JP2010048459A - Refrigerating cycle device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a refrigerating cycle device accurately determining the refrigerant shortage state regardless of specifications of cycle subassemblies. <P>SOLUTION: Refrigerant evaporation temperature of an evaporator for making refrigerant side cooling capacity Qer calculated from a circulating refrigerant flow rate Gr of a cycle and outside air temperature Tam and air side cooling capacity Qea calculated from blowing air quantity Ga to the evaporator, suction side air temperature Tein and heat exchange fin temperature Tef1 of the evaporator equal to each other is, defined as estimated refrigerant evaporation temperature Tef2. When an absolute value of a difference between the estimated refrigerant evaporation temperature Tef2 and heat exchange fin temperature Tef1 detected as the actual refrigerant evaporation temperature exceeds a reference difference KTef, the refrigerant is determined to be in a shortage state. Thus, regardless of the specifications of the cycle sub-assemblies, the refrigerant shortage state can be accurately determined. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a refrigeration cycle apparatus configured to be able to determine a refrigerant shortage state in which a refrigerant circulating in a cycle is insufficient.

  Conventionally, Patent Document 1 discloses a refrigeration cycle apparatus configured to be able to determine a refrigerant shortage state in which a refrigerant circulating in the cycle is insufficient. In the refrigeration cycle apparatus of Patent Document 1, a variable displacement compressor including a capacity control valve that changes a discharge capacity in accordance with a differential pressure ΔP between a discharge pressure and a suction pressure is employed as a compressor.

Then, the refrigerant evaporation temperature is obtained by using the value Pd−ΔP obtained by subtracting the above-described differential pressure ΔP from the high-pressure refrigerant pressure Pd detected by the high-pressure sensor as the refrigerant evaporation pressure in the evaporator. The refrigerant shortage state is determined by comparing the blown air temperature detected by the air temperature sensor.
JP 2007-17110 A

  Incidentally, as described in paragraph 0042 of Patent Document 1, the capacity control valve of Patent Document 1 has an electromagnetic mechanism that generates an electromagnetic force corresponding to a control current value output from the control device. The valve body is displaced by a balance between the electromagnetic force generated by the electromagnetic mechanism and the force generated by the differential pressure.

  And in the refrigerating cycle device of patent documents 1, the differential pressure deltaP itself is controlled simultaneously with controlling the discharge capacity of a variable capacity type compressor by changing the control current value. That is, since the target differential pressure between the discharge pressure and the suction pressure is determined by determining the control current value, the differential pressure ΔP can be detected based on this control current value.

  However, Patent Document 1 discloses specifications of cycle components such as a compressor and a capacity control valve, such as a refrigeration cycle apparatus having a different control mode of the capacity control valve, or a refrigeration cycle apparatus not provided with a capacity control valve. No specific differential pressure detecting means in different refrigeration cycle apparatuses is described.

  That is, Patent Document 1 does not disclose any determination of a refrigerant shortage state in refrigeration cycle apparatuses having different specifications of cycle components such as a compressor and a capacity control valve.

  In view of the above points, an object of the present invention is to provide a refrigeration cycle apparatus that can accurately determine a refrigerant shortage state regardless of the specifications of the cycle component equipment.

In order to achieve the above object, according to the first aspect of the present invention, a compressor (11) that compresses and discharges a refrigerant, and a radiator (12) that dissipates heat from the refrigerant discharged from the compressor (11), To the decompressor (13) for decompressing the refrigerant radiated by the radiator (12), the evaporator (14) for evaporating the refrigerant decompressed by the decompressor (13), and the evaporator (14) A blower (14a) for blowing air to exchange heat with the refrigerant, a flow rate detecting means (20a) for detecting a physical quantity having a correlation with a circulating refrigerant flow rate circulating in the cycle, and an outside air temperature detecting means for detecting the temperature of the outdoor air (21), a blowing amount detecting means (20b) for detecting a physical quantity having a correlation with the blowing air amount blown from the blower (14a), and a suction side for detecting the temperature of the air blown to the evaporator (14) Temperature detection means (24), steam A blowing side temperature detecting means (25) for detecting the temperature of the air blown from the vessel (14), a detected circulating refrigerant flow rate (Gr) detected by at least the flow rate detecting means (20a), and an outside air temperature detecting means ( 21) Refrigerant-side capacity calculating means (S6) for calculating the refrigerant-side cooling capacity (Qer) using the detected outside air temperature (Tam) detected by 21), and at least the detected blown air detected by the air volume detecting means (20b) Using the amount (Ga), the detected suction-side air temperature (Tein) detected by the suction-side temperature detecting means (24), and the detected outlet-side air temperature (Tef1) detected by the outlet-side temperature detecting means (25) The air side capacity calculating means (S7) for calculating the air side cooling capacity (Qea) and the evaporator (1) having the same air side cooling capacity (Qea) and refrigerant side cooling capacity (Qer) ) Evaporating temperature estimating means (S8) that makes the estimated refrigerant evaporating temperature (Tef2), and refrigerant shortage determining means (S9) for determining that the refrigerant circulating in the cycle is insufficient. )
The refrigerant shortage determining means (S9), when the absolute value of the difference between the estimated refrigerant evaporation temperature (Tef2) and the detected outlet air temperature (Tef1) is equal to or greater than a predetermined reference difference (KTef), A refrigeration cycle apparatus that determines that the refrigerant is in a shortage state is characterized.

  According to this, the estimated refrigerant evaporation temperature (Tef2) is defined as the estimated refrigerant evaporation temperature (Tef2), which is the refrigerant evaporation temperature of the evaporator (14) in which the air-side cooling capacity (Qea) and the refrigerant-side cooling capacity (Qer) are equal. Since the refrigerant shortage state is determined by comparing the actual refrigerant evaporation temperature and the equal detected blowing side air temperature (Tef1), the refrigerant shortage state is reduced to that level regardless of the specifications of the cycle component equipment. Accordingly, it can be determined with high accuracy.

  That is, when the refrigerant is slightly insufficient, the detected blowout side air temperature (Tef1) is lower than the temperature of the refrigerant flowing out of the evaporator (14), so that the refrigerant side capacity calculation means (S6) performs the actual refrigerant side cooling. The refrigerant side cooling capacity (Qer) is calculated smaller than the capacity. For this reason, as will be described in detail in an embodiment to be described later, the estimated refrigerant evaporation temperature (Tef2) is estimated to be higher than the detected outlet-side air temperature (Tef1), and the refrigerant shortage state can be detected.

