JP2018077020A - Refrigeration cycle device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a refrigerating cycle apparatus capable of configuring a gas injection cycle, which can suppress a decrease in heating capacity even when frost formation of an outdoor heat exchanger progresses without complicating the cycle. .. In a refrigeration cycle apparatus 10, in a heating mode, a compressor 11, an indoor condenser 12, a first expansion valve 14a, a gas-liquid separator 16, an outdoor heat exchanger 20, and an accumulator 24 are used. , Gas injection cycle is configured. Further, according to the refrigeration cycle apparatus 10, whether or not the outdoor heat exchanger 20 is frosted to some extent and the amount of heat absorbed by the outdoor heat exchanger 20 is reduced depends on the outside air temperature Tam and the outdoor heat exchange. It is determined using the vessel temperature Ts. When the outdoor heat exchanger 20 is frosted to some extent and the amount of heat absorbed by the outdoor heat exchanger 20 is reduced, the opening degree of the first expansion valve 14a is adjusted to adjust the opening degree of the indoor condenser 12. The dryness of the refrigerant on the outlet side is controlled. [Selection diagram] Fig. 3

Description

  The present invention relates to a refrigeration cycle apparatus capable of configuring a gas injection cycle by switching a refrigerant circuit.

  Conventionally, a so-called gas injection cycle (economizer refrigeration cycle) is known as one of refrigeration cycle devices applied to vehicle air conditioners. This gas injection cycle is switched when the cycle efficiency (COP) is improved during heating operation.

  In the gas injection cycle, the refrigerant is boosted in multiple stages by two compression mechanisms, a low-stage compression mechanism and a high-stage compression mechanism, and the intermediate-pressure gas-phase refrigerant of the cycle separated by the gas-liquid separator is reduced to the low-stage side. The refrigerant discharged from the compression mechanism is merged and sucked into the high-stage compression mechanism.

  Further, during heating operation in the vehicle air conditioner, frost formation in the outdoor heat exchanger becomes a problem because the outdoor heat exchanger absorbs heat from the outside air. This is because if the outdoor heat exchanger is frosted, the heat absorption capability of the outdoor heat exchanger is reduced, and the heating capability of the vehicle air conditioner is reduced.

  In a gas injection cycle applicable to a vehicle air conditioner, the inventions described in Patent Documents 1 and 2 are known as inventions made in this regard.

  The refrigeration cycle apparatus described in Patent Document 1 has a gas injection cycle that uses a gas-liquid separator, and uses the high-pressure side refrigerant pressure of the refrigeration cycle during heating operation to improve the heating capacity of the refrigeration cycle. It is configured to determine excess or deficiency. When it is determined that the heating capacity is insufficient, the flow rate of the intermediate-pressure gas-phase refrigerant sucked into the compressor (that is, the gas injection amount) is controlled to increase.

  On the other hand, the vehicle air conditioner described in Patent Document 2 bypasses the liquid refrigerant discharged from the radiator when the outdoor heat exchanger is frosted, and does not perform heat absorption in the outdoor heat exchanger. It is comprised so that it may flow into. Therefore, in the vehicle air conditioner of Patent Document 2, the flow of the refrigerant is bypassed along with the frost formation of the outdoor heat exchanger, thereby preventing the heat absorption in the outdoor heat exchanger and the progress of the frost formation accompanying the heat absorption.

JP 2013-212799 A Japanese Patent Application Laid-Open No. 2014-226979

  However, in the invention described in Patent Document 1, whether or not the heating capacity in the refrigeration cycle is determined based on only the high-pressure refrigerant pressure in the refrigeration cycle, and the flow rate of the intermediate-pressure gas-phase refrigerant is increased when the shortage is large. For this reason, in invention of patent document 1, the fall degree of the heating capability resulting from the frost formation of an outdoor heat exchanger was not able to be caught accurately. That is, in the invention of Patent Document 1, it is assumed that an appropriate amount of gas injection cannot be introduced into the compressor and the heating capacity cannot be improved appropriately.

  Moreover, in the invention described in Patent Document 2, in order to suppress the progress of frost formation and a decrease in heating capacity in the outdoor heat exchanger, an accumulator provided on the blowing side of the compressor, It is necessary to arrange from the refrigerant outlet side of the radiator to the inlet side of the accumulator. For this reason, in the invention of Patent Document 2, the arrangement of the bypass flow path further complicates the refrigerant path in the entire apparatus.

  In view of the above-described points, the present invention provides a refrigeration cycle apparatus capable of suppressing a decrease in heating capacity even when frosting of an outdoor heat exchanger proceeds without complicating the cycle.

In order to achieve the object, the refrigeration cycle apparatus according to claim 1,
An intermediate pressure port (which compresses the low-pressure refrigerant sucked from the suction port (11a) until it becomes high-pressure refrigerant and discharges it from the discharge port (11c). A compressor (11) having 11b);
A radiator (12) for exchanging heat between the high-pressure refrigerant discharged from the discharge port (11c) and the heat exchange target fluid;
A high-stage decompression section (14a) that depressurizes the high-pressure refrigerant flowing out of the radiator (12) and adjusts the degree of supercooling or dryness of the refrigerant on the outlet side of the radiator (12);
A gas-liquid separator (16) that separates the gas-liquid of the refrigerant that has been decompressed until it becomes an intermediate-pressure refrigerant in the high-stage decompression unit (14a);
An intermediate pressure refrigerant passage (18b) for guiding the gas-phase refrigerant separated in the gas-liquid separation section (16) to the intermediate pressure port (11b) side;
A low-stage decompression section (17) for decompressing the liquid-phase refrigerant separated in the gas-liquid separation section (16) until it becomes a low-pressure refrigerant;
An outdoor heat exchanger (20) for exchanging heat of the refrigerant decompressed in the low-stage decompression section (17) with the outside air and flowing it out to the upstream side of the suction port (11a);
A decompression control section (40b) for controlling the operation of the high stage decompression section (14a);
A frosting state determination unit (S22, S23, S24, S32) for determining whether or not the frosting state in the outdoor heat exchanger has progressed to a predetermined stage,
When it is determined that the frost formation in the outdoor heat exchanger (20) has progressed to a predetermined level, the pressure reduction control unit (40b) adjusts the opening degree of the high-stage pressure reduction unit (14a) to release heat. The refrigerant on the outlet side of the vessel (12) is controlled to dryness.

  In this refrigeration cycle apparatus, the frosting condition determination unit determines that the frosting condition in the outdoor heat exchanger is at a predetermined stage (for example, the situation where the defrosting operation is not required, but the heat exchange capacity in the outdoor heat exchanger is If it is determined that the process has progressed to a level that has been reduced to a certain extent, the refrigerant on the outlet side of the radiator is set to dryness control by the decompression control unit. As a result, the flow rate of the gas-phase refrigerant separated in the gas-liquid separation unit increases, so that the flow rate of the gas-phase refrigerant flowing into the intake port of the compressor as the intermediate-pressure refrigerant is increased via the intermediate-pressure refrigerant passage. be able to.

