low region, that is, the refrigerant shortage region.
JP 2001-12830 A

  By the way, immediately after the start of the heating mode (compressor), it is a transition period in which the high pressure increases, and the fluctuation range of the high pressure is large. Therefore, in the case of determining the refrigerant shortage based on the high pressure during the heating mode operation as in the above prior art, the refrigerant is short until a predetermined time (for example, 30 seconds to 1 minute) elapses after the heating mode is started. Cannot be determined. Further, since the high pressure changes due to various factors even when the amount of refrigerant is normal, the amount of refrigerant that can determine whether the refrigerant is insufficient is significantly smaller than the normal amount of refrigerant.

  Therefore, according to the prior art, it is necessary to continue the operation of the compressor for about 30 seconds to 1 minute after the activation of the heating mode even in the extreme refrigerant shortage state. As a result, lubrication shortage due to refrigerant shortage is caused, which adversely affects the life of the compressor.

  The present invention has been made in view of the above points, and an object of the present invention is to make it possible to accurately determine the shortage of refrigerant in a short time after the start of the compressor in the heating mode.

  The present invention has devised technical means for achieving the above object based on the following experimental findings.

  In the present applicant, first, in Japanese Patent Application No. 2001-346197, a cooling refrigeration cycle in which an indoor heat exchanger is operated as an evaporator and a refrigerant discharged from the compressor are converted into an indoor heat exchanger by a hot gas bypass passage. In a refrigeration cycle apparatus configured to be able to switch between a hot gas heater cycle that directly operates and operates the indoor heat exchanger as a radiator, a refrigerant gas-liquid is provided between the outlet side of the indoor heat exchanger and the compressor suction side. An accumulator that separates the liquid refrigerant and stores the liquid refrigerant and leads the gas refrigerant to the compressor suction side is provided, and this accumulator is equipped with heating means such as an electric heater that heats the liquid refrigerant in the heating mode by the hot gas heater cycle Has proposed.

  According to this prior application, in the heating mode, the liquid refrigerant in the accumulator is heated by the heating means, thereby promoting the evaporation of the liquid refrigerant → the increase in the compressor suction pressure (the density of the suction refrigerant) → the increase in the compressor discharge pressure → The phenomenon of an increase in the work of compression → an increase in the amount of heat released from the indoor heat exchanger occurs, and the heating capacity of the hot gas heater cycle can be improved.

  By the way, when the amount of refrigerant in the hot gas heater cycle is insufficient in the heating mode by the hot gas heater cycle, the accumulator is filled with the gas refrigerant and the liquid refrigerant liquid level is not formed. Since the heat transfer coefficient for gas refrigerant is significantly lower than that of liquid refrigerant, when there is no refrigerant liquid level in the accumulator, the amount of heat transfer from the heating means to the refrigerant side in the accumulator is extremely reduced, and the heating means Is almost empty. As a result, the surface temperature of the accumulator rises sharply compared to when the refrigerant amount is normal (when the refrigerant liquid level is formed).

  In this way, when the amount of refrigerant in the hot gas heater cycle is insufficient in the heating mode in which the liquid refrigerant in the accumulator is heated by the heating means, the surface temperature of the accumulator is compared with the normal amount of refrigerant (when the refrigerant liquid level is formed). In the present invention, focusing on the phenomenon of sudden rise, the rise in the surface temperature of the accumulator is judged in the heating mode to judge the lack of refrigerant.

  That is, according to the first aspect of the present invention, the accumulator includes the heating means (40) for heating the liquid refrigerant in the heating mode and the temperature detection means (42) for detecting the temperature of the accumulator (19). ) The temperature of the accumulator (19) when the accumulator (19) is heated by the heating means (40) in a state where the liquid refrigerant liquid level is not substantially formed inside is set as the first determination temperature (T1), and the heating means ( When the temperature detected by the temperature detecting means (42) rises to the first determination temperature or higher during the heating in (40), the refrigerant shortage is determined.

  As described above, when the accumulator (19) is heated by the heating means (40) in a state where the liquid refrigerant liquid level is not substantially formed inside the accumulator (19), the heat to the gas refrigerant inside the accumulator (19). Since the amount of movement is extremely reduced and the air travels substantially, the surface temperature of the accumulator (19) rises rapidly due to the heating action of the heating means (40).

  Therefore, compared with the pressure determination method of the prior art, the shortage of refrigerant can be accurately determined in a short time after the heating mode is started (after the compressor is started) and with a larger amount of refrigerant.

  Therefore, as in claim 2, when the refrigerant shortage is determined, the compressor (10) is stopped, so that the protective effect of the compressor (10) can be enhanced. That is, when the refrigerant is insufficient, after the heating mode is started, the time during which the compressor (10) operates with insufficient lubrication can be shortened, and the protective effect of the compressor (10) can be enhanced.

In invention of Claim 3, in Claim 2, it sets refrigerant | coolant mode at the time of starting of heating mode, and performs the refrigerant | coolant collection | recovery driving | operation which collect | recovers the stagnation refrigerant | coolant by the side of an outdoor heat exchanger (14),
When the refrigerant shortage is determined, the refrigerant recovery operation is performed again a predetermined number of times, and the compressor (10) is stopped when the refrigerant shortage state is maintained even after the refrigerant recovery operation is re-executed.

  According to this, when there is a refrigerant shortage in the hot gas heater cycle due to the presence of the stagnant refrigerant on the outdoor heat exchanger (14) side, the refrigerant recovery operation is re-executed to re-execute the refrigerant in the hot gas heater cycle. In some cases, the refrigerant shortage can be resolved. In that case, it becomes unnecessary to stop the compressor (10) due to elimination of the refrigerant shortage, and the execution of the heating mode can be continued.

  When the refrigerant shortage state is maintained even after re-execution of the refrigerant recovery operation, the amount of refrigerant enclosed in the cycle is originally reduced. In this case, the compressor (10) is stopped and the compressor ( 10) can be reliably protected.