  On the other hand, when the refrigerant is largely insufficient, the difference between the detected suction side air temperature (Tein) and the detected outlet side air temperature (Tef1) becomes small, so that the air side capacity calculating means (S7) The air side cooling capacity (Qea) is calculated to be smaller than the cooling capacity. For this reason, as will be described in detail in an embodiment to be described later, the estimated refrigerant evaporation temperature (Tef2) is estimated to be lower than the detected outlet air temperature (Tef1), and the refrigerant shortage state can be detected.

  As a result, the refrigerant shortage state can be accurately determined according to the degree, regardless of the specifications of the cycle component equipment.

  According to a second aspect of the present invention, in the refrigeration cycle apparatus according to the first aspect, the discharge capacity changing means (11a) for changing the refrigerant discharge capacity of the compressor (11) and the operation of the discharge capacity changing means (11a) A discharge capacity control means (20c) for controlling the discharge capacity and a warning means (34) for warning the user when the refrigerant shortage determination means (S9) determines that the refrigerant is in a shortage state. The means (20c) reduces the refrigerant discharge capacity when it is determined that the refrigerant is in a shortage state and when the detected outlet air temperature (Tef1) is higher than the estimated refrigerant evaporation temperature (Tef2). It is characterized by.

  According to this, when it is determined that the refrigerant is in a shortage state, not only can this be recognized by the user, but also when the detected outlet air temperature (Tef1) is higher than the estimated refrigerant evaporation temperature (Tef2). Since the discharge capacity control means (20c) lowers the refrigerant discharge capacity, the compressor (11) can be protected when the refrigerant sealed in the cycle is largely insufficient.

  On the other hand, when the detected outlet side air temperature (Tef1) is not higher than the estimated refrigerant evaporation temperature (Tef2), that is, when the refrigerant is slightly insufficient, the refrigerant discharge capacity of the compressor (11) is not lowered. Therefore, the refrigeration cycle apparatus can continuously exhibit the cooling capacity while allowing the user to recognize that the refrigerant is in a shortage state.

  In addition, “reducing refrigerant discharge capacity” in this claim not only means reducing the pressure and flow rate of refrigerant discharged from the compressor (11), but also operating the compressor (11). This also includes stopping the operation.

  According to a third aspect of the present invention, in the refrigeration cycle apparatus according to the first aspect, the discharge capacity changing means (11a) for changing the refrigerant discharge capacity of the compressor (11) and the operation of the discharge capacity changing means (11a) The discharge capacity control means (20c) controls the discharge capacity control means (20c), and the discharge capacity control means (20c) reduces the refrigerant discharge capacity when it is determined that the refrigerant is in a shortage state. According to this, when it is determined that the refrigerant is in a shortage state, the compressor (11) can be reliably protected.

  Specifically, as in the invention according to claim 4, in the refrigeration cycle apparatus according to claim 2 or 3, the compressor is a variable capacity compressor (11) configured to be capable of changing the discharge capacity. The discharge capacity changing means is a capacity control valve (11a) for changing the discharge capacity, and the flow rate detecting means is a control signal (from the discharge capacity control means (20c) to the capacity control valve (11a) ( Ic) is detected.

  According to this, since the control signal (Ic) is a physical quantity having a correlation with the circulating refrigerant flow rate circulating in the cycle, the circulating refrigerant flow rate circulating in the cycle can be easily detected.

  According to a fifth aspect of the present invention, in the refrigeration cycle apparatus according to the first aspect, when the refrigerant shortage determining means (S9) determines that the refrigerant is in a shortage state, a warning means for warning the user of this. (34). According to this, when it is determined that the refrigerant is in a shortage state, this can be recognized by the user.

  As in the sixth aspect of the present invention, in the refrigeration cycle apparatus according to any one of the first to fifth aspects, the refrigerant side capacity calculating means (S6) further determines the detected outlet side air temperature (Tef1). It may be used to calculate the refrigerant side cooling capacity (Qer). Thereby, the refrigerant side cooling capacity can be calculated with high accuracy, and the refrigerant shortage state can be determined with higher accuracy.

  As in the invention described in claim 7, in the refrigeration cycle apparatus according to any one of claims 1 to 6, the air-side capacity calculating means (S7) further includes a specific heat (Ca) of air and an evaporator. The air-side cooling capacity (Qer) may be calculated using at least one of the heat exchange efficiencies (φe) of (14). Thereby, since the air side cooling capacity can be calculated with high accuracy, the refrigerant shortage state can be determined with higher accuracy.

  As in the eighth aspect of the invention, in the refrigeration cycle apparatus according to any one of the first to seventh aspects, the reference difference (KTef) is calculated based on whether the detected outlet side air temperature (Tef1) is the estimated refrigerant evaporation temperature ( When lower than Tef2), the refrigerant shortage determining means (S9) is set to a value that can determine that the refrigerant is in a shortage state. Thereby, the grade of a refrigerant | coolant insufficient state can be determined reliably with sufficient precision.

  Further, in the refrigeration cycle apparatus having the above-described characteristics, as in the ninth aspect of the invention, the compressor (11) may be configured to increase the pressure of the refrigerant until the critical pressure or higher. As in the invention described in item 10, the refrigerant may be carbon dioxide.

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

(First embodiment)
A first embodiment of the present invention will be described with reference to FIGS. In this embodiment, the refrigeration cycle apparatus 10 of the present invention is applied to a vehicle air conditioner. FIG. 1 is an overall configuration diagram of a refrigeration cycle apparatus 10 according to the present embodiment.

  The refrigeration cycle apparatus 10 employs carbon dioxide as a refrigerant, and constitutes a supercritical refrigeration cycle in which the discharge refrigerant pressure of the compressor 11 is equal to or higher than the critical pressure of the refrigerant (supercritical state). Furthermore, this refrigerant is mixed with refrigerating machine oil for lubricating the compressor 11, and this refrigerating machine oil circulates in the cycle together with the refrigerant.

  The compressor 11 sucks, compresses and discharges the refrigerant in the refrigeration cycle apparatus 10, and is driven to rotate by a driving force transmitted from a vehicle travel engine (not shown) via a pulley and a belt. .

  The compressor 11 is a well-known swash plate type variable displacement compressor configured such that the discharge capacity can be continuously changed by a control signal output from an air conditioning control device 20 described later. The discharge capacity is the geometric volume of the working space where the refrigerant is sucked and compressed, that is, the cylinder volume between the top dead center and the bottom dead center of the piston stroke.

  Specifically, the compressor 11 includes a swash plate chamber (not shown) that introduces suction refrigerant and discharge refrigerant, an electromagnetic capacity control valve 11a that adjusts the ratio of suction refrigerant and discharge refrigerant introduced into the swash plate chamber, It has a swash plate (not shown) that displaces the tilt angle in accordance with the pressure in the swash plate chamber. The piston stroke (discharge capacity) is changed according to the inclination angle of the swash plate.

