JP2009097772A - Refrigerating cycle device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To sufficiently improve responsiveness when bringing the actual refrigerant evaporation temperature of an evaporator closer to a target refrigerant target temperature in a refrigerating cycle device. <P>SOLUTION: A flow sensor is provided for detecting a refrigerant flow rate Gr delivered from a compressor, and a refrigerant side cooling capacity Qer is accurately calculated by using the refrigerant flow rate Gr, and enthalpy difference between an evaporator inlet side refrigerant and an outlet side refrigerant. A balance point of the refrigerant side cooling capacity Qer and an air side cooling capacity Qea is used as an estimated refrigerant evaporation temperature TL, and feedback control of a refrigerant delivery performance of the compressor is carried out such that the TL is brought closer to the target evaporation temperature TEO determined such that a cooling object space can be properly cooled. By this, the responsiveness when bringing the actual refrigerant evaporation temperature Te of the evaporator closer to the target refrigerant evaporation temperature TEO can be improved. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a refrigeration cycle apparatus including a compressor configured to be able to change refrigerant discharge capacity.

  DESCRIPTION OF RELATED ART Conventionally, the refrigerating-cycle apparatus provided with the compressor comprised so that a refrigerant | coolant discharge capability was changeable like a variable capacity type compressor and an electric compressor was known. For example, Patent Document 1 discloses a refrigeration cycle apparatus that employs a variable displacement compressor configured to be capable of changing a discharge capacity as a compressor.

  In the refrigeration cycle apparatus of Patent Document 1, the discharge of the compressor is based on the deviation between the actual refrigerant evaporation temperature Te of the evaporator and the target refrigerant evaporation temperature TEO determined so that the space to be cooled can be appropriately cooled. By performing feedback control of the capacity (refrigerant discharge capacity), the refrigerant evaporation temperature Te is brought close to the target refrigerant evaporation temperature TEO.

  Furthermore, in Patent Document 2, when the target refrigerant evaporation temperature TEO is applied to a vehicle air conditioner, the target refrigerant evaporation temperature TEO before change, the outside air temperature Tam, the vehicle speed, and the evaporator are blown. A refrigeration cycle apparatus that feedforward-controls the discharge capacity (refrigerant discharge capacity) of a compressor based on the amount of blown air is disclosed.

In the refrigeration cycle apparatus of Patent Document 2, this feedforward control is intended to improve the response when bringing the actual refrigerant evaporation temperature Te of the evaporator closer to the target refrigerant evaporation temperature TEO.
JP 2002-283840 A Japanese Patent Laid-Open No. 2005-193749

  Incidentally, the refrigerant evaporating temperature Te of the evaporator is determined according to the refrigerant evaporating pressure at the balance point (a point where the air side cooling capacity Qer and the refrigerant side cooling capacity Qer are equal). Here, the air-side cooling capacity Qea means the total amount of heat that air radiates to the refrigerant in the evaporator, and the refrigerant-side cooling capacity Qer means the total amount of heat that the refrigerant absorbs from the air in the evaporator.

  Therefore, the air-side cooling capacity Qea is a product of the temperature difference between the air temperature blown to the evaporator (evaporator intake air temperature) and the refrigerant evaporation temperature in the evaporator, and the amount of blown air blown to the evaporator. Determined by. On the other hand, the refrigerant side cooling capacity Qer is determined by the product of the enthalpy difference between the enthalpy of the evaporator outlet refrigerant and the enthalpy of the evaporator inlet refrigerant, and the refrigerant flow rate Gr circulating in the cycle.

  However, in the feedforward control of Cited Document 2, the target refrigerant evaporation temperature TEO, the outside air temperature Tam, the vehicle speed, and the amount of air blown to the evaporator before the change are considered, but the refrigerant flow rate circulating in the cycle Gr is not considered. Therefore, the refrigerant side cooling capacity Qer cannot be accurately calculated.

  Therefore, in Cited Document 2, it is not possible to accurately estimate the refrigerant evaporation temperature when the target refrigerant evaporation temperature TEO is changed. As a result, even if the feedforward control is performed, it is not possible to sufficiently obtain the effect of improving the response when bringing the actual refrigerant evaporation temperature Te of the evaporator closer to the target refrigerant evaporation temperature TEO. Furthermore, the refrigerant evaporation temperature Te of the evaporator may be lowered more than necessary, and the evaporator may be frosted.

  In view of the above points, the present invention provides a refrigeration cycle apparatus including a compressor configured to be able to change the refrigerant discharge capacity, and has sufficient responsiveness when bringing the actual refrigerant evaporation temperature of the evaporator closer to the target refrigerant evaporation temperature. The purpose is to improve.

To achieve the above object, the present invention includes a compressor (11, 11 ′) that compresses and discharges a refrigerant, and a radiator (12) that radiates heat from the refrigerant discharged from the compressor (11, 11 ′). The decompression means (13) for decompressing and expanding the refrigerant radiated by the radiator (12), and evaporating the refrigerant decompressed and expanded by the decompression means (13) Discharge for controlling the operation of the evaporator (14) for cooling, the discharge capacity changing means (11a, 11b) for changing the refrigerant discharge capacity of the compressor (11, 11 '), and the discharge capacity changing means (11a, 11b) The capacity control means (20a), the flow rate detection means (26) for detecting a physical quantity correlated with the refrigerant flow rate (Gr) circulating in the cycle, and the target refrigerant evaporation temperature (TEO) in the evaporator (14) are determined. Target evaporation temperature determining means (S5 Load variation determining means (S8) for determining that the air side cooling load has changed, refrigerant side capacity calculating means (S6) for calculating the refrigerant side cooling capacity (Qer), and air side cooling capacity (Qea) ) And 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 to the estimated refrigerant evaporation temperature (TL). Evaporating temperature estimating means (S91)
The refrigerant side capacity calculating means (S6) calculates the refrigerant side cooling capacity (Qer) using at least the detection value (Gr) of the flow rate detecting means (26), and the discharge capacity control means (20a) is an air side cooling load. When the fluctuation of the engine is detected, the refrigeration cycle apparatus performs feedforward control of the operation of the discharge capacity changing means (11a, 11b) so that the estimated refrigerant evaporation temperature (TL) approaches the target refrigerant evaporation temperature (TEO). And