  Therefore, according to this refrigeration cycle apparatus, when the frosting state in the outdoor heat exchanger has progressed to a predetermined stage, the refrigerant flow rate discharged from the discharge port of the compressor is increased to ensure the heat dissipation amount in the radiator. can do. Thereby, even if it is a case where frost formation of an outdoor heat exchanger has progressed to the predetermined stage, the refrigeration cycle apparatus can suppress a decrease in heating capacity accompanying frost formation of the outdoor heat exchanger.

  Further, in this refrigeration cycle apparatus, since the decrease in the heating capacity due to the frost formation of the outdoor heat exchanger is suppressed by the control by the decompression control unit, the decrease in the heating capacity is dealt with without complicating the cycle. be able to.

  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 the embodiment described later.

It is a whole block diagram which shows the refrigerant circuit at the time of the air_conditioning | cooling mode and serial dehumidification heating mode of the vehicle air conditioner which concerns on 1st Embodiment. It is a whole block diagram which shows the refrigerant circuit at the time of the parallel dehumidification heating mode of the vehicle air conditioner which concerns on 1st Embodiment. It is a whole block diagram which shows the refrigerant circuit at the time of the heating mode of the vehicle air conditioner which concerns on 1st Embodiment. It is a block diagram which shows the control system of the vehicle air conditioner which concerns on 1st Embodiment. It is a flowchart of the main routine of the vehicle air conditioner which concerns on 1st Embodiment. 4 is a flowchart of a subroutine for selecting a control mode in a heating mode in the vehicle air volume device according to the first embodiment. It is a Mollier diagram which shows the state of the refrigerant | coolant at the time of supercooling degree control in the heating mode which concerns on 1st Embodiment. It is a Mollier diagram which shows the state of the refrigerant | coolant at the time of dryness control in the heating mode which concerns on 1st Embodiment. It is a flowchart of the subroutine which selects the control mode at the time of heating mode in the vehicle air quantity apparatus which concerns on 2nd Embodiment.

(First embodiment)
Hereinafter, based on embodiment (1st Embodiment) which applied the refrigerating-cycle apparatus based on this invention to the refrigerating-cycle apparatus 10 which comprises the vehicle air conditioner 1 used in order to adjust vehicle interior space to appropriate temperature. Detailed description will be given with reference to the drawings. In the following embodiments, the same or equivalent parts are denoted by the same reference numerals in the drawings.

  A refrigeration cycle apparatus 10 according to the first embodiment is applied to a vehicle air conditioner 1 for a hybrid vehicle that obtains driving force for vehicle travel from an internal combustion engine (that is, an engine) and a travel electric motor. The refrigeration cycle apparatus 10 fulfills a function of cooling or heating the blown air blown into the vehicle interior, which is the air-conditioning target space, in the vehicle air conditioner 1.

  The refrigeration cycle apparatus 10 includes a cooling mode refrigerant circuit (see FIG. 1), a serial dehumidification heating mode refrigerant circuit (see FIG. 1), a parallel dehumidification heating mode refrigerant circuit (see FIG. 2), and a heating mode refrigerant circuit (see FIG. 1). 3) can be switched. In FIGS. 1-3, the flow of the refrigerant | coolant in each operation mode is shown by the thick line arrow.

  In the vehicle air conditioner 1, the cooling mode is an operation mode in which the vehicle interior is cooled by cooling the blown air and blowing it out into the vehicle interior. The dehumidifying heating mode is an operation mode in which dehumidifying heating in the vehicle interior is performed by reheating the blown air that has been cooled and dehumidified and blowing it out into the vehicle interior. The heating mode is an operation mode in which the vehicle interior is heated by heating the blown air and blowing it out into the vehicle interior.

  The refrigeration cycle apparatus 10 employs an HFC refrigerant (specifically, R134a) as a refrigerant, and constitutes a vapor compression subcritical refrigeration cycle in which the pressure of the refrigerant discharged from the compressor 11 does not exceed the critical pressure of the refrigerant. doing. Refrigerating machine oil for lubricating the compressor 11 is mixed in the refrigerant, and a part of the refrigerating machine oil circulates in the cycle together with the refrigerant.

  In the refrigeration cycle apparatus 10, the compressor 11 draws in refrigerant, compresses it, and discharges it. The compressor 11 is arrange | positioned in the hood of a vehicle. The compressor 11 is configured such that two compression mechanisms, a low-stage compression mechanism and a high-stage compression mechanism, and an electric motor that rotationally drives both compression mechanisms are housed in a housing that forms an outer shell thereof. Has been. That is, the compressor 11 is a two-stage booster type electric compressor.

  The housing of the compressor 11 is provided with a suction port 11a, an intermediate pressure port 11b, and a discharge port 11c. The suction port 11a is a suction port that sucks low-pressure refrigerant from the outside of the housing into the low-stage compression mechanism. The discharge port 11c is a discharge port that discharges the high-pressure refrigerant discharged from the high-stage compression mechanism to the outside of the housing.

  The intermediate pressure port 11b is an intermediate pressure inlet for allowing the intermediate pressure refrigerant to flow from the outside to the inside of the housing and to merge with the refrigerant in the compression process from low pressure to high pressure. That is, the intermediate pressure port 11b is connected to the discharge port side of the low-stage compression mechanism and the suction port side of the high-stage compression mechanism inside the housing.

  The operation (the number of rotations) of the electric motor is controlled by a control signal output from the air conditioning controller 40 described later. The refrigerant discharge capacity of the compressor 11 is changed by this rotation speed control.

  In the first embodiment, the compressor 11 in which two compression mechanisms are accommodated in one housing is adopted, but various types can be adopted as long as it is a two-stage booster type compressor. In other words, if it is possible to flow the intermediate pressure refrigerant from the intermediate pressure port 11b and join the refrigerant in the compression process from the low pressure to the high pressure, there is one fixed capacity type compression mechanism and an electric motor that rotationally drives the compression mechanism. The electric compressor may be configured such that the motor is housed inside the housing.

  Further, one two-stage booster compressor 11 may be configured by connecting a low-stage compressor and a high-stage compressor in series. In this case, the suction port of the low-stage compressor disposed on the low-stage side is referred to as a suction port 11a, and the discharge port of the high-stage compressor disposed on the high-stage side is referred to as a discharge port 11c. And the intermediate pressure port 11b should just be provided in the refrigerant path which connects the discharge port of a low stage side compressor, and the suction port of a high stage side compressor.