  The electromagnetic capacity control valve 11a includes a pressure responsive mechanism that generates a force due to a differential pressure between the suction refrigerant pressure and the discharge refrigerant pressure of the compressor 11, and an electromagnetic mechanism that generates an electromagnetic force opposite to the force due to the differential pressure. It is built in and adjusts the valve opening (ratio of suction refrigerant and discharge refrigerant) by the balance between the force due to the differential pressure and the electromagnetic force to change the pressure in the swash plate chamber.

  Further, the electromagnetic force of the electromagnetic mechanism is determined by the control current Ic output from the air conditioning controller 20, and when the control current Ic is increased, the pressure in the swash plate chamber decreases and the inclination angle of the swash plate increases. Thereby, piston stroke (discharge capacity) increases. Conversely, when the control current Ic is decreased, the pressure in the swash plate chamber increases and the tilt angle of the swash plate decreases. Thereby, piston stroke (discharge capacity) decreases.

  And since the refrigerant | coolant discharge capability of the compressor 11 will increase / decrease according to the increase / decrease in this discharge capacity | capacitance, in this embodiment, the electromagnetic capacity | capacitance control valve 11a comprises a discharge capability change means. Further, the relationship between the control current Ic and the discharge flow rate of the compressor 11 in the present embodiment increases as the control current Ic increases as shown in the characteristic diagram of FIG.

  Therefore, the control current Ic of this embodiment is a physical quantity having a correlation with the circulating refrigerant flow rate circulating in the cycle. In the air conditioning control device 20, the control current Ic is detected by the flow rate detection circuit 20a as the flow rate detection means. Thus, the circulating refrigerant flow rate Gr is obtained. JP, 2001-173556, A, etc. can be referred to for a capacity control valve and a variable capacity compressor configured to have such a circulating refrigerant flow rate control function.

  Further, since the discharge capacity of the compressor 11 of this embodiment can be reduced to about 0%, as described above, the clutch 11 has a clutchless configuration in which the compressor 11 is always connected to the vehicle running engine via a pulley and a belt. can do. Of course, power may be transmitted from the vehicle running engine via the electromagnetic clutch.

  A radiator 12 is connected to the refrigerant discharge side of the compressor 11. The radiator 12 is a heat-dissipating heat exchanger that performs heat exchange between the high-temperature and high-pressure refrigerant discharged from the compressor 11 and the outside air (air outside the passenger compartment) blown by the cooling fan 12a to radiate the high-pressure refrigerant.

  The cooling fan 12a is an electric blower in which the rotation speed (the amount of blown air) is controlled by a control voltage output from an air conditioning control device 20 described later. In the refrigeration cycle apparatus 10 of the present embodiment, a supercritical refrigeration cycle is configured, so that the refrigerant passing through the radiator 12 radiates heat in a supercritical state without condensing.

  A pressure control valve 13 is connected to the outlet side of the radiator 12. The pressure control valve 13 functions as a decompression means for decompressing the high-pressure refrigerant flowing out of the radiator 12, and the high-pressure side refrigerant pressure is set to a target high pressure that substantially maximizes the coefficient of performance (COP) of the cycle. The valve opening (throttle opening) functions as a high-pressure control means that is adjusted by a mechanical mechanism.

  Specifically, the pressure control valve 13 has a temperature sensing part 13a provided between the radiator 12 outlet side and the pressure control valve 13 inlet side, and the radiator 12 outlet is provided inside the temperature sensing part 13a. A pressure corresponding to the temperature of the high-pressure refrigerant on the side is generated, and the valve opening degree of the pressure control valve 13 is adjusted by the balance between the internal pressure of the temperature sensing portion 13a and the refrigerant pressure on the outlet side of the radiator 12.

  Thereby, the high pressure side refrigerant pressure can be adjusted to a target high pressure determined by the high pressure side refrigerant temperature on the outlet side of the radiator 12. For the pressure control valve 13 having such a high pressure control function, reference can be made to JP-A-2000-81157.

  An evaporator 14 is connected to the outlet side of the pressure control valve 13. The evaporator 14 is an endothermic heat exchanger that exchanges heat between the low-pressure refrigerant decompressed by the pressure control valve 13 and the blown air blown from the blower fan 14a, and evaporates the low-pressure refrigerant to exert an endothermic effect. is there.

  The blower fan 14a is an electric blower whose rotation speed (amount of blown air) is controlled by a control voltage BLV output from the air conditioning control device 20. Therefore, the control voltage BLV of the present embodiment is a physical quantity that has a correlation with the amount of air blown from the blower fan 14a to the evaporator 14, and the air conditioning controller 20 uses the control voltage BLV as a blower amount detection unit. The air volume detection circuit 20b detects the air volume Ga.

  The evaporator 14 is arranged in a case (not shown) that forms an air passage for the air blown into the vehicle interior in the indoor air conditioning unit of the vehicle air conditioner. A heater core, which is a heating means for reheating the blown air by exchanging heat between the blown air cooled by the evaporator 14 and the engine coolant, is disposed. As a result, the temperature of the air blown into the passenger compartment that is air-conditioned space is adjusted.

  An accumulator 15 is connected to the refrigerant outlet side of the evaporator 14. The accumulator 15 is a gas-liquid separator that separates the refrigerant flowing out of the evaporator 14 into a liquid phase refrigerant and a gas phase refrigerant and stores excess liquid phase refrigerant in the cycle. Further, the accumulator 15 is provided with a gas phase refrigerant outlet through which the gas phase refrigerant flows out, and this gas phase refrigerant outlet is connected to the refrigerant suction side of the compressor 11.

  Next, an outline of the electric control unit of the present embodiment will be described. The air conditioning control device 20 includes a known microcomputer including a CPU, a ROM, a RAM, and the like and peripheral circuits thereof. Then, various calculations and processes are performed based on the control program stored in the ROM, and the operations of the above-described various electric actuators 11a, 12a, 14a and the like are controlled.

  The air conditioning control device 20 is integrally configured with control means for controlling various electric actuators. In the present embodiment, in particular, the operation of the electromagnetic capacity control valve 11a in the air conditioning control device 20 is performed. The configuration of hardware and software to be controlled is the discharge capacity control means 20c.

  In addition, air conditioning sensor groups 21 to 26 and an operation panel 30 disposed in the passenger compartment are connected to the input side of the air conditioning control device 20, and the detection signals of the air conditioning sensor groups 21 to 26 and the operation panel 30 are connected to the input side. Operation signals and the like of the various operation switches 31 to 33 provided are input.