  According to this, since the refrigerant side capacity calculation means (S6) calculates the refrigerant side cooling capacity (Qer) using at least the detection value (Gr) of the flow rate detection means (26), for example, the target refrigerant before the change Calculating the refrigerant side cooling capacity (Qer) with high accuracy compared to the calculation based only on the evaporation temperature (TEO), the outside air temperature (Tam), the vehicle speed, and the amount of air blown to the evaporator (BLV). Can do.

  Therefore, when the air-side cooling load fluctuates, it is possible to improve the estimation accuracy of the estimated refrigerant evaporation temperature (TL) at the balance point between the air-side cooling capacity (Qea) and the refrigerant-side cooling capacity (Qer).

  Further, the discharge capacity control means (20a) feedforward-controls the operation of the discharge capacity change means (11a, 11b) so that the estimated refrigerant evaporation temperature (TL) with high accuracy approaches the target evaporation temperature (TEO). Therefore, it is possible to sufficiently improve the responsiveness when bringing the actual refrigerant evaporation temperature (Te) of the evaporator closer to the target refrigerant evaporation temperature (TEO).

  Further, in the refrigeration cycle apparatus having the above characteristics, specifically, the load variation determination means (S8) may determine the variation of the air-side cooling load when the amount of the blown air is changed. Good.

  Moreover, in the refrigeration cycle apparatus having the above-described features, the blown air includes at least one of the air in the cooling target space and the air outside the cooling target space, and further, in the cooling target space in the blown air. The air volume ratio changing means (16c) for changing the air volume ratio between the air volume and the air volume outside the space to be cooled is provided, and the load fluctuation determining means (S8) is configured so that the air volume ratio changing means (16c) changes the air volume ratio. It may be determined that the air-side cooling load has fluctuated.

  When the air volume ratio changing means (16c) changes the air volume ratio, it means that the temperature of the air blown to the evaporator (14) changes, so that the fluctuation of the air-side cooling load can be detected.

  The refrigeration cycle apparatus having the above-described features further includes target temperature setting means (33) for setting the target temperature (Tset) of the space to be cooled, and the load fluctuation determination means (S8) has a target temperature (Tset) of When the change is made, the variation of the air-side cooling load is determined.

  When the target temperature (Tset) of the space to be cooled is changed, it means a change in the temperature of the air blown from the evaporator (14), so that a change in the air-side cooling load can be detected.

  In the refrigeration cycle apparatus having the above-described characteristics, the air-side capacity calculating means (S7) includes a physical quantity (Tam, Tr) correlated with the intake air temperature (Ta) of the blown air on the evaporator (14) suction side, The air-side cooling capacity (Qea) is determined by using at least one of a physical quantity (BLV) correlated with the amount of blown air of air and a physical quantity (Tef) correlated with the refrigerant evaporation temperature in the evaporator (14). You may come to calculate.

  As described above, the air-side cooling capacity (Qea) depends on the temperature difference between the temperature of the air sent to the evaporator (14) (the intake air temperature of the evaporator) and the refrigerant evaporation temperature in the evaporator, and the air sent to the evaporator. Determined by the product of the amount of air blown. Accordingly, at least one of physical quantities (Tam, Tr) correlated with the intake air temperature (Ta), physical quantities correlated with the blown air quantity (BLV), and physical quantities (Tef) correlated with the refrigerant evaporation temperature. Can be used to calculate a more accurate air-side cooling capacity (Qea).

  In the refrigeration cycle apparatus having the above characteristics, the refrigerant side capacity calculating means (S6) further includes an outlet side specific enthalpy (Ieo) of the evaporator (14) outlet side refrigerant and an inlet side refrigerant inlet of the evaporator (14). The refrigerant side cooling capacity (Qer) may be calculated using at least one of physical quantities (Tam, Tef) correlated with the enthalpy difference (Ie) from the side specific enthalpy (Iei).

  As described above, the refrigerant side cooling capacity (Qer) is the difference in enthalpy between the outlet side specific enthalpy (Ieo) of the evaporator (14) outlet side refrigerant and the inlet side specific enthalpy (Iei) of the evaporator (14) inlet side refrigerant. (Ie) and the product of the refrigerant flow rate (Gr) circulating in the cycle. Therefore, in addition to the detection value (Gr) of the flow rate detection means (26) described above, the physical quantity (Tam, Tef) correlated with the enthalpy difference (Ie) is used, so that more accurate refrigerant side cooling capacity ( Qer) can be calculated.

    Further, in the refrigeration cycle apparatus having the above-described features, specifically, the decompression means controls the valve so that the high-pressure side refrigerant pressure approaches the target high pressure determined according to the high-pressure side refrigerant temperature downstream of the radiator (12). It may be a pressure control valve (13) whose opening is adjusted.