  The refrigerant inlet side of the indoor condenser 12 is connected to the discharge port 11 c of the compressor 11. The indoor condenser 12 is arrange | positioned inside the air-conditioning case 31 of the indoor air-conditioning unit 30 mentioned later. The indoor condenser 12 exchanges heat between the high-pressure refrigerant discharged from the high-stage compression mechanism of the compressor 11 and the blown air that has passed through the indoor evaporator 23 described later, and heat exchange for heating that heats the blown air. It is a vessel.

  A first three-way joint 13 a is connected to the refrigerant outlet side of the indoor condenser 12. The first three-way joint 13a has three inflow / outflow ports communicating with each other, and is connected to the refrigerant outlet side of the indoor condenser 12 through one outflow / inlet side. As such a three-way joint, one formed by joining a plurality of pipes or one formed by providing a plurality of refrigerant passages in a metal block or a resin block can be adopted.

  Furthermore, the refrigeration cycle apparatus 10 includes a plurality of three-way joints such as a second three-way joint 13b to a fourth three-way joint 13d as described later. The basic configuration of the second three-way joint 13b to the fourth three-way joint 13d is the same as that of the first three-way joint 13a.

  And the inlet side of the 1st expansion valve 14a is connected to one outflow port of the 1st three-way coupling 13a. In addition, one inlet side of the second three-way joint 13b is connected to the other outlet of the first three-way joint 13a via the first refrigerant passage 18a. The first refrigerant passage 18a connects the other outlet side of the first three-way joint 13a and one inlet side of the second three-way joint 13b.

  A first on-off valve 15a is disposed in the first refrigerant passage 18a. The first on-off valve 15a is an electromagnetic valve that opens and closes the first refrigerant passage 18a. Furthermore, the refrigeration cycle apparatus 10 includes a second on-off valve 15b to a fourth on-off valve 15d, as will be described later. The basic configuration of the second on-off valve 15b to the fourth on-off valve 15d is the same as that of the first on-off valve 15a.

  The first on-off valve 15a to the fourth on-off valve 15d can switch the refrigerant circuit in each operation mode described above by opening and closing the refrigerant passage. Accordingly, the first on-off valve 15a to the fourth on-off valve 15d are refrigerant circuit switching devices that switch the refrigerant circuit of the cycle. The operations of the first on-off valve 15 a to the fourth on-off valve 15 d are controlled by a control voltage output from the air conditioning control device 40.

  The first expansion valve 14a is a high-stage decompression device that decompresses the high-pressure refrigerant flowing out of the indoor condenser 12 at least in the heating mode. The first expansion valve 14a is an electric variable throttle mechanism that includes a valve body that can change the throttle opening degree and an electric actuator that changes the opening degree of the valve body. The first expansion valve 14a functions as a high-stage pressure reducing unit in the present invention.

  Furthermore, the refrigeration cycle apparatus 10 includes a second expansion valve 14b as will be described later. The basic configuration of the second expansion valve 14b is the same as that of the first expansion valve 14a. The first expansion valve 14a and the second expansion valve 14b have a fully-open function that functions as a simple refrigerant passage without substantially exhibiting a flow rate adjusting action and a refrigerant pressure-reducing action by fully opening the valve opening degree, and a valve opening degree. Is fully closed to close the refrigerant passage.

  And the 1st expansion valve 14a and the 2nd expansion valve 14b can switch the refrigerant circuit of each operation mode mentioned above by this fully open function and a fully closed function. That is, the first expansion valve 14a and the second expansion valve 14b have a function as a refrigerant circuit switching device. The operations of the first expansion valve 14 a and the second expansion valve 14 b are controlled by a control signal (control pulse) output from the air conditioning control device 40.

  The refrigerant inlet of the gas-liquid separator 16 is connected to the outlet of the first expansion valve 14a. The gas / liquid separator 16 is a gas / liquid separator that separates the gas / liquid of the refrigerant flowing out from the first expansion valve 14a, and functions as the gas / liquid separator in the present invention. Specifically, as the gas-liquid separator 16, a centrifugal separation method (cyclonic separator method) that separates the gas-liquid refrigerant by the action of centrifugal force generated by swirling the refrigerant flowing into the internal space of the cylindrical main body. Is adopted.

  Furthermore, the internal volume of the gas-liquid separator 16 according to the first embodiment is such that excess refrigerant cannot be substantially accumulated even when a load fluctuation occurs in the cycle and the refrigerant circulation flow rate circulating in the cycle fluctuates. It is in volume.

  An intermediate pressure port 11b of the compressor 11 is connected to the gas phase refrigerant outlet of the gas-liquid separator 16 via a second refrigerant passage 18b. The second refrigerant passage 18 b connects the gas-phase refrigerant outlet of the gas-liquid separator 16 and the intermediate pressure port 11 b of the compressor 11. A second opening / closing valve 15b is disposed in the second refrigerant passage 18b, and the second refrigerant passage 18b is opened and closed by its operation.

  An inlet side of the fixed throttle 17 is connected to the liquid-phase refrigerant outlet of the gas-liquid separator 16. The fixed throttle 17 is a low-stage decompression device that decompresses the liquid-phase refrigerant flowing out of the gas-liquid separator 16 until it becomes a low-pressure refrigerant, and functions as a low-stage decompression unit in the present invention. As the fixed throttle 17, a nozzle, an orifice, a capillary tube or the like having a fixed throttle opening can be employed. The refrigerant inlet side of the outdoor heat exchanger 20 is connected to the outlet side of the fixed throttle 17.

  Further, a third refrigerant passage 18 c is connected to the liquid-phase refrigerant outlet of the gas-liquid separator 16. The third refrigerant passage 18 c is configured as a bypass passage for the fixed throttle 17. That is, the third refrigerant passage 18 c guides the liquid-phase refrigerant separated by the gas-liquid separator 16 to the refrigerant inlet side of the outdoor heat exchanger 20 by bypassing the fixed throttle 17. A third on-off valve 15c is disposed in the third refrigerant passage 18c, and opens and closes the third refrigerant passage 18c by its operation.

  Here, the pressure loss that occurs when the refrigerant passes through the third on-off valve 15 c is extremely smaller than the pressure loss that occurs when the refrigerant passes through the fixed throttle 17. Therefore, when the third on-off valve 15c is opened, most of the liquid-phase refrigerant that has flowed out of the gas-liquid separator 16 does not pass through the fixed throttle 17 and passes through the third refrigerant passage 18c. 20 flows into.

  The outdoor heat exchanger 20 is a heat exchanger that exchanges heat between the refrigerant flowing out of the first expansion valve 14a and the outside air blown from the blower fan 20a. The outdoor heat exchanger 20 is disposed on the front side in the vehicle bonnet.