  Specifically, the air conditioning sensor group includes an outside air temperature sensor 21 that detects the outside air temperature Tam, an inside air temperature sensor 22 that detects the inside air temperature Tr, a solar radiation sensor 23 that detects the amount of solar radiation Ts incident on the vehicle interior, and a blower fan. The suction side air temperature sensor 24 as a suction side temperature detecting means for detecting the suction side air temperature Tein blown toward the evaporator 14 from 14a, and the blowout side temperature for detecting the blowout side air temperature blown from the evaporator 14 A blowing side air temperature sensor 25 as a detecting means, a high pressure sensor 26 for detecting the discharge refrigerant pressure Pd discharged from the compressor 11, and the like are provided.

  In this embodiment, the thermistor attached to the heat exchange fin of the evaporator 14 is adopted as the blowout air temperature sensor 25, and the heat exchange fin temperature Tef1 in the vicinity of the refrigerant inlet of the evaporator 14 is detected. ing.

  Specifically, the operation switch of the operation panel 30 includes an air conditioner switch 31 that outputs an operation command signal for the vehicle air conditioner, an auto switch 32 that outputs an automatic control request signal for requesting automatic control of the air conditioning state, and a space to be cooled. A temperature setting switch 33 or the like serving as target temperature setting means for setting a target temperature Tset in the vehicle interior is provided.

  Further, on the display panel of the operation panel 30, when the refrigerant shortage determining means described later determines that the refrigerant circulating in the cycle is insufficient, the warning means for warning the passenger A warning light 34 is provided.

  The output side of the air conditioning controller 20 is connected to the electromagnetic capacity control valve 11a of the compressor 11, the electric fan such as the cooling fan 12a, the electric motor of the blower fan 14a, and the input side of the operation panel 30. The operation of the device is controlled by the output signal of the air conditioning controller 20.

  Next, the operation of this embodiment having the above configuration will be described with reference to FIG. FIG. 3 is a flowchart showing a control process executed by the air conditioning control device 20. This control process starts when the auto switch 32 is turned on (ON) in a state where a vehicle start switch (ignition switch) (not shown) is turned on.

  First, as shown in FIG. 3, in step S1, flags and timers are initialized, and in the next step S2, the detection signals detected by the sensor groups 21 to 26 and the operation signals of the operation panel 30 are displayed. Read.

Next, in step S3, a target blowing temperature TAO of the vehicle cabin blowing air is calculated. The target blowing temperature TAO is calculated by the following formula F1 based on the air conditioning thermal load fluctuation and the set temperature Tset set by the temperature setting switch 33.
TAO = Kset × Tset−Kr × Tr−Kam × Tam−Ks × Ts + C (F1)
Kset, Kr, Kam, and Ks are control gains, and C is a correction constant.

  Next, in step S4, control states of various air conditioning control devices excluding the compressor 11 are determined. That is, among various electric actuators connected to the output side of the air conditioning control device 20, the control signal output to the electric motor of the cooling fan 12a, excluding the electromagnetic capacity control valve 11a, and the output to the electric motor of the blower fan 14a The control signal to be determined is determined.

  For example, for the control signal (control voltage BLV) output to the electric motor of the blower fan 14a, based on the target blowing temperature TAO, refer to the control map stored in advance in the air conditioning control device 20, and according to the TAO. Decide to obtain an appropriate air flow.

  More specifically, the control voltage BLV is set to the maximum value in the extremely low temperature range (maximum cooling range) and the extremely high temperature range (maximum heating range) of TAO, and the air flow rate is set to the maximum air volume. As the TAO rises from the extremely low temperature range toward the intermediate temperature range, or as the TAO decreases from the extremely high temperature range toward the intermediate temperature range, the control voltage BLV is decreased to reduce the air flow rate. Further, when TAO enters a predetermined intermediate temperature range, the control voltage BLV is set to the minimum value, and the air volume is set to the minimum air volume.

  Next, in step S5, the target refrigerant evaporation temperature TEO in the evaporator 14 is determined, and the refrigerant discharge capacity of the compressor 11 is determined. Specifically, based on the target blowing temperature TAO, a control map stored in advance in the air conditioning control device 20 is referred to determine so that the target refrigerant evaporation temperature TEO increases as TAO increases.

  Then, a deviation En (Te-TEO) between the heat exchange fin temperature Tef1 detected by the blowout air temperature sensor 25 and the target refrigerant evaporation temperature TEO is calculated, and based on this deviation En, Tef1 approaches TEO. The control current Ic to be output to the electromagnetic capacity control valve 11a is determined by a feedback control method based on proportional-integral control (PI control).

  Next, in step S6, the refrigerant side cooling capacity Qer is calculated. The refrigerant-side cooling capacity Qer is the total amount of heat that the refrigerant absorbs from the air in the evaporator 14.

This refrigerant side cooling capacity Qer is detected by the circulating refrigerant flow rate Gr obtained from the control current Ic detected by the flow rate detection circuit 20a, the outside air temperature Tam detected by the outside air temperature sensor 21, and the blowout side air temperature sensor 25. Based on the heat exchange fin temperature Tef1 that has been performed, it is calculated by the following mathematical formula F2.
Qer = Gr × Ie (F2)
Here, Ie is an enthalpy difference between the outlet side enthalpy Ieo of the evaporator 14 outlet side refrigerant and the inlet side enthalpy Iei of the evaporator 14 inlet side refrigerant. Details of this Ie will be described with reference to FIG. FIG. 4 is a Mollier diagram showing the state of the refrigerant during normal operation of the refrigeration cycle apparatus 10 of the present embodiment.

  In FIG. 4, the point Ro has shown the state of the refrigerant | coolant of the radiator 12 exit side. Since the refrigerant temperature at this point Ro is generally substantially equal to the outside air temperature Tam, the inlet side enthalpy Iei can be estimated from the outside air temperature Tam. Further, since the accumulator 15 is connected to the outlet of the evaporator 14, the refrigerant evaporation pressure of the evaporator 14 is estimated from the heat exchange fin temperature Tef1, and the outlet side enthalpy Ieo is estimated from the intersection with the saturated gas line. Can do.

  Therefore, the control step S6 in the present embodiment constitutes a refrigerant side capacity calculating means. In the refrigeration cycle apparatus 10 that employs carbon dioxide as the refrigerant as in the present embodiment, the gradient of the saturated gas line is large, and the change in Ieo with respect to the change in the refrigerant evaporation pressure of the evaporator 14 is small.