  Here, since the high-pressure side refrigerant temperature downstream of the radiator (12) is generally a value substantially equal to the outside air temperature (Tam), in the refrigeration cycle apparatus employing the pressure control valve (13), As the temperature (Tam) changes, the high-pressure side refrigerant pressure changes. Therefore, if the pressure control valve (13) is employed as the pressure reducing means, the inlet side ratio of the above-described evaporator (14) inlet side refrigerant based on the outside air temperature (Tam) as described in the embodiment described later. Enthalpy (Iei) can be estimated.

  Further, the outlet side specific enthalpy (Ieo) of the evaporator (14) outlet side refrigerant can be estimated based on the heat exchange fin temperature (Tef) of the evaporator (14).

  In the refrigeration cycle apparatus having the above-described characteristics, specifically, the compressor is a variable displacement compressor (11) configured to be capable of changing the discharge capacity, and the discharge capacity changing means changes the discharge capacity. It is a capacity control valve (11a), and the flow rate detecting means may comprise a flow rate sensor (26) for detecting the refrigerant flow rate (Gr) circulating in the cycle.

  In the refrigeration cycle apparatus having the above-described characteristics, specifically, the compressor is a fixed capacity compressor (11 ′) having a fixed discharge capacity, and the discharge capacity changing means is a fixed capacity compressor (11). ') Is an electric motor (11b) for rotationally driving, and the flow rate detecting means may include a rotational speed detecting means (27) for detecting the rotational speed of the fixed displacement compressor (11'). .

  Furthermore, at least a part of the flow rate detection means (26, 27) may be configured integrally with the compressor (11, 11 '). Thereby, size reduction of a flow volume detection means (26, 27) and a compressor (11, 11 ') can be achieved.

  In the refrigeration cycle apparatus having the above-described characteristics, the compressor (11, 11 ') may be configured to increase the pressure of the refrigerant until it reaches a critical pressure or higher. 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).

  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. . Further, in the present embodiment, a 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 controller 20 described later is adopted as the compressor 11. .

  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 (Pd-Ps) between the suction refrigerant pressure Ps and the discharge refrigerant pressure Pd of the compressor 11, and an electromagnetic force that opposes the force due to the differential pressure. And an electromagnetic mechanism for generating a swash plate chamber, and adjusts the valve opening (ratio between the suction refrigerant and the discharge refrigerant) by changing the balance between the force due to the differential pressure and the electromagnetic force, thereby changing 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.

  Since the discharge flow rate Gr of the compressor 11 increases and decreases according to the increase and decrease of the discharge capacity, the electromagnetic capacity control valve 11a of the present embodiment constitutes a discharge capacity changing unit. Furthermore, the target value (target flow rate) of the discharge refrigerant flow rate of the compressor 11 is determined by the control current Ic.

  In the present embodiment, the relationship between the control current Ic and the discharge flow rate Gr of the compressor 11 is as shown in the characteristic diagram of FIG. 2, as the control current Ic increases, the discharge flow rate Gr of the compressor 11. Has come to increase.

  In addition, the output of the control current Ic is usually a method of changing by duty control due to the configuration of the current control circuit, but the value of the control current Ic is directly and continuously independent of duty control. It may be changed to (analog). Thus, by adjusting the control current Ic, the compressor 11 can continuously change the discharge capacity in the range of approximately 0% to 100%.

  In the compressor 11 of the present embodiment, the discharge capacity can be reduced to about 0%. Therefore, as described above, the compressor 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.

  As shown in FIG. 1, 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.

  As described above, since the refrigeration cycle apparatus 10 of the present embodiment constitutes a supercritical refrigeration cycle, the refrigerant passing through the radiator 12 dissipates 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 decompresses and expands the high-pressure refrigerant flowing out from the internal heat exchanger 13, and the valve opening (throttle opening) is adjusted by a mechanical mechanism so that the high-pressure side refrigerant pressure becomes the target high pressure. It is comprised so that.

  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. A pressure control valve 13 having such a high-pressure control function is known in Japanese Patent Application Laid-Open No. 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 14 a is an electric blower in which the rotation speed (the amount of blown air) is controlled by a control voltage output from the air conditioning control device 20.

  In the present embodiment, a heat exchanger having a well-known fin-and-tube structure is employed as the evaporator 14. Furthermore, this evaporator 14 is arrange | positioned in the case 15 which forms the air passage of vehicle interior blowing air in the indoor air conditioning unit of a vehicle air conditioner.

  At the most upstream part of the air flow of the case 15, an inside / outside air switching box 16 for switching and introducing the inside air (vehicle compartment air) and the outside air (vehicle compartment outside air) is provided. The inside / outside air switching box 16 is formed with an inside air introduction port 16 a for introducing inside air into the case 15 and an outside air introduction port 16 b for introducing outside air.

  Further, an inside / outside air switching door 16c that opens and closes the inside air introduction port 16a and the outside air introduction port 16b is rotatably disposed inside the inside / outside air switching box 16. The inside / outside air switching door constitutes air volume ratio changing means for continuously adjusting the opening areas of the inside air introduction port 16a and the outside air introduction port 16b to change the air volume ratio between the air volume of the inside air and the air volume of the outside air. It is driven by a servo motor 16d.

  Further, on the downstream side of the air flow of the evaporator 14 inside the case 15, a heater core 17 that reheats the cold air cooled by the evaporator 14 and an air mix that adjusts the air volume ratio of the cold air that passes through the heater core 17. A door 18 is arranged. The heater core 17 is a heating unit that reheats the cold air using the coolant of the vehicle running engine as a heat source.

  The air mix door 18 constitutes temperature adjusting means for adjusting the temperature of the conditioned air blown into the vehicle interior, and is driven by a servo motor 18a. The operation of the servo motor 16d of the inside / outside air switching door 16c and the servo motor 18a of the air mix door 18 is controlled by a control signal output from the air conditioning control device 20.