  The outdoor heat exchanger 20 functions as a radiator that radiates high-pressure refrigerant at least in the cooling mode, and functions as an evaporator that evaporates low-pressure refrigerant decompressed by the first expansion valve 14a at least in the heating mode. The blower fan 20a is an electric blower in which the rotation speed (that is, the blowing capacity) is controlled by a control voltage output from the air conditioning control device 40, and is configured by a brushless electric fan.

  The refrigerant outlet of the outdoor heat exchanger 20 is connected to the inlet side of the third three-way joint 13c. The other inflow port side of the second three-way joint 13b is connected to one outflow port of the third three-way joint 13c.

  One inflow side of the fourth three-way joint 13d is connected to the other outflow port of the third three-way joint 13c via a fourth refrigerant passage 18d. The fourth refrigerant passage 18d connects the other outlet side of the third three-way joint 13c and one inlet side of the fourth three-way joint 13d. A fourth open / close valve 15d is disposed in the fourth refrigerant passage 18d, and opens and closes the fourth refrigerant passage 18d by its operation.

  A check valve 21 is arranged in the refrigerant passage that connects one outlet side of the third three-way joint 13c and the other inlet side of the second three-way joint 13b. The check valve 21 allows the refrigerant to flow from the third three-way joint 13c side (that is, the outdoor heat exchanger 20 side) to the second three-way joint 13b side (that is, the second expansion valve 14b side). It functions to inhibit the refrigerant from flowing from the three-way joint 13b side to the third three-way joint 13c side.

  The inlet side of the second expansion valve 14b is connected to the outlet of the second three-way joint 13b. The second expansion valve 14b is an electric variable throttle mechanism that depressurizes the refrigerant that has flowed out of the outdoor heat exchanger 20 at least in the cooling mode. The refrigerant inlet side of the indoor evaporator 23 is connected to the outlet side of the second expansion valve 14b.

  The indoor evaporator 23 is disposed in the air conditioning case 31 of the indoor air conditioning unit 30. The indoor evaporator 23 evaporates the low-pressure refrigerant by exchanging heat between the low-pressure refrigerant decompressed by the second expansion valve 14b and the blown air blown from the blower 32 in the cooling mode and the dehumidifying heating mode. Thereby, the indoor evaporator 23 functions as a cooling heat exchanger that cools the blown air by causing the low-pressure refrigerant to exhibit an endothermic effect.

  An inlet side of the evaporation pressure adjusting valve 26 is connected to the refrigerant outlet side of the indoor evaporator 23. The evaporation pressure adjusting valve 26 is configured by a mechanical mechanism, and adjusts the refrigerant evaporation pressure in the indoor evaporator 23 to a reference pressure or higher that can suppress frost formation in order to suppress frost formation in the indoor evaporator 23. Fulfills the function. In other words, the evaporation pressure adjustment valve 26 functions to adjust the refrigerant evaporation temperature in the indoor evaporator 23 to a reference temperature or higher that can suppress frost formation.

  The other inflow side of the fourth three-way joint 13d is connected to the outlet of the evaporation pressure adjusting valve 26. The inlet side of the accumulator 24 is connected to the outlet of the fourth three-way joint 13d. The accumulator 24 is a gas-liquid separator that separates the gas-liquid of the refrigerant that has flowed into the accumulator 24 and stores excess liquid-phase refrigerant in the cycle. The suction port 11 a side of the compressor 11 is connected to the gas phase refrigerant outlet of the accumulator 24.

  Next, the indoor air conditioning unit 30 will be described. The indoor air conditioning unit 30 constitutes a part of the vehicle air conditioner 1 and blows out the blown air whose temperature has been adjusted by the refrigeration cycle apparatus 10 into the vehicle interior. The indoor air conditioning unit 30 is disposed inside the instrument panel (instrument panel) at the forefront of the vehicle interior. The indoor air conditioning unit 30 accommodates a blower 32, an indoor evaporator 23, a heater core 39, an indoor condenser 12, and the like in an air passage formed in an air conditioning case 31 that forms an outer shell thereof.

  The heater core 39 is an auxiliary heating heat exchanger that auxiliary heats the blown air by exchanging heat between the engine coolant and the blown air that has passed through the indoor evaporator 23. The heater core 39 is connected to an engine coolant circuit that circulates engine coolant.

  The air conditioning case 31 forms an air passage for the blown air blown into the vehicle interior, and is formed of a resin (for example, polypropylene) having a certain degree of elasticity and excellent in strength.

  An inside / outside air switching device 33 is disposed on the most upstream side of the air flow of the air conditioning case 31. The inside / outside air switching device 33 switches and introduces inside air (vehicle compartment air) and outside air (vehicle compartment outside air) into the air conditioning case 31.

  Specifically, the inside / outside air switching device 33 continuously adjusts the opening area of the inside air introduction port for introducing the inside air into the air conditioning case 31 and the outside air introduction port for introducing the outside air by the inside / outside air switching door. The rate of introduction between the amount of air introduced and the amount of outside air introduced is changed. The inside / outside air switching door is driven by an electric actuator for the inside / outside air switching door, and the operation of the electric actuator is controlled by a control signal output from the air conditioning control device 40.

  A blower 32 is arranged on the downstream side of the blown air flow of the inside / outside air switching device 33. The blower 32 is an electric blower that drives a centrifugal multiblade fan with an electric motor, and blows air sucked through the inside / outside air switching device 33 toward the vehicle interior. The number of rotations (that is, the blowing capacity) of the blower 32 is controlled by the control voltage output from the air conditioning control device 40.

  On the downstream side of the blower air flow of the blower 32, the indoor evaporator 23, the heater core 39, and the indoor condenser 12 are arranged in this order with respect to the blown air flow. In other words, the indoor evaporator 23 is arranged on the upstream side of the air flow with respect to the heater core 39 and the indoor condenser 12.

  A bypass passage 35 is provided in the air conditioning case 31. The bypass passage 35 is configured to flow the blown air after passing through the indoor evaporator 23, bypassing the heater core 39 and the indoor condenser 12.

  An air mix door 34 is disposed in the air conditioning case 31 on the downstream side of the blower air flow of the indoor evaporator 23 and on the upstream side of the blower air flow of the heater core 39 and the indoor condenser 12. The air mix door 34 adjusts the air volume ratio between the air volume of the blown air passing through the indoor condenser 12 and the air volume of the blown air passing through the bypass passage 35 among the blown air after passing through the indoor evaporator 23. It is an adjustment unit.

  The air mix door 34 is driven by an electric actuator for the air mix door. The operation of the electric actuator is controlled by a control signal output from the air conditioning controller 40.