  Therefore, Ieo may be stored in the air conditioning controller 20 as a fixed value, and the refrigerant side cooling capacity Qer may be calculated. In this case, the refrigerant side cooling capacity Qer can be calculated without using the heat exchange fin temperature Tef1 detected by the blowout side air temperature sensor 25.

  Next, in step S7, the air-side cooling capacity Qea is calculated. The air-side cooling capacity Qea is the total amount of heat that air radiates to the refrigerant in the evaporator 14.

This air-side cooling capacity Qea is the air exchange amount detected by the blown air temperature sensor 25, the blown air amount Ga detected by the blown air amount detection circuit 20b, the suction side air temperature Tein detected by the suction side air temperature sensor 24, and the heat exchange. Based on the fin temperature Tef1 and the like, it is calculated by the following mathematical formula F3.
Qea = φe · Ca · Ga (Tein−Tef1) (F3)
Here, φe is the heat exchange efficiency of the evaporator 14, and Ca is the specific heat of air.

  Therefore, the control step S7 in the present embodiment constitutes an air side capacity calculating means. Instead of φe and Ca, the air-side cooling capacity Qea may be calculated using a value stored in advance in the air conditioning control device 20 as a correction constant.

  Next, in step S8, the estimated evaporative refrigerant temperature Tef2 is estimated based on the refrigerant side cooling capacity Qer and the air side cooling capacity Qea calculated in steps S6 and S7. Details of the estimation of the estimated evaporative refrigerant temperature Tef2 will be described with reference to FIG.

  The horizontal axis in FIG. 5 indicates the refrigerant evaporation temperature (refrigerant evaporation pressure) in the evaporator 14, and the vertical axis indicates the cooling capacity. Further, the solid line indicates the change in the refrigerant side cooling capacity Qer due to the refrigerant evaporation temperature, and the broken line indicates the change in the air side cooling capacity Qea due to the refrigerant evaporation temperature.

  As described above, the refrigerant-side cooling capability Qer is the total amount of heat that the refrigerant absorbs from the air in the evaporator 14, and the air-side cooling capability Qea is the total amount of heat that the air radiates to the refrigerant in the evaporator 14. Therefore, in the evaporator 14, heat exchange is performed at a balance point (a point where the refrigerant side cooling capacity Qer = air side cooling capacity Qea).

  Therefore, in step S8, the refrigerant evaporation temperature at which Qer = Qea is estimated as the estimated refrigerant evaporation temperature Tef2. Therefore, the control step S8 in the present embodiment constitutes an evaporation temperature estimating means.

  Next, in step S9, it is determined whether or not the absolute value of the difference between the estimated refrigerant evaporation temperature Tef2 and the heat exchange fin temperature Tef1 is equal to or greater than a predetermined reference difference KTef. If the absolute value of the difference between the estimated refrigerant evaporation temperature Tef2 and the heat exchange fin temperature Tef1 is equal to or greater than the reference difference KTef, it is determined that the refrigerant circulating in the cycle is insufficient and the process proceeds to step S10. move on.

  Therefore, the control step S9 in the present embodiment constitutes a refrigerant shortage determination unit. Details of the reference difference KTef will be described later. Further, in step S10, the warning lamp 34 is turned on and the process proceeds to step S11. In step S11, it is determined whether or not the estimated refrigerant evaporation temperature Tef2 is higher than the heat exchange fin temperature Tef1.

  If the heat exchange fin temperature Tef1 is higher than the estimated refrigerant evaporation temperature Tef2 in step S11, the refrigerant is largely insufficient to the extent that the refrigerant flowing into the evaporator 14 is almost in a gas phase. Proceed to step S12. In this way, if the refrigerant is largely insufficient, the refrigeration oil mixed in the refrigerant to lubricate the compressor 11 cannot be returned to the compressor 11, resulting in insufficient lubrication of the compressor 11 and its durability. Adversely affects lifespan.

  Therefore, in step S12, the refrigerant discharge capacity of the compressor 11 is reduced and the process proceeds to step S13. Specifically, in step S12 of the present embodiment, the control current Ic is changed so that the refrigerant discharge capacity becomes 0, and the operation of the compressor 11 is substantially stopped.

  On the other hand, if the heat exchange fin temperature Tef1 is not higher than the estimated refrigerant evaporation temperature Tef2 in step S11, the refrigerant is slightly insufficient to the extent that the refrigerant flowing into the evaporator 14 is in a gas-liquid two-phase state. As a result, the process proceeds to step S13. As long as the refrigerant is slightly insufficient in this way, the refrigerating machine oil can be returned to the compressor 11 without adversely affecting the durable life of the compressor 11.

  In step S9, if the absolute value of the difference between the estimated refrigerant evaporation temperature Tef2 and the heat exchange fin temperature Tef1 is not equal to or greater than the reference difference KTef, it is determined that the refrigerant is not short and the process proceeds to step S13.

  In step S13, a control signal is output from the air conditioning control device 20 to the electric actuator so that the control state determined in steps S4, S5, and S12 is obtained. In the next step S14, the process waits for the control period τ, and when it is determined that the control period τ has elapsed, the process returns to step S2.

  Therefore, in this embodiment, when it is determined in the control step S9 that constitutes the refrigerant shortage determining means that the refrigerant is not in a shortage state, the refrigerant discharged from the compressor 11 is transferred to the radiator 12. The heat is released and the pressure is reduced by the pressure control valve 13. At this time, the opening degree of the pressure control valve 13 is controlled so that the high-pressure side refrigerant pressure becomes a target high pressure at which the COP is substantially maximized, so that the refrigeration cycle apparatus 10 can be operated while exhibiting a high COP. it can.

  The refrigerant depressurized by the pressure control valve 13 flows into the evaporator 14. And the refrigerant | coolant which flowed into the evaporator 14 absorbs heat from vehicle interior blowing air, and evaporates. Thereby, vehicle interior blowing air can be cooled. The refrigerant evaporated in the evaporator 14 is gas-liquid separated in the accumulator 15, and the gas-phase refrigerant flowing out of the accumulator 15 is sucked into the compressor 11 and compressed again.

  Further, in the present embodiment, in the control step S9 constituting the refrigerant shortage determining means, the refrigerant evaporating temperature of the evaporator 14 at which the air side cooling capacity Qea and the refrigerant side cooling capacity Qer are equal is assumed as the estimated refrigerant evaporating temperature Tef2. Since the refrigerant shortage state is determined by comparing the refrigerant evaporation temperature Tef2 with the heat exchange fin temperature Tef1 that is equal to the actual refrigerant vaporization temperature, the refrigerant shortage state is determined according to the degree, regardless of the specifications of the cycle component equipment. Judgment can be made with high accuracy.