In invention of Claim 4, the heating mode which operates an indoor heat exchanger (18) as a heat radiator by introduce | transducing into the indoor heat exchanger (18) the refrigerant | coolant discharged from the compressor (10) is performed. In the refrigeration cycle apparatus
An accumulator (19) is installed on the suction side of the compressor (10) to separate the gas and liquid of the refrigerant and store the liquid refrigerant and lead the gas refrigerant to the suction side of the compressor (10).
The accumulator (19) includes a heating means (40) for heating the liquid refrigerant in the accumulator (19) and a temperature detection means (42) for detecting the temperature of the accumulator (19) in the heating mode,
The temperature of the accumulator (19) when the accumulator (19) is heated by the heating means (40) in a state where the liquid level of the liquid refrigerant is not substantially formed inside the accumulator (19) is defined as a first determination temperature (T1).
When the temperature detected by the temperature detecting means (42) rises to the first determination temperature (T1) or higher during heating by the heating means (40), the lack of refrigerant is determined.

  The invention according to claim 4 is a hot gas heater cycle (H) in which the refrigerant discharged from the compressor (10) is directly introduced into the indoor heat exchanger (18) by the hot gas bypass passage (20) in claim 1. Is not limited. That is, since the idea of the present invention can be implemented in a well-known heat pump type refrigeration cycle apparatus, the invention according to claim 4 does not limit the hot gas heater cycle (H).

  In the invention according to the fourth aspect, the same effect as that of the first aspect can be exhibited in the refrigerant shortage determination in the heating mode.

According to a fifth aspect of the present invention, in any one of the first to fourth aspects, at the time of heating by the heating means (40), when the accumulator (19) is fully filled with liquid refrigerant. The temperature of the accumulator (19) is set as the second determination temperature (T2),
If the temperature detected by the temperature detection means (42) is equal to or lower than the second determination temperature (T2) during heating by the heating means (40), the full state of the accumulator (19) is determined and the compressor (10) is stopped. It is characterized by that.

  According to this, since the compressor (10) can be automatically stopped when the accumulator (19) is full, liquid compression of the compressor (10) can be prevented in advance.

  According to a sixth aspect of the present invention, in any one of the first to fifth aspects, the heating means is an electric heater (40), and the physical quantity correlated with the outside air temperature is equal to or less than a predetermined value in the heating mode. In addition, the electric heater (40) is energized.

  According to this, it is possible to improve the heating capacity by automatically energizing the electric heater (40) at the low outside temperature in the heating mode.

  According to a seventh aspect of the present invention, in the sixth aspect, when the electric heater 40 is not energized in the heating mode, the refrigerant shortage is determined when the refrigerant pressure falls below a predetermined value.

  According to this, when the electric heater 40 is not energized, the refrigerant shortage can be determined based on the refrigerant pressure.

  In addition, the code | symbol in the bracket | parenthesis of each said means shows the correspondence with the specific means as described in embodiment mentioned later.

(First embodiment)
FIG. 1 illustrates the overall configuration of a vehicle air conditioner including a refrigeration cycle apparatus according to the first embodiment. The compressor 10 is driven by a water-cooled vehicle engine 12 via an electromagnetic clutch 11, and is composed of, for example, a fixed capacity swash plate compressor.

  The discharge side of the compressor 10 is connected to a condenser 14 via a cooling electromagnetic valve 13, and the outlet side of the condenser 14 is connected to a liquid receiver 15 that separates gas-liquid refrigerant and stores liquid refrigerant. . The condenser 14 is an outdoor heat exchanger that is arranged in the vehicle engine room together with the compressor 10 and the like and exchanges heat with the outside air (cooling air) blown by the electric cooling fan 14a.

  The outlet side of the liquid receiver 15 is connected to a temperature type expansion valve 16 constituting a cooling decompression device. The outlet side of the temperature type expansion valve 16 is connected to the inlet side of the evaporator 18 via a check valve 17. The outlet side of the evaporator 18 is connected to the suction side of the compressor 10 via an accumulator 19. The specific configuration of the accumulator 19 will be described later with reference to FIG.

  From the discharge side of the compressor 10 to the suction side of the compressor 10 through the cooling solenoid valve 13 → the condenser 14 → the liquid receiver 15 → the temperature type expansion valve 16 → the check valve 17 → the evaporator 18 → the accumulator 19. An ordinary cooling refrigeration cycle C is constituted by the returning closed circuit.

  As is well known, the temperature type expansion valve 16 adjusts the valve opening (refrigerant flow rate) so that the degree of superheat of the refrigerant at the outlet of the evaporator 18 is maintained at a predetermined value during normal refrigeration cycle operation (cooling mode). is there.

  On the other hand, a hot gas bypass passage 20 that bypasses the condenser 14 and the like is provided between the discharge side of the compressor 10 and the inlet side of the evaporator 18. The bypass passage 20 includes a heating electromagnetic valve 21 and a throttle. 21a is provided in series. The restrictor 21a forms a heating decompression device, and can be constituted by a fixed restrictor such as an orifice or a capillary tube. A heating hot gas heater cycle H is constituted by a closed circuit that returns from the discharge side of the compressor 10 to the suction side of the compressor 10 via the heating solenoid valve 21 → the throttle 21 a → the evaporator 18 → the accumulator 19.

  The air conditioning case 22 of the vehicle air conditioner constitutes an air passage through which air flows toward the passenger compartment. Air is blown through the air conditioning case 22 by an electric air conditioning blower 23. The air-conditioning blower 23 is shown as an axial flow type for simplification of illustration, but is actually a centrifugal blower having a centrifugal fan, and the air-conditioning blower 23 is controlled by a blower drive circuit. It is rotationally driven by. Note that the air flow rate of the blower 23 can be switched continuously or stepwise by adjusting the blower control voltage applied to the blower motor 23a.

  In addition, on the suction side of the air-conditioning blower 23, an outside air suction port 70 for sucking in outside air (air outside the vehicle compartment), an inside air suction port 71 for sucking in inside air (vehicle room air), and inside / outside air switching means are configured. A plate-shaped inside / outside air switching door 72 is provided. The inside / outside air switching door 72 is driven by an actuator such as a servo motor via a link mechanism (not shown), and at least an outside air mode for sucking outside air from the outside air suction port 70 and an inside air mode for sucking inside air from the inside air suction port 71 are at least. Switch.

  The evaporator 18 is an indoor heat exchanger installed in the air conditioning case 22, and in the cooling mode, the refrigerant circulates by the cooling refrigeration cycle C, and the air conditioner blower 23 by the refrigerant evaporation (heat absorption) in the evaporator 18. Since the blast air is cooled, it serves as a cooler. In the heating mode, since the high-temperature refrigerant gas (hot gas) from the hot gas bypass passage 20 radiates heat to the air in the evaporator 18, the evaporator 18 serves as a radiator.