  Further, an air outlet (not shown) that blows out the blown air whose temperature is adjusted into the vehicle interior, which is the space to be cooled, is disposed at the most downstream portion of the air flow of the case 15. Specifically, the air outlet includes a face air outlet that blows air-conditioned air toward the upper body of the passenger in the passenger compartment, a foot air outlet that blows air-conditioned air toward the feet of the passenger, and an inner surface of the front window glass of the vehicle. A defroster outlet for blowing air conditioned air is provided.

  An accumulator 19 is connected to the outlet side of the evaporator 14. The accumulator 19 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 refrigerant in the cycle. The accumulator 19 is provided with a gas phase refrigerant outlet through which the gas phase refrigerant flows out, and the 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 various electric actuators 11a, 12a, 14a, 16d, 18a 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 the hardware and software to be controlled is the discharge capacity control means 20a.

  An air conditioning sensor group 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. The air conditioning sensor group 21 to 26 is provided with a detection signal and an operation panel 30. The operation signals of the various operation switches 31 to 33 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 an evaporator. 14, an evaporator temperature sensor 24 that detects the heat exchange fin temperature Tef, a high-pressure sensor 25 that detects the discharge refrigerant pressure Pd discharged from the compressor 11, and a flow rate detection that detects the refrigerant flow rate Gr discharged from the compressor 11. A flow sensor 26 as a means is provided.

  In addition, the evaporator temperature sensor 24 of this embodiment is for detecting the temperature of the blown air blown out from the evaporator 14. Therefore, instead of the evaporator temperature sensor 24, a blown air temperature sensor, which is a blown air temperature detecting means for directly detecting the temperature of the air blown from the evaporator 14, may be used.

  The flow sensor 26 detects a refrigerant flow rate circulating in the cycle, that is, a discharge flow rate Gr of the compressor 11. The flow sensor 26 is provided in a housing that forms a refrigerant discharge side passage of the compressor 11. That is, the flow sensor 26 is configured integrally with the compressor 11 so that the compressor 11 and the flow sensor 26 are downsized.

  Further, the flow sensor 26 has a throttle portion that allows a refrigerant circulating in the cycle to pass therethrough, a differential pressure detection portion that detects a pressure loss (differential pressure) in the throttle portion, and a temperature of the refrigerant on the downstream side of the throttle portion. And a temperature / pressure detection unit for detecting pressure, and a differential pressure type for detecting a refrigerant flow rate based on a detection value (differential pressure) of the differential pressure detection unit and a refrigerant density estimated from the detection value of the temperature / pressure detection unit It is constituted by a flow sensor.

  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 output side of the air-conditioning control device 20, an electromagnetic capacity control valve 11a of the compressor 11, an electric motor for the cooling fan 12a and the blower fan 14a, a servo motor 16d for driving the inside / outside air switching door 16c, and an air mix door 18 Are connected to an electric actuator such as a servo motor that drives an opening / closing door that opens and closes each outlet, and the operation of these devices is controlled by an output signal of the air conditioning controller 20.

  Next, the operation of this embodiment having the above configuration will be described with reference to FIGS. 3 and 4 are flowcharts showing the control processing 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 constant for correction.

  Next, in step S4, control states of various air conditioning control devices excluding the compressor 11 are determined. That is, among the various electric actuators connected to the output side of the air conditioning controller 20, the electric motor of the blower fan 14a, the servo motor 16d of the inside / outside air switching door 16c, the air mix door 18 excluding the electromagnetic capacity control valve 11a. The servo motor 18a, the control signal output to the servo motor of the open / close door that opens and closes each outlet are determined.

  As for the control signal (control voltage BLV) output to the electric motor of the blower fan 14a, the control signal stored in the air-conditioning control device 20 in advance is referred to based on the target blowing temperature TAO, and appropriate for the TAO. The air flow is determined to be the amount.

  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.

  For the control signal output to the servo motor of the inside / outside air switching door 16c, based on the target blowing temperature TAO, referring to a control map stored in advance in the air conditioning control device 20, an appropriate air passage according to TAO Decide to be.

  Specifically, the inside air mode is set when the inside air temperature Tr is higher than a predetermined temperature with respect to the set temperature Tset (at the time of cooling high load), and as the TAO rises from the low temperature side to the high temperature side, the all inside air mode → the inside / outside air Switch from mixed mode to all outside air mode.

  For the control signal output to the servo motor of the air mix door 18, the target opening degree SW of the air mix door 18 is calculated based on the detection signal of the evaporator temperature sensor 24 and the coolant temperature of the vehicle running engine. Then, the control signal is determined so that the opening degree of the air mix door 18 becomes the target opening degree SW.

  For the control signal output to the servo motor of the open / close door that opens and closes each outlet, the control signal stored in advance in the air-conditioning control device 20 is referred to based on the target outlet temperature TAO, and the control signal appropriate for the TAO is selected. Decide to open and close the outlet.

  Next, the target refrigerant | coolant evaporation temperature TEO in the evaporator 14 is determined in step S5. Specifically, based on the target blowing temperature TAO, the target refrigerant evaporation temperature TEO is determined with reference to a control map as shown in FIG. In the present embodiment, it is determined that TEO increases as TAO increases. Therefore, the control step S5 constitutes a target evaporation temperature determining means.