  This will be described in more detail with reference to FIG. FIG. 6 shows the measured value of the heat exchange fin temperature Tef1 (thick solid line), the estimated refrigerant evaporation temperature Tef2 (thick one-dot chain line), and the actually measured refrigerant discharge pressure of the compressor 11 with respect to the change in the amount of the refrigerant sealed in the cycle. Value (fine two-dot chain line), actual measured value of compressor 11 suction refrigerant pressure (thin one-dot chain line), circulating refrigerant flow rate Gr (thin solid line), and actual measured value of superheat degree of refrigerant on outlet side of evaporator 14 (dotted line). It is a graph which shows a change. In addition, the horizontal axis of FIG. 6 has shown the ratio of the refrigerant | coolant enclosure amount with respect to the regular enclosure amount.

  Here, in a general refrigeration cycle apparatus applied to a vehicle air conditioner, in consideration of refrigerant leakage that occurs over time, a value larger than the amount of refrigerant filled that the refrigeration cycle apparatus can properly exhibit cooling capacity is set. It is the regular enclosed amount. For example, in this embodiment, as shown in FIG. 6, even when the amount of sealing is 70% of the normal amount of sealing, the cooling capacity can be exhibited. Therefore, in this embodiment, the refrigerant shortage state is about 70% or less with respect to the regular enclosed amount.

  As shown in FIG. 6, when the refrigerant flowing into the evaporator 14 is 60% to 70% with respect to the normal enclosed amount, that is, the refrigerant flowing into the evaporator 14 is in a gas-liquid two-phase state. In addition, in the refrigerant shortage state in which the refrigerant is slightly short, the actually measured value of the heat exchange fin temperature Tef1 is rapidly lower than the estimated refrigerant evaporation temperature Tef2.

  This is because the refrigerant in the refrigeration cycle device has begun to run short, and the required amount of refrigerant in the cycle cannot be secured, and the refrigerant density in the cycle is reduced. This is to make a transition to (the one with the lower pressure).

  On the other hand, since the evaporator 14 is in a refrigerant shortage state, the vapor phase refrigerant of the evaporator 14 outlet side refrigerant is heated by the blown air blown from the blower fan 14a, and the degree of superheat of the evaporator 14 outlet side refrigerant. Begins to rise. For this reason, Tef1, which is the detected value of the heat exchange fin temperature in the vicinity of the evaporator 14 refrigerant inlet, becomes lower than the temperature of the refrigerant flowing out of the evaporator 14.

  For this reason, the enthalpy difference Ie of the above-mentioned formula F2 becomes smaller than the actual enthalpy difference, and the refrigerant side cooling capacity Qer calculated in the control step S6 becomes smaller than the actual value. Therefore, in the refrigerant shortage state in which the refrigerant is slightly insufficient, as shown in FIG. 7, the balance point where the refrigerant side cooling capacity Qer = air side cooling capacity Qea is also higher than the actual balance point, and the estimated refrigerant The evaporation temperature Tef2 is estimated to be higher than the actual refrigerant evaporation temperature.

  Furthermore, when the refrigerant flowing into the evaporator 14 is less than about 60% of the normal amount, ie, the refrigerant flowing into the evaporator 14 is almost in a gas phase, the refrigerant is largely insufficient. In this case, since the refrigerant hardly exhibits an endothermic effect in the evaporator 14, the difference between the suction side air temperature Tein and the heat exchange fin temperature Tef1 is reduced.

  For this reason, (Tein-Tef1) of the above-mentioned formula F3 becomes small, and the air side cooling capacity Qea calculated in control step S7 becomes smaller than the actual value. Therefore, in the refrigerant shortage state in which the refrigerant is largely insufficient, as shown in FIG. 8, the balance point where the refrigerant side cooling capacity Qer = air side cooling capacity Qea is also lower than the actual balance point, and the estimated refrigerant The evaporation temperature Tef2 is estimated to be lower than the actual refrigerant evaporation temperature.

  Therefore, in the present embodiment, in the control step S9, it is determined whether or not the absolute value of the difference between the estimated refrigerant evaporation temperature Tef2 and the heat exchange fin temperature Tef1 is equal to or greater than a predetermined reference difference KTef. Thus, it can be reliably determined that the refrigerant is in a shortage state. Furthermore, since the level of the heat exchange fin temperature Tef1 and the estimated refrigerant evaporation temperature Tef2 is compared in the control step S11, it is possible to accurately determine the degree of the refrigerant shortage state.

  In the present embodiment, the reference difference KTef used in the control step S9 is set so that the heat exchange fin temperature Tef1 is lower than the estimated refrigerant evaporation temperature Tef2, that is, even when the refrigerant is slightly insufficient. The value is determined so that it can be determined. Therefore, the degree of the refrigerant shortage state can be reliably and accurately determined.

  Specifically, in the present embodiment, as shown in FIG. 6, the reference difference KTef is set to 5 ° C. on the basis of the case where the refrigerant filling amount is reduced to about 68%. When the reference difference KTef is reduced to about 65%, it can be determined that the refrigerant is insufficient even if the reference difference KTef is about 10 ° C.

  According to the study by the present inventors, this reference difference KTef is obtained when the thermistor attached to the heat exchange fin of the evaporator 14 is employed as the blowout air temperature sensor 25 as in the present embodiment. It has also been found desirable to vary depending on the mounting position of the evaporator 14. This will be described with reference to FIG.

  FIG. 9 is a graph corresponding to FIG. 6, and shows a heat exchange fin temperature Tef <b> 1 (thick solid line) when a thermistor as the blowout air temperature sensor 25 is attached to a heat exchange fin near the refrigerant inlet of the evaporator 14. ) (Similar to FIG. 6), and attached to a heat exchange fin located at a substantially intermediate position of the refrigerant flow path of the evaporator 14 (substantially intermediate position between the evaporator 14 refrigerant inlet and the refrigerant outlet). This is a comparison of changes in heat exchange fin temperature Tef1 (thick two-dot chain line).

  9, for the sake of clarity of illustration, compared to FIG. 6, the measured value of the compressor 11 discharge refrigerant pressure, the measured value of the compressor 11 suction refrigerant pressure, the circulating refrigerant flow rate Gr (thin solid line), and The actual measurement value of the superheat degree of the evaporator 14 outlet side refrigerant is omitted.

  As shown in FIG. 9, when the thermistor serving as the blowout air temperature sensor 25 is separated from the vicinity of the refrigerant inlet and attached to the heat exchange fin located substantially in the middle of the refrigerant flow path of the evaporator 14, the refrigerant is slightly insufficient. In this case, the degree of decrease in the actual measurement value of the heat exchange fin temperature Tef1 is reduced, and the start of the temperature increase of the actual measurement value of the heat exchange fin temperature Tef1 accompanying the decrease in the refrigerant filling amount is accelerated.