  In the air conditioning case 22, a hot water heating heat exchanger 24 is installed on the air downstream side of the evaporator 18 to heat the blown air using hot water (engine cooling water) from the vehicle engine 12 as a heat source. The warm water circuit to the heating heat exchanger 24 is provided with a warm water valve 25 for controlling the warm water flow.

  By the way, the hot water heating heat exchanger 24 serves as a main heating means for heating the passenger compartment. On the other hand, an evaporator (indoor heat exchanger) forming a radiator by the hot gas heater cycle H is used. ) 18 constitutes auxiliary heating means.

  On the other hand, on the most air downstream side of the air conditioning case 22, a defroster (DEF) outlet 31 for blowing conditioned air (mainly hot air) toward the inner surface of the vehicle front window glass, and the face (upper body) of the vehicle occupant ) A face (FACE) outlet 32 for blowing out the conditioned air (mainly cold air) toward the vehicle and a foot (FOOT) for blowing out the conditioned air (mainly hot air) toward the feet (lower body) of the vehicle occupant ) A blowout port 33 is provided. Further, a plurality of mode switching doors 34 to 36 that selectively open and close these air outlets 31 to 33 are rotatably provided. The mode switching doors 34 to 36 constitute blowing mode switching means, and are driven by an actuator such as a servo motor via a link mechanism (not shown).

  The air-conditioning electronic control unit (hereinafter referred to as ECU) 26 is composed of a microcomputer and its peripheral circuits, performs predetermined arithmetic processing according to a preset program, opens and closes the electromagnetic valves 13 and 21, and other electrical devices ( 11, 14 a, 23, 25, an electric heater 40 described later, and the like).

  FIG. 2 illustrates a specific configuration of the accumulator 19. The accumulator 19 has a cylindrical tank body portion 19a formed of a metal such as aluminum, and an inlet disposed near the upper portion of the tank body portion 19a. The outlet refrigerant of the evaporator 18 flows into the tank main body 19a from the pipe 19b.

The gas-liquid of the inflowing refrigerant is separated by the density difference, the gas refrigerant collects on the upper side in the tank main body 19a, and the liquid refrigerant accumulates on the lower side in the tank main body 19a. In FIG. 2, line A is the liquid level of this liquid refrigerant. Then, a refrigerant outlet pipe 19c extending in the vertical direction is arranged inside the tank main body 19a, the upper end opening 19d of the refrigerant outlet pipe 19c is positioned near the ceiling of the tank main body 19a, and the lower part of the refrigerant outlet pipe 19c is Through the bottom of the tank main body 19a to be taken out and connected to the suction side of the compressor 10,
Gas refrigerant in the upper part of the tank main body 19a is sucked from the upper end opening 19d of the refrigerant outlet pipe 19c, and the tank main body from an oil return hole 19e opened in a portion of the refrigerant outlet pipe 19c near the bottom of the tank main body 19a. A small amount of liquid refrigerant in which oil is dissolved is sucked in the vicinity of the inner bottom portion of the portion 19a, and this liquid refrigerant is mixed into the gas refrigerant and led out to the suction side of the compressor 10.

  Further, the accumulator 19 is provided with an electric heater 40 as a heating means for heating the liquid refrigerant therein. The electric heater 40 is for improving the heating performance in the hot gas heating mode. Specifically, the electric heater 40 has a configuration in which a thin plate-like flexible electric resistor is covered with an elastic body such as silicon rubber. .

  Then, the electric heater 40 is arranged in a ring shape around the lower part of the outer peripheral surface of the cylindrical tank body 19a of the accumulator 19, and the ring-shaped holder member 41 is arranged on the outer circumference of the electric heater 40. To do. And the electric heater 40 can be clamped and fixed on the outer peripheral surface of the tank main-body part 19a by fastening between the both ends of the circumferential direction of the ring-shaped holder member 41 with a screw | thread. Further, a temperature sensor 42 serving as a temperature detecting means for detecting the surface temperature of the accumulator 19 is mounted on the outer peripheral surface of the tank body 19a.

  Since the surface temperatures of the tank main body 19a, the electric heater 40, and the holder member 41 are substantially equal due to heat conduction, the temperature sensor 42 may be disposed on the surface of the electric heater 40 or the holder member 41.

  FIG. 3 is an electric control block diagram of the first embodiment. The ECU 26 includes a water temperature sensor 27a of the vehicle engine 12, an outside air temperature sensor 27b, a blown air temperature sensor 27c of the evaporator 18, a compressor discharge pressure (cycle high pressure). ) Pressure sensor 27d, internal air temperature sensor 27e, and a solar radiation sensor 27f for detecting the amount of solar radiation in the passenger compartment. Further, the detection signal of the temperature sensor 42 of the accumulator 19 is also input to the ECU 26.

  In addition, the following operation switch group operation signals are input to the ECU 26 from the air conditioning operation panel 28 installed near the vehicle interior instrument panel. In other words, the air conditioner switch 29a commands to start or stop the compressor 10 of the refrigeration cycle, and serves as a cooling switch for setting the cooling mode. The hot gas switch 29b sets the heating mode by the hot gas heater cycle H and plays the role of a heating switch.

  Further, the air conditioning operation panel 28 includes a blow mode switching switch 29c for switching a blow mode of air conditioning, a temperature setting switch (temperature setting means) 29d for setting the temperature in the vehicle interior to a desired temperature, turning on and off the blower 23, and the air volume. A blower switch 29e for instructing switching and an inside / outside air switching switch 29f for instructing switching between the outside air mode and the inside air mode are provided.

  Next, the operation of this embodiment in the above configuration will be described. First, the operation of the refrigeration cycle will be described. When the air conditioner switch 29a is turned on and the cooling mode is set, the cooling electromagnetic valve 13 is opened by the ECU 26, and the heating electromagnetic valve 21 is closed. In addition, the electromagnetic clutch 11 is in a connected state, and the compressor 10 is driven by the vehicle engine 12.