  A merging space 36 is formed on the downstream side of the blower air flow of the indoor condenser 12 and the bypass passage 35. The merge space 36 is formed so that the blown air heated by exchanging heat with the refrigerant in the heater core 39 and the indoor condenser 12 and the blown air that has not passed through the bypass passage 35 are merged. . For this reason, the air mix door 34 adjusts the air volume ratio, thereby adjusting the temperature of the blown air that merges in the merge space 36.

  At the most downstream portion of the air flow of the air conditioning case 31, an opening hole for blowing out the blown air whose temperature is adjusted in the merge space 36 is arranged. Specifically, as the opening holes, a defroster opening hole 37a, a face opening hole 37b, and a foot opening hole 37c are provided.

  The defroster opening hole 37a is an opening hole for blowing out the conditioned air toward the inner surface of the vehicle front window glass. The face opening hole 37b is an opening hole for blowing out the conditioned air toward the upper body of the passenger in the passenger compartment. The foot opening hole 37c is an opening hole for blowing out the conditioned air toward the feet of the occupant.

  Further, a defroster door 38a, a face door 38b, and a foot door 38c are arranged on the upstream side of the blowing air flow of the defroster opening hole 37a, the face opening hole 37b, and the foot opening hole 37c, respectively. The defroster door 38a functions to adjust the opening area of the defroster opening hole 37a. The face door 38b functions to adjust the opening area of the face opening hole 37b. The foot door 38c functions to adjust the opening area of the foot opening hole 37c.

  The defroster door 38a, the face door 38b, and the foot door 38c constitute a blowing mode switching device that opens and closes the defroster opening hole 37a to the foot opening hole 37c and switches the blowing mode. The defroster door 38a to the foot door 38c are rotated by a door electric actuator via a link mechanism or the like. The operation of the electric actuator is controlled by a control signal output from the air conditioning controller 40.

  The blower air flow downstream side of the defroster opening hole 37a, the face opening hole 37b, and the foot opening hole 37c is a face air outlet, a foot air outlet, and a defroster air outlet provided in the vehicle interior via ducts that form air passages, respectively. It is connected to the.

  Specific examples of the blowing mode switched by the blowing mode switching device include a face mode, a bi-level mode, and a foot mode.

  The face mode is a blowout mode in which the face opening hole 37b is fully opened and blown air is blown out from the face blowout opening toward the upper body of the passenger in the passenger compartment. The bi-level mode is a blow-out mode in which both the face opening hole 37b and the foot opening hole 37c are opened and blown air is blown toward the upper body and feet of the passengers in the passenger compartment. The foot mode is a blowing mode in which the foot opening hole 37c is fully opened and the defroster opening hole 37a is opened by a small opening, and blown air is mainly blown out from the foot outlet.

  Further, when the occupant manually operates a blow mode switching switch provided on the operation panel 50, the defroster mode in which the defroster opening hole 37a is fully opened and the blown air is blown from the defroster outlet to the inner surface of the vehicle front window glass may be set. it can.

  Then, the control system of the vehicle air conditioner 1 which concerns on 1st Embodiment is demonstrated, referring FIG. The air conditioning control device 40 includes a known microcomputer including a CPU, a ROM, a RAM, and the like and peripheral circuits thereof. And the air-conditioning control apparatus 40 performs various calculation and processing based on the air-conditioning control program memorize | stored in the ROM, and controls the action | operation of the various air-conditioning control apparatuses connected to the output side.

  On the output side of the air conditioning controller 40, the compressor 11, the first expansion valve 14a, the second expansion valve 14b, the first on-off valve 15a to the fourth on-off valve 15d, the blower fan 20a, the blower 32, other electric actuators, and the like. Is connected.

  An air conditioning control sensor group is connected to the input side of the air conditioning control device 40. The air conditioning control sensor group includes an inside air temperature sensor 41, an outside air temperature sensor 42, a solar radiation sensor 43, an inflow air temperature sensor 44, a first refrigerant temperature sensor 45a to a third refrigerant temperature sensor 45c, a refrigerant pressure sensor 46, and an evaporator temperature sensor. 47, an air-conditioning air temperature sensor 48, and the like. Therefore, the air conditioning control device 40 receives detection signals from these air conditioning control sensors.

  The inside air temperature sensor 41 is an inside air temperature detecting unit that detects a vehicle interior temperature (inside air temperature) Tr. The outside air temperature sensor 42 is an outside air temperature detecting unit that detects a vehicle compartment outside temperature (outside air temperature) Tam. The solar radiation sensor 43 is a solar radiation amount detection unit that detects the solar radiation amount As irradiated into the vehicle interior. The inflow air temperature sensor 44 is an inflow air temperature detector that detects the temperature of the blown air flowing into the indoor condenser 12.

  The first refrigerant temperature sensor 45 a is a first refrigerant temperature detector that detects an inlet-side refrigerant temperature Td of refrigerant that is discharged from the compressor 11 and flows into the indoor condenser 12. The second refrigerant temperature sensor 45 b is a second refrigerant temperature detector that detects the outlet-side refrigerant temperature Th of the refrigerant that has flowed out of the indoor condenser 12. The third refrigerant temperature sensor 45c is a third refrigerant temperature detection unit that detects the temperature of the refrigerant that flows out of the outdoor heat exchanger 20 (outdoor heat exchanger temperature Ts).

  The refrigerant pressure sensor 46 is a refrigerant pressure detector that detects the high-pressure side refrigerant pressure Ph in the refrigerant passage from the discharge port side of the compressor 11 to the inlet side of the first expansion valve 14a. The evaporator temperature sensor 47 is an evaporator temperature detector that detects a refrigerant evaporation temperature (evaporator temperature) Tefin in the indoor evaporator 23. The air-conditioning air temperature sensor 48 is an air-conditioning air temperature detector that detects the temperature of the blown air TAV blown from the merge space 36 into the vehicle interior.

  Further, an operation panel 50 is connected to the input side of the air conditioning control device 40 as shown in FIG. The operation panel 50 is disposed in the vicinity of the instrument panel in the front part of the vehicle interior and has various operation switches. Therefore, the air conditioning control device 40 receives operation signals from various operation switches provided on the operation panel 50. The various operation switches of the operation panel 50 include an auto switch, an operation mode switching switch, an air volume setting switch, a temperature setting switch, a blowing mode switching switch, and the like.

  The auto switch is an automatic control setting unit that manually sets or cancels the automatic control of the vehicle air conditioner 1. The operation mode changeover switch is an operation mode setting unit that manually sets the cooling mode and the like. The air volume setting switch is an air volume setting unit that manually sets the air volume of the blower 32. The temperature setting switch is a temperature setting unit that manually sets the target temperature Tset in the vehicle compartment. The blowing mode changeover switch is a blowing mode setting unit that manually sets the blowing mode.