  For this reason, when the thermistor is attached to the heat exchange fin located at a substantially intermediate position of the refrigerant flow path of the evaporator 14, the refrigerant shortage determination means (step S9) is used in comparison with the case where the thermistor is attached to the heat exchange fin near the refrigerant inlet. Thus, it becomes difficult to determine the refrigerant shortage state in which the refrigerant is slightly short. Therefore, it is desirable that the thermistor as the blowout air temperature sensor 25 is attached near the refrigerant inlet of the evaporator 14 rather than near the refrigerant outlet of the evaporator 14.

  For the convenience of mounting the thermistor as the blowout side air temperature sensor 25, when it is attached to the substantially middle position of the refrigerant flow path of the evaporator 14, specifically, the case where the refrigerant filling amount is reduced to about 68% is a standard. , The reference difference Ktef is about 3 ° C., and the reference difference Ktef is about 5 ° C. when the refrigerant filling amount is reduced to about 65%.

  Furthermore, in this embodiment, when it is detected in the control step S9 (refrigerant shortage determination means) that the refrigerant is in a shortage state, the warning light is turned on in step S10 regardless of the degree. Therefore, the user can be made aware of the refrigerant shortage state.

  Moreover, if it is determined in step S11 that the refrigerant is largely insufficient, the compressor 11 is stopped in step S12, so that the compressor 11 is protected by avoiding insufficient lubrication of the compressor 11. Can be planned.

  On the other hand, if it is determined in step S11 that the refrigerant is slightly insufficient, the refrigerant discharge capacity of the compressor 11 is not reduced, so that the refrigeration cycle is performed while allowing the user to recognize that the refrigerant is in an insufficient state. The apparatus can continuously exhibit the cooling capacity.

(Second Embodiment)
In the first embodiment described above, the warning lamp 34 is turned on when it is determined that the refrigerant is in a shortage state, and the compressor 11 is stopped only when the refrigerant is largely insufficient. As described above, in the present embodiment, as shown in the flowchart of FIG. 10, when it is determined that the refrigerant is in a shortage state, the warning lamp 34 is turned on and the compressor 11 is stopped.

  Specifically, in the present embodiment, the control step S11 is abolished and the control step S12 for stopping the compressor 11 is executed after the control step S10 with respect to the flowchart of FIG. 3 of the first embodiment. Other configurations and controls are the same as those in the first embodiment. Therefore, in this embodiment, when it is determined in the control step S9 that the refrigerant is in a shortage state, the compressor 11 can be reliably protected.

  Further, in the present embodiment, the control step S12 may be abolished and the warning lamp 34 may be turned on when it is determined that the refrigerant is in a shortage state.

(Other embodiments)
The present invention is not limited to the above-described embodiment, and can be variously modified as follows.

  (1) In each of the above-described embodiments, a variable displacement compressor is employed as the compressor 11, and the flow rate detection circuit 20a as the flow rate detection means compresses the physical quantity having a correlation with the circulating refrigerant flow rate circulating in the cycle. Although the example which detected the control current Ic output to the capacity | capacitance control valve 11a of the machine 11 was demonstrated, a flow volume detection means is not limited to this.

  For example, a flow rate sensor that directly detects the flow rate of the circulating refrigerant circulating in the cycle may be employed as the flow rate detection means. Specifically, a mass flow sensor such as a differential pressure type flow sensor or a hot wire type flow sensor can be employed.

  Further, when an electric compressor is employed as the compressor 11, a rotation speed sensor that detects the rotation speed of the electric compressor can be employed as the flow rate detection means. Furthermore, you may employ | adopt the sensor which detects the control signal (control voltage, control frequency, etc.) output to the electric motor of an electric compressor.

  (2) In each of the above-described embodiments, the blower amount detection circuit 20b as the blower amount detection means is output to the electric motor of the blower fan 14a as a physical quantity having a correlation with the blown air amount blown from the blower fan 14a. Although the example which detected the control voltage BLV was demonstrated, the ventilation volume detection means is not limited to this. For example, a flow rate sensor that directly detects the amount of air blown to the evaporator 14 may be employed as the air flow rate detecting means.

  (3) An internal heat exchanger for exchanging heat between the refrigerant on the outlet side of the radiator 12 and the refrigerant on the suction side of the compressor 11 may be provided for the refrigeration cycle apparatus 10 of each of the embodiments described above. Thereby, the enthalpy difference (refrigeration capacity) between the inlet side refrigerant and the outlet side refrigerant in the evaporator 14 can be increased.

  In the case where an internal heat exchanger is provided, the amount of increase in the enthalpy difference due to the internal heat exchanger may be added to the enthalpy difference Ie in Formula F2 when calculating the refrigerant side cooling capacity Qer in control step S6. . Further, the heat exchange amount equivalent amount in the internal heat exchanger can be calculated from the heat exchange fin temperature Tef1, the circulating refrigerant flow rate Gr, the heat exchange efficiency φ of the internal heat exchanger, and the like.

  (4) In each of the above-described embodiments, an example in which the operation of the compressor 11 is substantially stopped in the control step S12 when it is determined that the refrigerant is in a shortage state has been described. The compressor 11 may be operated continuously by reducing the refrigerant discharge capacity to such an extent that the durable life of the compressor 11 is not deteriorated. Thereby, although the cooling capacity of the refrigeration cycle apparatus is lowered, the refrigeration cycle apparatus can continuously exhibit the cooling capacity.

  (5) In the above-described embodiment, a warning light is used as the warning means. However, for example, an acoustic device that issues a warning by sound, a vibration device that generates a warning by vibration, or the like may be used.

  (6) In the above-described embodiment, an example in which the refrigeration cycle apparatus 10 of the present invention is applied to a vehicle air conditioner has been described, but the application of the present invention is not limited to this. For example, the present invention may be applied to a commercial refrigeration apparatus, a household refrigerator, and the like. Further, the refrigerant is not limited to carbon dioxide, and a chlorofluorocarbon refrigerant or an HC refrigerant may be employed.

  (7) In the above-described embodiment, the radiator 12 is an outdoor heat exchanger that exchanges heat between the refrigerant and the outside air, and the evaporator 14 is an indoor heat exchanger that is applied for cooling the vehicle interior. The present invention is applied to a heat pump cycle in which the evaporator 14 is configured as an outdoor heat exchanger that absorbs heat from a heat source such as outside air, and the radiator 12 is configured as an indoor heat exchanger that heats a heated fluid such as air or water. May be.