  Therefore, the refrigerant discharged from the compressor 10 passes through the open cooling electromagnetic valve 13 and flows into the condenser 14. In the condenser 14, the refrigerant is cooled and condensed by the outside air blown by the cooling fan 14a. The refrigerant after passing through the condenser 14 is separated into gas and liquid by the liquid receiver 15, and only the liquid refrigerant is decompressed by the temperature type expansion valve 16 to be in a low-temperature and low-pressure gas-liquid two-phase state.

  Next, the low-pressure refrigerant passes through the check valve 17 and flows into the evaporator 18 to absorb heat from the conditioned air blown by the blower 23 and evaporate. The conditioned air cooled by the evaporator 18 is blown out from the face opening 32 or the like into the vehicle interior to cool the vehicle interior. The gas refrigerant evaporated in the evaporator 18 is sucked into the compressor 10 via the accumulator 19 and compressed.

  When the hot gas switch 29b is turned on in the winter and the heating mode by the hot gas heater cycle H is set, the cooling electromagnetic valve 13 is closed by the ECU 26, the heating electromagnetic valve 21 is opened, and the hot gas bypass is set. The passage 20 is opened. Further, the electromagnetic clutch 11 is connected by the ECU 26 and the compressor 10 is driven by the vehicle engine 12.

  For this reason, the high-temperature discharge gas refrigerant (superheated gas refrigerant) of the compressor 10 passes through the open heating electromagnetic valve 21 and is decompressed by the throttle 21a, and then flows into the evaporator 18. That is, the superheated gas refrigerant (hot gas) from the compressor 10 is directly introduced into the evaporator 18 by bypassing the condenser 14 and the like.

  At this time, the check valve 17 prevents the gas refrigerant from the hot gas bypass passage 20 from flowing to the temperature type expansion valve 16 side. Accordingly, the refrigeration cycle is operated in a closed circuit (hot gas heater cycle H) that returns to the discharge side of the compressor 10 → the heating solenoid valve 21 → the throttle 21 a → the evaporator 18 → the accumulator 19 → the suction side of the compressor 10. .

  And the superheated gas refrigerant | coolant after pressure-reducing by the aperture | diaphragm | squeezing 21a is thermally radiated to blowing air in the evaporator 18, and blowing air is heated. Here, the amount of heat released from the gas refrigerant in the evaporator 18 corresponds to the amount of compression work of the compressor 10. The gas refrigerant radiated by the evaporator 18 is sucked into the compressor 10 through the accumulator 19 and compressed.

  When the temperature of the hot water is low, such as immediately after the start of the engine 12 in cold weather, the air conditioner blower 23 is maintained in a stopped state, and after the hot water has risen to a predetermined temperature, the air conditioner blower 23 is started with a low air volume. It is controlled to warm up. By circulating the hot water of the vehicle engine 12 to the hot water heating heat exchanger 24 via the hot water valve 25, the blown air heated by the evaporator 18 can be further heated in the heat exchanger 24. Accordingly, even in cold weather, hot air having a higher temperature heated by both the evaporator 18 and the hot water heating heat exchanger 24 can be blown out into the passenger compartment.

  Incidentally, in the hot gas heater cycle H, an accumulator 19 is provided on the outlet side of the evaporator 18 in order to secure the refrigerant flow rate during hot gas heating and to secure the amount of oil returned to the compressor 10. Since the gas-liquid interface of the refrigerant is formed inside the accumulator 19, the refrigerant state on the low pressure side is balanced so that the refrigerant becomes a saturated gas on the outlet side of the evaporator 18.

  And since the electric heater 40 is attached over the whole periphery of the lower part of the outer peripheral surface of the accumulator 19, when the electric heater 40 is energized, the liquid refrigerant collected in the lower part in the accumulator 19 can be heated and evaporated. Here, since the electric heater 40 heats the liquid refrigerant instead of the gas refrigerant, the heat transfer rate is higher than that of the gas refrigerant. Accordingly, the amount of heat generated by the electric heater 40 can be efficiently transmitted to the refrigerant.

  Due to the evaporation of the liquid refrigerant in the accumulator 19, the pressure of the suction refrigerant of the compressor 10 rises and the density of the suction refrigerant of the compressor 10 rises, so that the weight flow rate discharged from the compressor 10 increases, The discharge pressure of the compressor 10 increases. Thereby, the compression work of the compressor 10 increases. As a result, the heat radiation amount in the evaporator 18 can be effectively increased, and the heating performance during hot gas heating can be effectively improved. That is, not only the amount of heat directly transferred to the refrigerant by the amount of heat generated by the electric heater 40 but also the amount of heat released by the increase in the compression work of the compressor 10 can be increased, and the heating performance during hot gas heating is effective. Can be improved.

  Next, the concept of refrigerant shortage determination in the heating mode according to the first embodiment will be described with reference to FIGS. 4 and 5. FIG. 4 shows the surface temperature of the accumulator 19 on the vertical axis and the heating mode on the horizontal axis. The elapsed time is taken. Changes in the surface temperature of the accumulator 19 when the liquid refrigerant in the accumulator 19 is heated by the electric heater 40 with an output capacity of 150 W under the condition of the outside air temperature = −10 ° C., and the amount of refrigerant in the hot gas heater cycle H is used as a parameter. Show.

  FIG. 5 shows the relationship between the refrigerant amount in the hot gas heater cycle H and the height of the refrigerant liquid level (A in FIG. 2) in the accumulator 19. Here, the coolant liquid level is the height h (see FIG. 2) from the bottom surface of the tank body 19a of the accumulator 19 to the coolant level.

  As shown in FIG. 5, the refrigerant liquid level starts to be formed when the refrigerant amount in the hot gas heater cycle H reaches 100 g, and the refrigerant liquid level increases as the refrigerant amount increases. Therefore, when the refrigerant amount is 100 g or less, the accumulator 19 is filled with the gas refrigerant. Since the heat transfer coefficient of the gas refrigerant is significantly smaller than that of the liquid refrigerant, the amount of heat transfer from the electric heater 40 to the gas refrigerant is small.

  For this reason, the electric heater 40 heats the accumulator 19 in an almost empty state, and the surface temperature of the accumulator 19 rises rapidly after the energization of the electric heater 40 is started. Specifically, the amount of refrigerant = 50 g and the amount of refrigerant = 100 g in FIG. 4 indicate the process of increasing the surface temperature of the accumulator 19 when the electric heater 40 is in an empty state.