  In the first embodiment, the air-conditioning control device 40 is configured integrally with a control unit that controls various devices to be controlled connected to the output side thereof, but is configured to control the operation of each device to be controlled. (Hardware and Software) constitutes a control unit that controls the operation of each control target device.

  For example, the configuration (hardware and software) that controls the refrigerant discharge capacity of the compressor 11 in the air conditioning control device 40 is the discharge capacity control unit 40a. The configuration for controlling the throttle opening degree of the first expansion valve 14a and the second expansion valve 14b is a decompression device control unit 40b. The configuration for controlling the operation of the refrigerant circuit switching device such as the first on-off valve 15a to the fourth on-off valve 15d is the refrigerant circuit control unit 40c. The structure which controls the ventilation capability of the ventilation fan 20a is the ventilation fan control part 40d. The structure which controls the ventilation capability of the air blower 32 is the air blower control part 40e.

  Next, the operation of the vehicle air conditioner 1 according to the first embodiment will be described. As described above, the vehicle air conditioner 1 according to the first embodiment can perform cooling, dehumidifying heating, and heating in the passenger compartment. Accordingly, in the refrigeration cycle apparatus 10, it is possible to switch between a cooling mode operation, a series dehumidifying and heating mode operation, a parallel dehumidifying and heating mode operation, and a heating mode operation.

  Switching between these operation modes is performed by executing an air conditioning control program. This air conditioning control program is executed when the auto switch of the operation panel 50 is turned on (ON) and automatic control is set. The main routine of the air conditioning control program will be described using the flowchart shown in FIG.

  First, in step S1, initialization is executed. In this initialization, initialization of flags and timers configured by the storage circuit of the air-conditioning control device 40, initial alignment of the stepping motor configuring the above-described electric actuator, and the like are performed. Next, in step S2, the detection signal of the air conditioning control sensor group and the operation signal of the operation panel 50 are read.

In step S3, based on the values of the detection signal and the operation signal read in step S2, a target blowing temperature TAO that is a target temperature of the blowing air blown into the vehicle interior is calculated based on the following formula F1.
TAO = Kset × Tset−Kr × Tr−Kam × Tam−Ks × As + C (F1)
Here, Tset is the passenger compartment set temperature set by the temperature setting switch, Tr is the inside air temperature detected by the inside air temperature sensor 41, Tam is the outside air temperature detected by the outside air temperature sensor 42, and As is detected by the solar radiation sensor 43. Is the amount of solar radiation. Kset, Kr, Kam, Ks are control gains, and C is a correction constant.

  In step S4, an operation mode is determined. Specifically, in a state where the cooling mode is set by the operation mode changeover switch of the operation panel 50, when the target blowout temperature TAO is lower than a predetermined cooling reference temperature α, the cooling mode is determined. The

  Further, in the state where the cooling mode is set by the operation mode changeover switch, the target outlet temperature TAO is equal to or higher than the cooling reference temperature α, and the outside air temperature Tam is higher than the predetermined dehumidifying heating reference temperature β. If it is, it is determined to the serial dehumidifying heating mode.

  When the target blowing temperature TAO is equal to or higher than the cooling reference temperature α and the outside air temperature Tam is equal to or lower than the dehumidifying heating reference temperature β when the cooling mode is set by the operation mode changeover switch. The operation in the parallel dehumidifying and heating mode is determined.

  When the cooling mode is not set by the operation mode switch, the heating mode is determined.

  Thus, the cooling mode is executed when the outside air temperature is relatively high, mainly in summer. The series dehumidifying heating mode is executed mainly in the spring or autumn. The parallel dehumidifying and heating mode is executed when the blown air needs to be heated with a higher heating capacity than the serial dehumidifying and heating mode, mainly in early spring or late autumn. The heating mode is executed mainly at the low outdoor temperature in winter.

  In step S5, the blowing capacity of the blower 32 is determined according to each operation mode. Specifically, the control voltage applied to the electric motor of the blower 32 is determined. The control voltage output to the blower 32 is determined with reference to a control map stored in advance in the air conditioning control device 40 based on the target blowing temperature TAO.

  This control map increases the air volume in the extremely low temperature range (maximum cooling range) and the extremely high temperature range (maximum heating range) of the target blowing temperature TAO in each operation mode, and the target blowing temperature TAO approaches the intermediate temperature range. Along with this, it is configured to reduce the air volume.

  In step S6, the blowing capacity of the blower fan 20a is determined according to each operation mode. Specifically, the control voltage applied to the electric motor of the blower fan 20a is determined. The control voltage output to the blower fan 20a is determined with reference to a control map stored in advance in the air conditioning control device 40 based on the outside air temperature Tam.

  In step S7, the suction mode is determined. That is, the control signal output to the electric actuator for the inside / outside air switching door is determined. The suction mode is determined with reference to a control map stored in advance in the air conditioning control device 40 based on the target outlet temperature TAO.

  In this control map, priority is given to the outside air mode that basically introduces outside air regardless of the operation mode, but when the target blowing temperature TAO is in the extremely low temperature region or the extremely high temperature region, the inside air is introduced. A shy mode is selected.

  In step S8, the blowing mode is determined. That is, the control signal output to the electric actuator 61 for driving each blowing mode door is determined. The blowing mode is determined with reference to a control map stored in advance in the air conditioning control device 40 based on the target blowing temperature TAO.

  This control map is configured to sequentially switch the blowing mode from the face mode to the bi-level mode to the foot mode as the target blowing temperature TAO rises from the low temperature range to the high temperature range regardless of the operation mode. Yes. Accordingly, it is easy to select the face mode mainly in summer, the bi-level mode mainly in spring and autumn, and the foot mode mainly in winter.

  In step S9, the operating states of the first expansion valve 14a and the second expansion valve 14b are determined according to each operation mode. Specifically, control signals (control pulses) output to the first expansion valve 14a and the second expansion valve 14b are determined.

  In step S10, the open / close states of the first open / close valve 15a to the fourth open / close valve 15d are determined according to each operation mode. That is, the control voltage output to the first on-off valve 15a to the fourth on-off valve 15d is determined.

  In step S11, the opening degree of the air mix door 34 is determined according to each operation mode. Specifically, the control signal output to the electric actuator for the air mix door is determined.

  In step S12, the refrigerant discharge capacity of the compressor 11 is determined according to each operation mode. That is, the control signal output to the electric motor of the compressor 11 is determined.

  And in step S13, a control signal and a control voltage are output from the air-conditioning control apparatus 40 with respect to various air-conditioning control apparatuses so that the control state determined by the above-mentioned step S6-step S12 may be obtained. In continuing step S14, it waits for control period (tau), and if progress of control period (tau) is determined, it will return to step S2. Below, the operation | movement of each operation mode is demonstrated.