It is a whole lineblock diagram of the refrigerating cycle device of a 1st embodiment. It is a characteristic view which shows the relationship between the control current of 1st Embodiment, and a circulating refrigerant flow rate. It is a flowchart which shows control of the vehicle air conditioner of 1st Embodiment. It is a Mollier diagram which shows the state of the refrigerant | coolant of the refrigerating-cycle apparatus of 1st Embodiment. It is a graph which shows the change of the refrigerant | coolant side cooling capability and air side cooling capability of 1st Embodiment. It is a graph which shows changes, such as a heat exchange fin temperature and estimated refrigerant | coolant evaporation temperature, with respect to the change of the refrigerant | coolant enclosure amount of 1st Embodiment. It is a graph which shows the change of the refrigerant | coolant side cooling capability in the refrigerant | coolant insufficient state of 1st Embodiment, and the air side cooling capability. It is a graph which shows the change of the refrigerant | coolant side cooling capability and the air side cooling capability in another refrigerant | coolant insufficient state of 1st Embodiment. It is a graph which shows the change of the heat exchange fin temperature by the blowing side air temperature sensor attachment position of 1st Embodiment. It is a flowchart which shows control of the vehicle air conditioner of 2nd Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Compressor 12 Radiator 13 Pressure control valve 14 Evaporator 14a Air blower fan 20a Flow rate detection circuit 20b Air flow rate detection circuit 21 Outside air temperature sensor 24 Suction side air temperature sensor 25 Outlet air temperature sensor 34 Warning light S6 Refrigerant side capacity calculation means S7 Air side capacity calculation means S8 Evaporation temperature estimation means S9 Refrigerant shortage determination means Qer Refrigerant side cooling capacity Qea Air side cooling capacity Tef1 Heat exchange fin temperature Tef2 Estimated refrigerant evaporation temperature Tein Suction side air temperature KTef Reference difference

Claims (10)

A compressor (11) for compressing and discharging the refrigerant;
A radiator (12) for radiating the refrigerant discharged from the compressor (11);
Decompression means (13) for decompressing the refrigerant radiated by the radiator (12);
An evaporator (14) for evaporating the refrigerant decompressed by the decompression means (13);
A blower (14a) for blowing air to exchange heat with the refrigerant toward the evaporator (14);
A flow rate detection means (20a) for detecting a physical quantity having a correlation with a circulating refrigerant flow rate circulating in the cycle;
An outside air temperature detecting means (21) for detecting the temperature of the outdoor air;
A blowing amount detecting means (20b) for detecting a physical quantity having a correlation with the blowing air amount blown from the blower (14a);
Suction side temperature detection means (24) for detecting the temperature of air blown to the evaporator (14);
Blowing side temperature detecting means (25) for detecting the temperature of the air blown out from the evaporator (14);
Refrigerant-side cooling capacity (Qer) using at least the detected circulating refrigerant flow rate (Gr) detected by the flow rate detection means (20a) and the detected outside air temperature (Tam) detected by the outside air temperature detection means (21). Refrigerant side capacity calculating means (S6) for calculating
At least the detected blown air amount (Ga) detected by the blown amount detection means (20b), the detected suction side air temperature (Tein) detected by the suction side temperature detection means (24), and the blowout side temperature detection Air-side capacity calculating means (S7) for calculating the air-side cooling capacity (Qea) using the detected outlet-side air temperature (Tef1) detected by the means (25);
Evaporation temperature estimation means (S8) that uses the refrigerant evaporating temperature (Tef2) as the refrigerant evaporating temperature (Tef2) of the evaporator (14) in which the air-side cooling capacity (Qea) and the refrigerant-side cooling capacity (Qer) are equal;
A refrigerant shortage determining means (S9) for determining that the refrigerant circulating in the cycle is short of refrigerant.
When the absolute value of the difference between the estimated refrigerant evaporation temperature (Tef2) and the detected outlet side air temperature (Tef1) is equal to or greater than a predetermined reference difference (KTef), the refrigerant shortage determining means (S9) A refrigeration cycle apparatus that determines that the refrigerant is in a shortage state. Discharge capacity changing means (11a) for changing the refrigerant discharge capacity of the compressor (11);
A discharge capacity control means (20c) for controlling the operation of the discharge capacity changing means (11a);
Warning means (34) for warning the user when the refrigerant shortage determining means (S9) determines that the refrigerant is in a shortage state,
The discharge capacity control means (20c) is when it is determined that the refrigerant is in a shortage state, and when the detected outlet air temperature (Tef1) is higher than the estimated refrigerant evaporation temperature (Tef2), The refrigeration cycle apparatus according to claim 1, wherein the refrigerant discharge capacity is reduced. Discharge capacity changing means (11a) for changing the refrigerant discharge capacity of the compressor (11);
A discharge capacity control means (20c) for controlling the operation of the discharge capacity changing means (11a),
The refrigeration cycle apparatus according to claim 1, wherein the discharge capacity control means (20c) reduces the refrigerant discharge capacity when it is determined that the refrigerant is in a shortage state. The compressor is a variable capacity compressor (11) configured to be capable of changing the discharge capacity,
The discharge capacity changing means is a capacity control valve (11a) for changing the discharge capacity,
The refrigeration cycle apparatus according to claim 2 or 3, wherein the flow rate detection means detects a control signal (Ic) output from the discharge capacity control means (20c) to the capacity control valve (11a). .   The refrigeration cycle apparatus according to claim 1, further comprising warning means (34) for warning the user when the refrigerant shortage determining means (S9) determines that the refrigerant is in a shortage state.   The refrigerant side capacity calculating means (S6) further calculates a refrigerant side cooling capacity (Qer) by using the detected blowout side air temperature (Tef1). The refrigeration cycle apparatus described in 1.   The air side capacity calculating means (S7) further calculates the air side cooling capacity (Qer) using at least one of the specific heat of air (Ca) and the heat exchange efficiency (φe) of the evaporator (14). The refrigeration cycle apparatus according to claim 1, wherein the refrigeration cycle apparatus is calculated.   The reference difference (KTef) can determine that the refrigerant shortage determination means (S9) is in a refrigerant shortage state when the detected blow-out air temperature (Tef1) is lower than the estimated refrigerant evaporation temperature (Tef2). The refrigeration cycle apparatus according to any one of claims 1 to 7, wherein the refrigeration cycle apparatus is set to a value.   The refrigeration cycle apparatus according to any one of claims 1 to 8, wherein the compressor (11) raises the pressure of the refrigerant until a critical pressure or higher is reached.   The refrigeration cycle apparatus according to any one of claims 1 to 9, wherein the refrigerant is carbon dioxide.

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