  In FIG. 4, T1 is an emptying determination temperature of the electric heater 40, and only when the electric heater 40 heats the accumulator 19 in a state where the liquid refrigerant liquid level is not substantially formed in the accumulator 19 (in an empty state). The temperature to reach. This idling determination temperature T1 is a set value set in consideration of the output capacity of the electric heater 40, the volume of the accumulator 19, and the like. In the example of FIG. 4, T1 = 80 ° C., but this T1 is practical. It can be set in the range of about 50 ° C to 120 ° C.

  On the other hand, the amount of refrigerant = 150 g corresponds to a case where the liquid refrigerant liquid level is substantially formed in the accumulator 19 as shown in FIG. 5, and the heat generated by the electric heater 40 passes through the metal wall surface of the accumulator 19. Served for heating liquid refrigerant. Accordingly, the amount of heat transferred from the electric heater 40 to the refrigerant side is significantly increased as compared with the above-described idling, and the increase in the surface temperature of the accumulator 19 is suppressed. As a result, when the refrigerant amount = 150 g, as shown in FIG. 4, the surface temperature of the accumulator 19 is kept at a temperature lower than the air-flying determination temperature T1 even after a lapse of time after the energization of the electric heater 40 is started. The rise stops.

  As understood from the above, the degree of increase in the surface temperature of the accumulator 19 after the start of energization of the electric heater 40 is determined, and if the surface temperature of the accumulator 19 is less than the emptying determination temperature T1, the hot gas heater cycle It can be determined that the refrigerant amount in H is normal. On the other hand, if the surface temperature of the accumulator 19 rises above the emptying determination temperature T1, it can be determined that the amount of refrigerant in the hot gas heater cycle H is insufficient.

  Here, when the refrigerant is insufficient, the surface temperature of the accumulator 19 suddenly rises due to the occurrence of the empty state of the electric heater 40. Therefore, as shown in FIG. 4, a short time of about 10 seconds elapses after the start of energization of the electric heater 40. Can determine the lack of refrigerant.

  As shown in FIG. 5, when the refrigerant amount is 400 g or more, the tank main body 19a of the accumulator 19 is filled with the liquid refrigerant. In this full liquid state, all of the heat generated by the electric heater 40 is absorbed by the liquid refrigerant. Therefore, the surface temperature of the accumulator 19 when the liquid is full is the liquid refrigerant temperature in the accumulator 19, that is, the full liquid judgment temperature T2. The temperature is equivalent to

  Therefore, the surface temperature of the accumulator 19 when the refrigerant amount in FIG. 4 is 450 g (full liquid) is the liquid refrigerant temperature in the accumulator 19 from the outside air temperature (−10 ° C.) after the energization of the electric heater 40 is started. After rising to the full liquid determination temperature T2, the full liquid determination temperature T2 is maintained.

  The full liquid determination temperature T2 is a refrigerant saturation temperature determined by the low-pressure side pressure of the hot gas heater cycle H. Since the value of the low-pressure side pressure has the greatest influence of the outside air temperature, the full liquid determination temperature T2 can be estimated from the value of the outside air temperature. If the surface temperature of the accumulator 19 is still less than the full liquid determination temperature T2 after a predetermined time, for example, about 10 seconds after the start of energization of the electric heater 40, it is determined that the accumulator 19 is in a full liquid state. it can.

  Next, operation control in the hot gas heating mode according to the first embodiment will be described with reference to FIG. FIG. 6 is a control routine executed by the ECU 26, and shows a specific example of heating mode operation control including protection control of the compressor 10 based on the refrigerant shortage determination. FIG. 6 shows a subroutine for the main routine of the air conditioning control, which starts, for example, when the hot gas switch 29b of the air conditioning operation panel 28 is turned on.

  First, timer J and timer H are each initialized to 0 in step S100. Next, in step S110, a cooling mode is set, and a refrigerant recovery operation for recovering the stagnation refrigerant on the condenser (outdoor heat exchanger) 14 side is performed. Specifically, the cooling electromagnetic valve 13 is opened, the heating electromagnetic valve 21 is closed, the electric heater 40 is de-energized (OFF), and the compressor 10 (electromagnetic clutch 11) is operated (ON). State.

  The timer J in the next step S120 starts with the start of the refrigerant recovery operation. In step S120, it is determined whether or not the timer J has a predetermined time, for example, 30 seconds or less. While the time measured by the timer J is 30 seconds or less, the refrigerant recovery operation in step S110 is continued, and the stagnant refrigerant on the condenser (outdoor heat exchanger) 14 side is recovered to the hot gas heater cycle H side.

  This refrigerant recovery operation is performed in order to recover the refrigerant stagnated on the condenser 14 side while the cycle is stopped to the hot gas heater cycle H side. When the outside air temperature is extremely low such as −20 ° C. or lower, for example. Since the saturation pressure with respect to the outside air temperature of the refrigerant is reduced to a very small value, the difference in pressure between the refrigerant pressure in the condenser 14 and the suction pressure of the compressor 10 becomes small when the heating mode is started, and the condenser 14 side is reached. However, it is difficult to collect the stagnation refrigerant on the condenser 14 side when the heating mode is activated by setting the cooling mode.

  When the time measured by the timer J exceeds 30 seconds, the process proceeds from step S120 to step S130, and it is determined whether the outside air temperature (the temperature detected by the outside air temperature sensor 27b) is a predetermined temperature at an extremely low temperature, for example, −10 ° C. or less. When the outside air temperature is −10 ° C. or lower, the process proceeds to the next step S140, and a hot gas heating mode in which the electric heater 40 is energized (ON) is set. That is, the cooling electromagnetic valve 13 is closed, the heating electromagnetic valve 21 is opened, the electric heater 40 is energized (ON), and the compressor 10 (electromagnetic clutch 11) is activated (ON). Therefore, the liquid refrigerant heating by the heat generated by the electric heater 40 can be performed to improve the hot gas heating performance at an extremely low temperature.

  Then, in the next step S150, it is determined whether the surface temperature of the accumulator 19 (the temperature detected by the temperature sensor 42) is lower than the emptying determination temperature T1 shown in FIG. The idling determination temperature T1 is a fixed value set in advance based on the output capacity of the electric heater 40, the volume of the accumulator 19, and the like as described above.

  If the accumulator surface temperature is lower than the emptying determination temperature T1, the amount of refrigerant in the hot gas heater cycle H is normal as described above, so the hot gas heating mode in step S140 is continued.