(A) Cooling mode In the cooling mode, the first expansion valve 14a is fully opened, and the second expansion valve 14b is in a throttle state that exerts a pressure reducing action. Further, the air conditioning control device 40 closes the first on-off valve 15a, the second on-off valve 15b, and the fourth on-off valve 15d, and opens the third on-off valve 15c.

  Thereby, in the cooling mode, as shown in FIG. 1, the refrigerant in the order of the compressor 11 → the outdoor heat exchanger 20 → the second expansion valve 14 b → the indoor evaporator 23 → the evaporation pressure adjusting valve 26 → the accumulator 24 → the compressor 11. Constitutes a vapor compression refrigeration cycle.

  With this cycle configuration, the air conditioning control device 40 controls the operation of the compressor 11 so that the blown air blown out from the indoor evaporator 23 becomes the target evaporator temperature TEO. The target evaporator temperature TEO is determined so as to decrease as the target outlet temperature TAO decreases. The target evaporator temperature TEO is determined within a range in which frost formation of the indoor evaporator 23 can be suppressed.

  Further, the air conditioning control device 40 controls the operation of the second expansion valve 14b based on the pressure of the refrigerant flowing into the second expansion valve 14b so that the COP of the cycle approaches the maximum value. Further, the air conditioning control device 40 displaces the air mix door 34 so as to fully open the bypass passage 35 and fully closes the ventilation path on the indoor condenser 12 and heater core 39 side.

  In the refrigeration cycle apparatus 10 in the cooling mode, the outdoor heat exchanger 20 functions as a radiator, and the indoor evaporator 23 functions as an evaporator. Then, the heat absorbed from the blown air when the refrigerant evaporates in the indoor evaporator 23 is radiated to the outside air in the outdoor heat exchanger 20. Thereby, blowing air can be cooled.

  Therefore, in the cooling mode, the vehicle interior can be cooled by blowing the blown air cooled by the indoor evaporator 23 into the vehicle interior.

(B) Serial dehumidification heating mode In serial dehumidification heating mode, the air-conditioning control apparatus 40 makes the 1st expansion valve 14a and the 2nd expansion valve 14b the throttle state which each exhibits a pressure reduction effect | action. Further, the air conditioning control device 40 closes the first on-off valve 15a, the second on-off valve 15b, and the fourth on-off valve 15d, and opens the third on-off valve 15c.

  Thereby, in the serial dehumidification heating mode, as shown in FIG. 1, the compressor 11 → the indoor condenser 12 → the first expansion valve 14a → the outdoor heat exchanger 20 → the second expansion valve 14b → the indoor evaporator 23 → the evaporation pressure. A vapor compression refrigeration cycle in which the refrigerant circulates in the order of the regulating valve 26 → accumulator 24 → compressor 11 is configured. That is, a refrigeration cycle in which the outdoor heat exchanger 20 and the indoor evaporator 23 are connected in series to the refrigerant flow is configured.

  With this cycle configuration, the air conditioning control device 40 controls the operation of the compressor 11 as in the cooling mode. The air conditioning control device 40 controls the operation of the first expansion valve 14a and the second expansion valve 14b so that the COP of the cycle approaches the maximum value based on the pressure of the refrigerant flowing into the first expansion valve 14a. . At this time, the air conditioning control device 40 decreases the throttle opening of the first expansion valve 14a and increases the throttle opening of the second expansion valve 14b as the target blowing temperature TAO increases. In addition, the air conditioning control device 40 displaces the air mix door 34 so that the bypass passage 35 is fully closed, and fully opens the ventilation path on the indoor condenser 12 and heater core 39 side.

  In the series dehumidifying heating mode, the indoor condenser 12 is caused to function as a radiator, and the indoor evaporator 23 is caused to function as an evaporator. Furthermore, when the saturation temperature of the refrigerant in the outdoor heat exchanger 20 is higher than the outside air, the outdoor heat exchanger 20 is caused to function as a radiator, and the saturation temperature of the refrigerant in the outdoor heat exchanger 20 is lower than the outside air. Makes the outdoor heat exchanger 20 function as an evaporator.

  For this reason, when the saturation temperature of the refrigerant in the outdoor heat exchanger 20 is higher than the outside air, the saturation temperature of the refrigerant in the outdoor heat exchanger 20 is lowered as the target blowing temperature TAO increases, and the outdoor heat exchanger 20 The amount of heat released from the refrigerant at 20 can be reduced. Thereby, the thermal radiation amount of the refrigerant | coolant in the indoor condenser 12 can be increased, and a heating capability can be improved.

  Further, when the saturation temperature of the refrigerant in the outdoor heat exchanger 20 is lower than the outside air, the saturation temperature of the refrigerant in the outdoor heat exchanger 20 is decreased as the target blowing temperature TAO increases, and the outdoor heat exchanger 20 The amount of heat absorbed by the refrigerant can be increased. Thereby, the thermal radiation amount of the refrigerant | coolant in the indoor condenser 12 can be increased, and a heating capability can be improved.

  Therefore, in the series dehumidifying heating mode, the air that has been dehumidified by being cooled by the indoor evaporator 23 is reheated by the indoor condenser 12 and blown into the vehicle interior, thereby performing dehumidifying heating in the vehicle interior. it can. Furthermore, the heating capability of the blowing air in the indoor condenser 12 can be adjusted by adjusting the throttle opening degree of the first expansion valve 14a and the second expansion valve 14b.

(C) Parallel dehumidification heating mode In parallel dehumidification heating mode, the air-conditioning control apparatus 40 makes the 1st expansion valve 14a and the 2nd expansion valve 14b into the throttle state which each exhibits a pressure reduction effect | action. In addition, the air conditioning control device 40 fully opens the first on-off valve 15a, the third on-off valve 15c, and the fourth on-off valve 15d, and fully closes the second on-off valve 15b.

  Thus, in the parallel dehumidifying heating mode, as shown in FIG. 2, the refrigerant circulates in the order of the compressor 11 → the indoor condenser 12 → the first expansion valve 14 a → the outdoor heat exchanger 20 → the accumulator 24 → the compressor 11. Then, a vapor compression refrigeration cycle in which the refrigerant circulates in the order of the compressor 11 → the indoor condenser 12 → the second expansion valve 14 b → the indoor evaporator 23 → the evaporation pressure regulating valve 26 → the accumulator 24 → the compressor 11. That is, a refrigeration cycle is configured in which the outdoor heat exchanger 20 and the indoor evaporator 23 are connected in parallel to the refrigerant flow.