  Note that TEOmn shown in FIG. 5 is a lower limit value (margin) of the target refrigerant evaporation temperature TEO set to prevent frost formation on the evaporator 14, and is 3 ° C. in this embodiment. According to the study by the present inventors, it is desirable that 0.5 ° C. ≦ TEOmn ≦ 5 ° C. in a refrigeration cycle apparatus that employs carbon dioxide as a refrigerant and constitutes a supercritical refrigeration cycle. More preferably, it has been found that 1 ° C. ≦ TEOmn ≦ 3 ° C.

Next, in step S6, the refrigerant side cooling capacity Qer is calculated. Specifically, the refrigerant-side cooling capacity Qer is calculated by the following formula F2 based on the outside air temperature Tam detected by the outside air temperature sensor 21 and the refrigerant flow rate Gr detected by the flow rate sensor 26.
Qer = Gr × Ie (F2)
Note that 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. 6 is a Mollier diagram showing the state of the refrigerant during normal operation of the refrigeration cycle apparatus 10 of the present embodiment.

  A point Ro in FIG. 6 indicates the state of the refrigerant on the outlet side of the radiator 12. The refrigerant temperature at this point Ro is generally substantially equal to the outside air temperature Tam. Therefore, adjusting the high-pressure side refrigerant pressure to the target high pressure determined by the high-pressure side refrigerant temperature on the outlet side of the radiator 12 as in the pressure control valve 13 of the present embodiment is a target determined by the outside air temperature Tam. It means adjusting to high pressure.

  For this reason, the refrigerant state on the radiator outlet side can be estimated from the outside air temperature Tam, and the evaporator inlet side specific enthalpy Iei can be estimated.

  In addition, an accumulator 19 is connected to the outlet of the evaporator 14, and the amount of circulating refrigerant in the cycle is adjusted so that the state of the outlet of the evaporator becomes a saturated gas state. For this reason, the refrigerant state at the outlet of the evaporator 14 can be estimated from the physical quantity Tef correlated with the evaporator temperature, and at the same time, the specific enthalpy at the outlet of the evaporator 14 can be estimated.

  Therefore, the physical quantity (Tam) correlated with the specific enthalpy of the evaporator 14 inlet and the physical quantity (Tef) correlated with the specific enthalpy of the evaporator 14 outlet from the outlet specific enthalpy Ieo of the evaporator 14 outlet refrigerant and the evaporator 14 inlet. The inlet side specific enthalpy Iei of the side refrigerant can be estimated.

  Accordingly, in step S6, the enthalpy difference Ie is estimated with reference to the control map stored in advance based on the outside air temperature Tam, and the enthalpy difference Ie is further substituted into the above formula F2 to obtain the refrigerant side cooling capacity Qer. Is calculated. Therefore, the control step S6 in the present embodiment constitutes a refrigerant side capacity calculating means, and the outside air temperature Tam is a physical quantity correlated with the enthalpy difference Ie.

Next, in step S7, the air-side cooling capacity Qea is calculated. Specifically, the air-side cooling capacity Qea is determined by the inside air temperature Tr detected by the inside air temperature sensor 22, the outside air temperature Tam detected by the outside air temperature sensor 21, the estimated refrigerant evaporation temperature TL in the evaporator 14, and the air blowing. Based on the control voltage BLV output to the fan 14a, it is calculated by the following mathematical formula F3.
Qea = f (Ta, TL, BLV) (F3)
Note that Ta is the intake air temperature Ta that is blown to the evaporator 14 and sucked into the evaporator 14.

  The intake air temperature Ta is the inside air temperature Tr detected by the inside air temperature sensor 22 when the inside air is introduced from the inside / outside air switching box 16 described above, and is detected by the outside air temperature sensor 21 when the outside air is introduced. The outside temperature Tam. When the inside air and the outside air are introduced simultaneously, it is determined from Tr and Tam according to the air volume ratio. Therefore, the inside air temperature Tr and the outside air temperature Tam are physical quantities having a correlation with the suction air temperature Ta on the evaporator 14 suction side.

  Moreover, since the control voltage BLV is a value used for control of the rotation speed (blasting air amount) of the blower fan 14a, the blown air blown to the evaporator 14, that is, the blown air blown to the cooling target space. It is a physical quantity that correlates with the amount of blown air.

  In step S7, specifically, based on the control voltage BLV, the amount of blown air is determined with reference to a pre-stored control map, and the estimated refrigerant evaporation temperature TL is calculated from the intake air temperature Ta to this amount of blown air. Is multiplied by the control constant determined from the air specific heat and the evaporator 14 heat exchange efficiency, and the air-side cooling capacity Qea is calculated.

  Therefore, the control step S7 in the present embodiment constitutes an air side capacity calculating means. In step S7, the air-side cooling capacity Qea is calculated with the estimated evaporative refrigerant temperature TL as a variable.

  Next, in step S8, it is determined whether or not the air-side cooling load has changed. Specifically, in step S8, the control voltage BLV (the amount of air blown from the blower fan 14a) is changed by comparing the value of the control signal determined in step S4 with the currently output control signal. In other words, the air-side cooling load has changed when at least one of the change of the air volume ratio by the inside / outside air switching door 16c or the change of the set temperature Tset by the temperature setting switch 33 is detected. Is determined.

  Therefore, the control step S8 in the present embodiment constitutes a load fluctuation detecting means. When a change is detected in the air-side cooling load in step S8, the process proceeds to step S9, and the control current Ic output to the electromagnetic capacity control valve 11a of the compressor 11 is determined by feedforward control.

  On the other hand, if no change is detected in the air-side cooling load in step S8, the process proceeds to step S10, and the control current Ic output to the electromagnetic capacity control valve 11a of the compressor 11 without executing the feedforward control. Is determined by feedback control.