  On the other hand, when the amount of the refrigerant in the hot gas heater cycle H is insufficient, the surface temperature of the accumulator 19 rises above the emptying determination temperature T1, so the determination in step S150 is NO, and the process proceeds to step S160. The compressor 10 is stopped. Thereby, it can prevent that the compressor 10 operate | moves with insufficient lubrication, and can protect the compressor 10 reliably.

  In step S160, a compressor stop flag is set and given to the main routine of air conditioning control. Therefore, after that, the stopped state of the compressor 10 can be maintained until the control routine of FIG. 6 starts again.

  On the other hand, when the outside air temperature is higher than −10 ° C., the process proceeds from step S130 to step S170, and the hot gas heating mode in which the electric heater 40 is in a non-energized (OFF) state is set. That is, the cooling electromagnetic valve 13 is closed, the heating electromagnetic valve 21 is opened, the electric heater 40 is de-energized (OFF), and the compressor 10 (electromagnetic clutch 11) is activated (ON). . In the hot gas heating mode in step S170, the hot gas heating performance is exhibited without heating the liquid refrigerant by the electric heater 40.

  In the hot gas heating mode, since the electric heater 40 is in a non-energized (OFF) state, the refrigerant shortage determination based on the surface temperature of the accumulator 19 cannot be performed.

  Therefore, the refrigerant shortage determination is performed based on the refrigerant pressure of the hot gas heater cycle H when the electric heater 40 is not energized. Specifically, in step S180, it is first determined whether the time measured by the timer H is a predetermined time, for example, 30 seconds or less. The timer H starts counting time by the activation of the hot gas heating mode in step S170, and continues the hot gas heating mode in step S170 as long as the time count of the timer H is 30 seconds or less. On the other hand, if the time measured by the timer H exceeds 30 seconds, the refrigerant shortage determination based on the refrigerant pressure is performed in step S190.

  The refrigerant shortage determination will be specifically described. When the refrigerant is short, the density of the refrigerant sucked into the compressor 10 is small. Therefore, compared to when the refrigerant amount is normal, the high pressure (compressor discharge pressure) and the low pressure ( Both the compressor suction pressure) are significantly reduced. Therefore, in the hot gas heating mode, the lack of refrigerant can be determined by detecting the decrease in the high pressure or the low pressure.

  Incidentally, the refrigerant pressure in step S190 is specifically the high pressure of the hot gas heater cycle H detected by the refrigerant pressure sensor 27d, while the high pressure P0 at the boundary between the refrigerant shortage region and the normal region is shown in FIG. As shown, it becomes a characteristic which falls according to the fall of outside temperature. That is, since the compressor 10 and the high-pressure piping section are disposed in the engine room of the vehicle and exposed to the outside air atmosphere, even if the refrigerant amount in the cycle is normal, the high-pressure pressure decreases as the outside air temperature decreases. . Therefore, the high pressure P0 at the boundary between the refrigerant shortage region and the normal region has a characteristic that decreases as the outside air temperature decreases.

  In addition, the refrigerant | coolant insufficient area | region shown in FIG. 7 is an area | region determined based on external temperature, and is mapped beforehand and memorize | stored in ROM of the microcomputer.

  When it is determined in step S190 that the high pressure is higher than the high pressure P0 at the boundary of the refrigerant shortage region, the amount of refrigerant is normal, so the hot gas heating mode in step S170 is continued. On the other hand, when it is determined in step S190 that the high pressure is equal to or lower than the high pressure P0 at the boundary of the refrigerant shortage region, the refrigerant amount is insufficient. Therefore, the process proceeds from step S190 to step S160, and the compressor 10 is stopped. Thereby, the compressor 10 can be protected by preventing the compressor 10 from operating with insufficient lubrication.

  Further, in the present embodiment, after step S180 is provided and the heating mode is activated, after a predetermined time (30 seconds) has passed, the process proceeds to step S190, and the lack of refrigerant is determined based on the high pressure pressure for the following reason. Because.

  That is, immediately after the heating mode is started, the difference between the high pressure and the low pressure is small when the refrigerant amount is normal and when the refrigerant is insufficient, but after a predetermined time (for example, 30 seconds) has elapsed after the heating mode is started, the refrigerant There is a large difference between the high pressure and the low pressure when the amount is normal and when the refrigerant is insufficient. Therefore, in the present embodiment, as described above, after the heating mode is started, after a predetermined time has elapsed, the refrigerant shortage is determined based on the high-pressure pressure to avoid the unstable transition period immediately after the heating mode is started. It can be judged accurately.

  According to the experimental study by the present inventor, when the normal range of the refrigerant amount in the hot gas heater cycle H is 150 g to 400 g as shown in FIG. 5, the refrigerant based on the surface temperature of the accumulator 19 when the electric heater 40 is energized. The shortage determination amount is about 100 g as shown in FIG. 5, whereas the refrigerant shortage determination amount based on the determination of the high pressure is a small amount of about 50 g.

  That is, since the high pressure varies depending on various factors, the high pressure P0 at the boundary of the refrigerant shortage region in Step S190 must be set low in order to avoid erroneous determination of refrigerant shortage.

(Second Embodiment)
As shown in FIG. 5, when the amount of refrigerant in the hot gas heater cycle H reaches 400 g or more, the accumulator 19 becomes full, liquid refrigerant is sucked into the suction side of the compressor 10, and the compressor 10 performs liquid compression. This may cause damage to the compressor 10.

  Therefore, in the second embodiment, the full liquid state in the accumulator 19 is also determined and the compressor 10 is stopped to prevent the compressor 10 from being damaged due to liquid compression.

  FIG. 8 shows a control routine according to the second embodiment, and only differences from FIG. 6 will be described. In step S100, the timer G is initialized to 0 in addition to the timers J and H. And the determination step S200 of the time measuring time of the timer G is added between step S140 and step S150. The timer G starts measuring time by starting the heating mode in step S140. In step S200, it is determined whether the time measured by the timer G is a predetermined time, for example, 10 seconds or less.

  When the time measured by the timer G exceeds 10 seconds, the process proceeds to step S150, and the refrigerant shortage determination based on the surface temperature of the accumulator 19 is performed. In this step S150, it is determined whether the surface temperature of the accumulator 19 is a temperature between the full liquid determination temperature T2 and the emptying determination temperature T1 in FIG. The full liquid determination temperature T2 is not a fixed value set in advance, but a variable value estimated based on the outside air temperature.

  Then, when the surface temperature of the accumulator 19 is a temperature between the full liquid determination temperature T2 and the emptying determination temperature T1, the amount of refrigerant is normal, so the hot gas heating mode in step S140 is continued. On the other hand, when the surface temperature of the accumulator 19 is higher than the emptying determination temperature T1, the refrigerant is insufficient, and thus the process proceeds to step S160 and the compressor 10 is stopped.

  On the other hand, when the surface temperature of the accumulator 19 is equal to or lower than the full liquid determination temperature T2, the accumulator 19 is in a full liquid state, so the process proceeds to step S160 and the compressor 10 is stopped. For this reason, according to 2nd Embodiment, the liquid compression of the compressor 10 which generate | occur | produces when the accumulator 19 is full can also be prevented beforehand.

  Even when the accumulator 19 is not fully filled (when the refrigerant amount is less than 400 g), the surface temperature of the accumulator 19 is not more than the full liquid determination temperature T2 as shown in FIG. . Therefore, by providing step S200 and avoiding the determination of step S150 immediately after the activation of the heating mode, it is possible to prevent erroneous determination of the full liquid state immediately after the activation of the heating mode.

  The full liquid state of the accumulator 19 in the second embodiment is not only the case where the internal volume of the accumulator 19 is completely filled with liquid refrigerant, but also the liquid level rises to the vicinity of the upper end opening 19d of the refrigerant outlet pipe 19c. Thus, a state in which the liquid refrigerant is filled up to a level at which the liquid refrigerant is led out from the upper end opening 19d is also included as a substantially full liquid state.

(Third embodiment)
Insufficient amount of refrigerant in the hot gas heater cycle H includes (1) a case where the refrigerant amount as a whole of the refrigeration cycle apparatus including the condenser 14 is originally insufficient due to leakage of refrigerant to the outside, and (2) the condenser 14. Even if the refrigerant recovery operation (step S110) for recovering the stagnation refrigerant to the side is performed, there are two cases where the refrigerant recovery fails for some reason. In the latter case, if the refrigerant recovery operation is executed again, the shortage of the refrigerant amount in the hot gas heater cycle H may be solved.

  Therefore, in the third embodiment, when it is determined that the amount of refrigerant in the hot gas heater cycle H is insufficient, the refrigerant recovery operation is performed again a predetermined number of times. FIG. 9 shows the operation control in the heating mode of the third embodiment, and only differences from FIGS. 6 and 8 will be described. In step S100, the timers J and H are initialized to 0, and the number of executions I of the refrigerant recovery operation is initialized to 0.

  Then, after step S120, step S210 for counting the number of executions I of the refrigerant recovery operation is provided, and after step S150, the number of executions I of the refrigerant recovery operation is a predetermined number, for example, 5 or less. A determination step S220 is provided.

  As a result, in the third embodiment, when it is determined in step S150 that the surface temperature of the accumulator 19 is equal to or higher than the emptying determination temperature T1, that is, a refrigerant shortage state is determined, first, the refrigerant recovery operation is performed in step S220. It is determined whether the number of times I is 5 or less. If the number of executions I of the refrigerant recovery operation is 5 times or less, the process proceeds from step S220 to step S110, and the refrigerant recovery operation is executed again to recover the stagnant refrigerant to the condenser 14 side, whereby the hot gas heater cycle H Attempts to eliminate the refrigerant shortage.

  When the cause of the refrigerant shortage is the latter (2), the refrigerant shortage is eliminated by re-executing the refrigerant recovery operation, and the liquid refrigerant liquid level is formed in the accumulator 19. As a result, since the surface temperature of the accumulator 19 falls below the emptying determination temperature T1, the determination in step S150 is YES, and the hot gas heating mode in step S140 is maintained.

  On the other hand, when the cause of the refrigerant shortage is the former (1), the refrigerant shortage is not solved even if the refrigerant recovery operation is re-executed, so the number of executions I of the refrigerant recovery operation reaches six. Then, determination of step S220 becomes NO, and it progresses to step S160 at this time, and the compressor 10 is stopped.

  As described above, according to the third embodiment, when the cause of the refrigerant shortage in the hot gas heater cycle H is the stagnant refrigerant to the condenser 14 side, the refrigerant recovery operation is re-executed to eliminate the refrigerant shortage. To continue the hot gas heating mode.

(Other embodiments)
1) In the above-described embodiment, the hot gas heater cycle H in which the refrigerant discharged from the compressor 10 is directly introduced into the evaporator (indoor heat exchanger) 18 through the hot gas bypass passage 20 and the evaporator 18 is operated as a radiator. Although the refrigeration cycle apparatus configured to execute the heating mode in which air is heated by the evaporator 18 by the hot gas heater cycle H has been described, the present invention may be applied to a well-known heat pump type refrigeration cycle apparatus.

  That is, in a well-known heat pump refrigeration cycle apparatus, an electric heater for heating liquid refrigerant is provided in an accumulator disposed between an outdoor heat exchanger serving as an evaporator and a compressor suction side in the heating mode, and heating capacity To improve. Then, a temperature sensor may be provided in the accumulator, and the lack of refrigerant may be determined based on the temperature detected by the temperature sensor.

  2) In the above embodiment, only the compressor 10 is stopped when the refrigerant shortage is determined. However, the refrigerant shortage may be displayed simultaneously with the stop of the compressor 10. As the refrigerant shortage display means, for example, an indicator lamp that is turned on when the refrigerant is short may be provided on the air conditioning operation panel 28.

  3) In the above embodiment, the electric heater 40 is used as the heating means for heating the liquid refrigerant in the accumulator 19, but hot water heated by an in-vehicle heating source (vehicle engine, combustion heater, etc.) is supplied. You may provide a warm water heater in the accumulator 19 as a heating means for liquid refrigerant heating.

  4) In the above embodiment, the electric heater 40 is energized when the outside air temperature is equal to or lower than the predetermined value in the heating mode. However, the physical quantity correlated with the outside air temperature, for example, the inside air temperature when the heating mode is activated, the heating mode The electric heater 40 may be energized when the engine water temperature or the like at the time of startup is equal to or lower than a predetermined value.