  The contents of the feedforward control in step S9 will be described based on the flowchart of FIG. First, in step S91, the estimated evaporative refrigerant temperature TL 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 TL will be described with reference to FIG. The horizontal axis in FIG. 7 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 S91, the refrigerant evaporation temperature that satisfies the following formula F4 is estimated as the estimated refrigerant evaporation temperature TL.
Qer = Qea (F4)
Therefore, the control step S91 in this embodiment constitutes an evaporating temperature estimating means.

Next, in step S92, the necessary refrigerant flow rate Grn necessary for the estimated refrigerant evaporation temperature TL to become the target refrigerant evaporation temperature TEO determined in step S5 is calculated by the following formula F5.
Grn × Ie = f (Ta, TEO, BLV) (F5)
In this formula F5, Gr in the formula F2 is Grn and TL in the formula F3 is TEO with respect to the formula F4.

  Next, in step S93, a control current Ic that becomes the necessary refrigerant flow rate Grn calculated in step S92 is provisionally determined. Specifically, in step S93, based on the required refrigerant flow rate Grn, the control current Ic is provisionally determined with reference to a control map determined in advance from the characteristic diagram of FIG.

  That is, in step S93, the value of the control current Ic is determined by feedforward control so that the estimated refrigerant evaporation temperature TL estimated in the next step S6 approaches the target evaporation temperature TEO. In this embodiment, after step S9, the control current Ic is determined (changed) again by feedback control in step S10. Therefore, in step S93, the control current Ic is temporarily determined. ing.

  Next, in step S10, a deviation En (Te-TEO) between the temperature Te of the heat exchange fin detected by the evaporator temperature sensor 24 and the target refrigerant evaporation temperature TEO is calculated, and based on this deviation En, Te is calculated. The control current Ic is changed by a feedback control method using proportional-integral control (PI control) so as to be close to TEO.

  That is, in step S10, if a change is detected in the air-side cooling load in step S8, the control current Ic temporarily determined by the feedforward control in step S9 is further changed by feedback control, and in step S8. When no change is detected in the air-side cooling load, the control current Ic output last time is changed by feedback control.

  Next, in step S11, 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 and S10 is obtained. In the next step S12, 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.

  In the present embodiment, as described above, the refrigerant-side cooling capacity is calculated using the enthalpy difference Ie estimated from the refrigerant flow rate Gr and the outside air temperature Tam detected by the flow rate sensor 26 in step S6 constituting the refrigerant-side capacity calculating means. Since Qer is calculated, the refrigerant-side cooling capacity Qer can be calculated more accurately and accurately.

  Moreover, in step S7 which comprises an air side capacity | capacitance calculation means, using the air flow amount determined from the outside air temperature Tam, the suction | inhalation air temperature Ta determined from the internal temperature Tr, and the control voltage BLV output to the ventilation fan 14a. Since the air side cooling capacity Qea is calculated, the air side cooling capacity Qea can also be calculated with high accuracy.

  Thereby, when the air side cooling load fluctuates, it is possible to improve the estimation accuracy of the estimated refrigerant evaporation temperature TL at the balance point of the air side cooling capacity Qea and the refrigerant side cooling capacity Qer shown in FIG.

  Further, in step S92, the necessary refrigerant flow rate Grn necessary to bring the estimated refrigerant evaporation temperature TL estimated with high accuracy close to the target refrigerant evaporation temperature TEO is calculated, and in step S93, it is estimated in the next step S6. The value of the control current Ic is determined by feedforward control so that the estimated refrigerant evaporation temperature TL approaches the target evaporation temperature TEO.

  Therefore, the control current Ic can be changed quickly and by an appropriate amount to sufficiently improve the response when the actual refrigerant evaporation temperature Te of the evaporator approaches the target refrigerant evaporation temperature TEO. In addition, the refrigerant evaporating temperature Te of the evaporator can be avoided from being lowered more than necessary, and frosting of the evaporator 14 can be prevented.

  Further, in the control step S8, whether or not the air-side cooling load has fluctuated is specifically determined that the control voltage BLV has changed, the inside / outside air switching door 16c has changed the air volume ratio, or the temperature setting switch. Since it is determined that the air-side cooling load has changed when at least one of the changes in the set temperature Tset is detected in step 33, the change in the air-side cooling load can be reliably detected.

(Second Embodiment)
In the first embodiment described above, it is possible to sufficiently improve the responsiveness when the refrigerant evaporation temperature Te of the actual evaporator is brought close to the target refrigerant evaporation temperature TEO and to prevent the evaporator 14 from frosting at the same time. Although the control process which can be performed is demonstrated, this embodiment demonstrates especially the control process for preventing the frost formation of the evaporator 14. FIG.

  Specifically, with respect to the first embodiment, the feedforward control in step S9 is as shown in FIG. That is, in step S9 of the present embodiment, the estimated evaporative refrigerant temperature TL is estimated in step S91. Next, when the estimated evaporative refrigerant temperature TL is smaller than the target refrigerant evaporating temperature TEO in step S91 ', the process proceeds to steps S92 and S93, and the same feedforward control as in the first embodiment is performed.

  On the other hand, if the estimated evaporative refrigerant temperature TL is not lower than the target refrigerant evaporating temperature TEO in step S91 ', the process proceeds to step S10. Other control flows and the configuration of the refrigeration cycle apparatus 10 are the same as those in the first embodiment. Moreover, in drawings after FIG. 8, the same code | symbol is attached | subjected to the same or equivalent part with respect to 1st Embodiment.

  As described above, the target refrigerant evaporation temperature TEO has a value equal to or higher than TEOmn in order to prevent the evaporator 14 from frosting. Therefore, when TEO> TL, there is a possibility that TEOmn> TL, and the evaporator 14 may be frosted.

  On the other hand, in this embodiment, when TEO> TL, the same feedforward control as that in the first embodiment is performed, and in particular, it is avoided that the refrigerant evaporation temperature Te of the evaporator is decreased more than necessary. Thus, frosting of the evaporator 14 can be prevented.

(Third embodiment)
In the above-described embodiment, the example in which the discharge capacity changing means for changing the refrigerant discharge capacity of the variable capacity compressor 11 is configured by the electromagnetic capacity control valve 11a has been described. In this embodiment, as shown in FIG. Next, an example in which the compressor 11 ′ is a fixed capacity compressor and the discharge capacity changing means is constituted by an electric motor 11b that drives the compressor 11 ′ will be described. In addition, as compressor 11 ', various compression mechanisms, such as a scroll type compressor and a vane type compressor, are employable.

  The compressor 11 ′ and the electric motor 11 b of the present embodiment are housed in the same housing and are integrally configured as a so-called electric compressor. Further, in the present embodiment, the flow rate sensor 26 is eliminated, and a rotation speed sensor 27 that detects the rotation speed Nc of the compressor 11 ′ (electric motor 11 b) is provided in the housing.

Furthermore, in this embodiment, Gr calculated by the following formula F6 is used as the refrigerant flow rate Gr when calculating the refrigerant side cooling capacity Qer in step S6.
Gr = ηv × Nc × Vc × ρ (F6)
Note that ηv is the volumetric efficiency of the compressor 11 ′, Vc is the discharge capacity per rotation of the compressor 11, and ρ is the refrigerant density sucked into the compressor 11 ′.

  Here, the density of the refrigerant sucked into the compressor 11 ′ is determined by the compressor 11 ′ intake refrigerant temperature and the intake refrigerant pressure. Furthermore, since the suction refrigerant temperature has a value substantially equal to the refrigerant evaporation temperature of the evaporator 14, the refrigerant density ρ can be expressed as a function of the estimated refrigerant evaporation temperature TL of the evaporator 14.

  Therefore, in the present embodiment, the rotational speed sensor 27 constitutes a flow rate detecting means. In step S6 of the present embodiment, the refrigerant side cooling capacity Qer is calculated with the estimated evaporative refrigerant temperature TL as a variable.

  Further, in step S91 of the present embodiment, the refrigerant evaporation temperature that satisfies the equation F4 is estimated as the estimated refrigerant evaporation temperature TL using the Qer calculated from the equation F6. In steps S93 and S10, a rotation speed control signal for the electric motor 11b is determined. Other configurations and control flow are the same as those in the first embodiment.

  As described above, even if the refrigerant flow rate Gr is calculated using the rotation speed Nc, the refrigerant-side cooling capacity Qer can be calculated with high accuracy, so that the estimation accuracy of the estimated refrigerant evaporation temperature TL is improved as in the first embodiment. be able to. As a result, the same effect as that of the first embodiment can be obtained.

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

  (1) In the above-described embodiment, in step S8, the control voltage BLV (the amount of air blown by the blower fan 14a) has changed, the inside / outside air switching door 16c has changed the air volume ratio, or the temperature setting switch 33. It is determined that the air-side cooling load has changed when at least one of the changes in the set temperature Tset is detected by the above. Of course, air is detected when any one of the above is detected. It may be determined that the side cooling load has fluctuated.

  Further, when the control signal output to the control voltage BLV and the inside / outside air switching door 16c is changed based on the target blowing temperature TAO as in the above-described embodiment, the air-side cooling is performed when the TAO changes. It may be determined that the load has fluctuated.

  (2) In the second embodiment described above, when TEO> TL, the process proceeds to steps S92 and S93 to execute the feedforward control. However, the execution condition of the feedforward control is not limited to this. For example, the feedforward control may be executed when the absolute value of the deviation (TEO-TL) between the target refrigerant evaporation temperature TEO and the estimated refrigerant evaporation temperature TL is equal to or greater than a predetermined value.

  (3) An internal heat exchanger that exchanges 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 the above-described embodiment. Thereby, the enthalpy difference (refrigeration capacity) between the inlet side refrigerant and the outlet side refrigerant in the evaporator 14 can be increased.

  (4) In the above-described embodiment, an example in which a differential pressure type flow sensor is employed as the flow sensor 26 has been described, but the type of the flow sensor 26 is not limited thereto. For example, a mass flow sensor such as a hot wire flow sensor may be employed.

  (5) 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.

  (6) 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.

  (7) In the above-described embodiment, when there is an air side load fluctuation, the feedback control of step S10 is performed after the feedforward control of step S9, but the process proceeds directly from step S9 to step S11. A control signal may be output from the air conditioning controller 20 to the electric actuator.

1 is an overall configuration diagram of a refrigeration cycle apparatus applied to a vehicle air conditioner according to a first embodiment. It is a characteristic view which shows the relationship between the control current and compressor discharge refrigerant | coolant flow volume of 1st Embodiment. It is a flowchart which shows control of the vehicle air conditioner of 1st Embodiment. It is a flowchart which shows the principal part of control of the vehicle air conditioner of 1st Embodiment. It is a characteristic view for determining target refrigerant evaporation temperature TEO of a 1st embodiment. It is a Mollier diagram which shows the state of the refrigerant | coolant 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 flowchart which shows the principal part of control of the vehicle air conditioner of 2nd Embodiment. It is a whole block diagram of the refrigerating-cycle apparatus applied to the vehicle air conditioner of 3rd Embodiment.