  5) In the above embodiment, the air conditioning operation panel 28 includes the dedicated hot gas switch 29b that is manually operated by the occupant, and the hot gas heating mode is set by turning on the hot gas switch 29b. Without providing the manual operation dedicated switch 29b, for example, the ECU 26 may determine the maximum heating state or the like and automatically activate the hot gas heating mode.

  Also, in a manually operated air conditioner, dial or lever temperature adjustment for manually operating temperature adjustment means such as an air mix door that adjusts the air volume ratio of cold / hot air and a hot water valve that adjusts the heater core hot water flow rate. Since the operation member is mounted on the air conditioning operation panel 28, the hot gas switch 29b may be turned on in conjunction with the operation of the temperature adjustment operation member to the maximum heating position. This eliminates the need for a dedicated operating member for the hot gas switch 29b.

1 is a system configuration diagram showing an overall configuration of a first embodiment of the present invention. It is a partial cross section figure showing the example of the accumulator by a 1st embodiment. It is a block diagram of electric control of a 1st embodiment. It is a graph which shows the relationship between the refrigerant | coolant amount in a hot gas heater cycle, and the raise degree of an accumulator surface temperature. It is a graph which shows the relationship between the refrigerant | coolant amount in a hot gas heater cycle, and the refrigerant | coolant liquid level height in an accumulator. It is a flowchart of hot gas heating mode control including the refrigerant | coolant shortage determination by 1st Embodiment. It is explanatory drawing of the refrigerant | coolant pressure determination in FIG. It is a flowchart of hot gas heating mode control including the refrigerant | coolant shortage determination by 2nd Embodiment. It is a flowchart of hot gas heating mode control including the refrigerant | coolant shortage determination by 3rd Embodiment.

Explanation of symbols

10 ... Compressor, 14 ... Condenser (outdoor heat exchanger),
16 ... Temperature expansion valve (cooling decompression device), 18 ... Evaporator (indoor heat exchanger),
19 ... Accumulator, 20 ... Hot gas bypass passage,
21a ... a diaphragm (a decompression device for heating), 40 ... an electric heater,
42 ... temperature sensor (temperature detection means), C ... refrigeration cycle for cooling,
H: Hot gas heater cycle.

Claims (7)

The refrigerant discharged from the compressor (10) is returned to the compressor (10) through the outdoor heat exchanger (14), the cooling decompression device (16), and the indoor heat exchanger (18), whereby the indoor heat A cooling refrigeration cycle (C) for operating the exchanger (18) as an evaporator;
The refrigerant discharged from the compressor (10) is introduced into the indoor heat exchanger (18) by a hot gas bypass passage (20) having a heating decompression device (21a) and then returned to the compressor (10). Thus, the indoor heat exchanger (18) is configured to be switchable with a hot gas heater cycle (H) that operates as a radiator,
The cooling mode is executed by blowing the air cooled by the indoor heat exchanger (18) by the cooling refrigeration cycle (C) into the room, and the indoor heat exchanger (H) by the hot gas heater cycle (H). 18) In the refrigeration cycle apparatus that executes the heating mode by blowing out the air heated in the room,
Between the outlet side of the indoor heat exchanger (18) and the suction side of the compressor (10), the gas-liquid refrigerant is separated to collect liquid refrigerant, and the gas refrigerant is sucked into the compressor (10). Installed accumulator (19) leading to the side,
The accumulator (19) includes heating means (40) for heating the liquid refrigerant in the accumulator (19) and temperature detecting means (42) for detecting the temperature of the accumulator (19) in the heating mode.
The temperature of the accumulator (19) when the accumulator (19) is heated by the heating means (40) in a state where the liquid level of the liquid refrigerant is not substantially formed inside the accumulator (19) is a first determination temperature. (T1)
The refrigeration cycle apparatus, wherein when the temperature detected by the temperature detection means (42) rises to the first determination temperature (T1) or higher during heating by the heating means (40), the refrigerant shortage is determined. The refrigeration cycle apparatus according to claim 1, wherein when the refrigerant shortage is determined, the compressor (10) is stopped. The cooling mode is set at the start of the heating mode, and the refrigerant recovery operation is performed to recover the stagnation refrigerant on the outdoor heat exchanger (14) side,
When the refrigerant shortage is determined, the refrigerant recovery operation is performed again a predetermined number of times, and the compressor (10) is stopped when the refrigerant shortage state is maintained even after the refrigerant recovery operation is re-executed. The refrigeration cycle apparatus according to claim 2. In the refrigeration cycle apparatus that executes a heating mode in which the indoor heat exchanger (18) is operated as a radiator by introducing the refrigerant discharged from the compressor (10) into the indoor heat exchanger (18),
An accumulator (19) is installed on the suction side of the compressor (10) to separate the gas and liquid of the refrigerant and store the liquid refrigerant and lead the gas refrigerant to the suction side of the compressor (10),
The accumulator (19) includes a heating means (40) for heating the liquid refrigerant in the accumulator (19) and a temperature detection means (42) for detecting the temperature of the accumulator (19) in the heating mode.
The temperature of the accumulator (19) when the accumulator (19) is heated by the heating means (40) in a state where the liquid level of the liquid refrigerant is not substantially formed inside the accumulator (19) is a first determination temperature. (T1)
The refrigeration cycle apparatus, wherein when the temperature detected by the temperature detection means (42) rises to the first determination temperature (T1) or higher during heating by the heating means (40), the refrigerant shortage is determined. The temperature of the accumulator (19) at the time of heating by the heating means (40) and when the accumulator (19) is fully filled with the liquid refrigerant is a second determination temperature (T2),
When the temperature detected by the temperature detecting means (42) is equal to or lower than the second determination temperature (T2) during the heating by the heating means (40), the full state of the accumulator (19) is determined and the compressor ( The refrigeration cycle apparatus according to any one of claims 1 to 4, wherein 10) is stopped. The heating means is an electric heater (40), and the electric heater (40) is energized when a physical quantity correlated with an outside air temperature is equal to or less than a predetermined value in the heating mode. The refrigeration cycle apparatus according to any one of claims 1 to 5. The refrigeration cycle apparatus according to claim 6, wherein when the electric heater (40) is not energized in the heating mode, the refrigerant shortage is determined when the refrigerant pressure falls below a predetermined value.

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