Explanation of symbols

11, 11 '... compressor, 11a ... electromagnetic capacity control valve, 11b ... electric motor,
12 ... radiator, 13 ... pressure control valve, 14 ... evaporator, inside / outside air switching door ... 16c,
20a ... discharge capacity control means, 26 ... flow rate sensor, 33 ... temperature setting switch,
S5 ... target evaporation temperature determining means, S6 ... refrigerant side capacity calculating means, S7 ... air side capacity calculating means,
S8: Load fluctuation determination means, S91: Evaporation temperature estimation means Gr ... Refrigerant flow rate, TEO ... Target refrigerant evaporation temperature, Qer ... Refrigerant side cooling capacity,
Qea: air-side cooling capacity, TL: estimated refrigerant evaporation temperature.

Claims (12)

A compressor (11, 11 ′) for compressing and discharging the refrigerant;
A radiator (12) for radiating the refrigerant discharged from the compressor (11, 11 ′);
Decompression means (13) for decompressing and expanding the refrigerant radiated by the radiator (12);
An evaporator (14) for evaporating the refrigerant decompressed and expanded by the decompression means (13) and cooling the blown air sent to the space to be cooled;
Discharge capacity changing means (11a, 11b) for changing the refrigerant discharge capacity of the compressor (11, 11 ′);
Discharge capacity control means (20a) for controlling the operation of the discharge capacity change means (11a, 11b);
A flow rate detection means (26) for detecting a physical quantity having a correlation with the refrigerant flow rate (Gr) circulating in the cycle;
Target evaporation temperature determining means (S5) for determining a target refrigerant evaporation temperature (TEO) in the evaporator (14);
Load fluctuation determination means (S8) for determining that fluctuation has occurred in the air-side cooling load;
Refrigerant side capacity calculating means (S6) for calculating the refrigerant side cooling capacity (Qer);
Air-side capacity calculating means (S7) for calculating the air-side cooling capacity (Qea);
Evaporation temperature estimation means (S91) which uses the refrigerant evaporation temperature of the evaporator (14) where the air side cooling capacity (Qea) and the refrigerant side cooling capacity (Qer) are equal to each other as the estimated refrigerant evaporation temperature (TL). ,
The refrigerant side capacity calculating means (S6) calculates the refrigerant side cooling capacity (Qer) using at least the detection value (Gr) of the flow rate detecting means (26),
The discharge capacity control means (20a) changes the discharge capacity so that the estimated refrigerant evaporation temperature (TL) approaches the target refrigerant evaporation temperature (TEO) when a change in the air-side cooling load is detected. A refrigeration cycle apparatus characterized by feedforward control of the operation of the means (11a, 11b). 2. The refrigeration cycle apparatus according to claim 1, wherein the load fluctuation determination unit (S <b> 8) determines that the air-side cooling load has fluctuated when the amount of blown air of the blown air changes. The blown air includes at least one of air in the space to be cooled and air outside the space to be cooled,
Furthermore, air volume ratio changing means (16c) for changing the air volume ratio between the air volume in the cooling target space and the air volume outside the cooling target space in the blown air is provided,
The load variation determining means (S8) determines that the air-side cooling load has changed when the air volume ratio changing means (16c) changes the air volume ratio. The refrigeration cycle apparatus described in 1. Furthermore, it comprises target temperature setting means (33) for setting the target temperature (Tset) of the space to be cooled,
The load variation determining means (S8) determines variation in the air-side cooling load when the target temperature (Tset) is changed. Refrigeration cycle equipment. The air side capacity calculating means (S7) correlates with the physical quantity (Tam, Tr) correlated with the intake air temperature (Ta) of the blown air on the evaporator (14) suction side, and the blown air quantity of the blown air. The air-side cooling capacity (Qea) is calculated using at least one of the physical quantity (BLV) having a certain amount and the physical quantity (Tef) having a correlation with the refrigerant evaporation temperature in the evaporator (14). The refrigeration cycle apparatus according to any one of claims 1 to 4. The refrigerant side capacity calculating means (S6) further includes an outlet side specific enthalpy (Ieo) of the evaporator (14) outlet side refrigerant and an inlet side specific enthalpy (Iei) of the evaporator (14) inlet side refrigerant. The refrigerant-side cooling capacity (Qer) is calculated using at least one of physical quantities (Tam, Tef) correlated with the enthalpy difference (Ie). The refrigeration cycle apparatus described. The pressure reducing means is a pressure control valve (13) whose valve opening is adjusted so that the high-pressure side refrigerant pressure approaches a target high pressure determined according to the high-pressure side refrigerant temperature downstream of the radiator (12). The refrigeration cycle apparatus according to claim 1, wherein the refrigeration cycle apparatus is provided. 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 any one of claims 1 to 7, wherein the flow rate detection means includes a flow rate sensor (26) for detecting a refrigerant flow rate (Gr) circulating in the cycle. . The compressor is a fixed capacity compressor (11 ′) having a fixed discharge capacity,
The discharge capacity changing means is an electric motor (11b) that rotationally drives the fixed displacement compressor (11 ′),
The flow rate detection means includes a rotation speed detection means (27) for detecting the rotation speed of the fixed displacement compressor (11 '). The refrigeration cycle apparatus described in 1. The refrigeration according to any one of claims 1 to 9, wherein at least a part of the flow rate detection means (26, 27) is configured integrally with the compressor (11, 11 '). Cycle equipment. The refrigeration cycle apparatus according to any one of claims 1 to 10, wherein the compressor (11, 11 ') increases the pressure of the refrigerant until the pressure becomes equal to or higher than a critical pressure. The refrigeration cycle apparatus according to any one of claims 1 to 11, wherein the refrigerant is carbon dioxide.

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