  With this cycle configuration, the air conditioning control device 40 controls the operation of the compressor 11 as in the cooling mode. Further, the air conditioning control device 40 controls the operation of the first expansion valve 14a and the second expansion valve 14b so that the COP of the cycle approaches the maximum value based on the pressure of the refrigerant flowing into the first expansion valve 14a. . At this time, the air conditioning control device 40 decreases the throttle opening of the first expansion valve 14a and increases the throttle opening of the second expansion valve 14b as the target blowing temperature TAO increases. Further, the air conditioning control device 40 displaces the air mix door 34 so that the bypass passage 35 is fully closed, and fully opens the ventilation path on the indoor condenser 12 and heater core 39 side.

  In the parallel dehumidifying and heating mode, the indoor condenser 12 is caused to function as a radiator, and the outdoor heat exchanger 20 and the indoor evaporator 23 are caused to function as an evaporator. For this reason, the refrigerant | coolant saturation temperature of the outdoor heat exchanger 20 can be reduced with the raise of the target blowing temperature TAO, and the heat absorption amount of the refrigerant | coolant in the outdoor heat exchanger 20 can be increased. Thereby, the thermal radiation amount of the refrigerant | coolant in the indoor condenser 12 can be increased, and a heating capability can be improved.

  Therefore, in the parallel dehumidifying and heating mode, the dehumidifying and heating in the vehicle interior can be performed by reheating the blown air that has been cooled and dehumidified by the indoor evaporator 23 and blown out into the vehicle interior by the indoor condenser 12. it can. Furthermore, since the saturation temperature (evaporation temperature) of the refrigerant in the outdoor heat exchanger 20 can be made lower than the saturation temperature (evaporation temperature) of the refrigerant in the indoor evaporator 23, the heating of the blown air is higher than in the series dehumidifying heating mode. The ability can be increased.

(D) Heating mode In the heating mode, the air-conditioning control device 40 brings the first expansion valve 14a into a throttled state that exerts a pressure-reducing action, and puts the second expansion valve 14b into a closed state. Then, the air conditioning control device 40 closes the first on-off valve 15a and the third on-off valve 15c, and fully opens the second on-off valve 15b and the fourth on-off valve 15d.

  Thus, in the heating mode, as shown in FIG. 3, the discharge port 11c of the compressor 11 → the indoor condenser 12 → the first expansion valve 14a → the gas-phase refrigerant outlet of the gas-liquid separator 16 → the intermediate pressure of the compressor 11 The refrigerant circulates in the order of the port 11b, and the refrigerant circulates in the order of the liquid-phase refrigerant outlet of the gas-liquid separator 16, the fixed throttle 17, the outdoor heat exchanger 20, the accumulator 24, and the suction port 11a of the compressor 11. A gas injection cycle is configured.

  With this cycle configuration, the air conditioning control device 40 controls the operation of the compressor 11 so that the refrigerant flowing into the indoor condenser 12 reaches the target condenser temperature TCO. The target condenser temperature TCO is determined so as to increase as the target blowing temperature TAO increases. Further, the air conditioning control device 40 displaces the air mix door 34 so that the bypass passage 35 is fully closed, and fully opens the ventilation path on the indoor condenser 12 and heater core 39 side.

  And the air-conditioning control apparatus 40 controls the action | operation of the 1st expansion valve 14a so that COP of a cycle may approach the maximum value normally based on the temperature of the refrigerant | coolant which flows in into the 1st expansion valve 14a. In 1st Embodiment, the air-conditioning control apparatus 40 controls supercooling degree control and dryness control according to the frosting condition of the outdoor heat exchanger 20 by controlling the aperture opening degree of the 1st expansion valve 14a. And are used properly. This will be described in detail later with reference to the drawings.

  In the refrigeration cycle apparatus 10 in the heating mode, the indoor condenser 12 functions as a radiator, and the outdoor heat exchanger 20 functions as an evaporator. Then, the heat absorbed from the outside air when the refrigerant evaporates in the outdoor heat exchanger 20 is radiated to the blown air by the indoor condenser 12. Thereby, blowing air can be heated.

  Therefore, in the heating mode, the vehicle interior can be heated by blowing the blown air heated by the indoor condenser 12 into the vehicle interior.

  In the vehicle air conditioner 1 according to the first embodiment, the air conditioning controller 40 determines the frost formation state of the outdoor heat exchanger 20 in the heating mode, and according to the determination result, the supercooling degree control, Use dryness control properly. Specifically, the air conditioning control device 40 realizes this function by executing a subroutine shown in FIG. This subroutine is desirably executed at least after the determination of the operation mode in step S4 described above is completed and before the processing related to the determination of the operation state of each expansion valve in step S9 is started.

  First, in step S21, it is determined whether or not the current operation mode is the heating mode. That is, in step S21, it is determined whether or not the outdoor heat exchanger 20 is in an operation mode that may cause frost formation. When it determines with it being heating mode, it progresses to step S22. On the other hand, if it is determined that the mode is not the heating mode (for example, the cooling mode or the dehumidifying heating mode), this subroutine is terminated as it is.

  In step S22, the outside air temperature determination is executed based on the outside air temperature Tam detected by the outside air temperature sensor 42 and the control map shown in step S22 of FIG. This outside air temperature determination is a process for determining whether or not there is a risk of frost formation in the outdoor heat exchanger 20. In the control map shown in step S22, a hysteresis width for preventing control hunting (that is, the width of the reference outside air temperature A to the reference outside air temperature AH) is set.

  Specifically, in the outside air temperature determination, it is determined whether or not the outside air temperature Tam is lower than a predetermined reference value. More specifically, in the process in which the outside temperature Tam decreases, it is determined that there is a risk of frost formation in the outdoor heat exchanger 20 when the outside outside temperature A is not more than the reference outside temperature A defined in the control map. The determination result “1” is output. Otherwise, the determination result “0” is output.

  On the other hand, in the process in which the outdoor temperature Tam rises, when the reference outside temperature AH is higher than the reference outside temperature A, it is determined that there is no risk of frost formation in the outdoor heat exchanger 20, and the determination result “0” is output. Otherwise, the determination result “1” is output. If the determination result is “1”, the process proceeds to step S23. On the other hand, if the determination result is “0”, the process proceeds to step S26.

  In step S23, outdoor heat exchanger temperature determination is performed based on the outdoor heat exchanger temperature Ts detected by the third refrigerant temperature sensor 45c and the control map shown in step S23 of FIG. This outdoor heat exchanger temperature determination is also a process for determining whether or not there is a risk of frost formation in the outdoor heat exchanger 20. In the control map shown in step S23, a hysteresis width for preventing control hunting (that is, a width from the reference temperature B to the reference temperature BH) is set.

  Specifically, in the outdoor heat exchanger temperature determination, it is determined whether or not the outdoor heat exchanger temperature Ts is lower than a predetermined reference value. More specifically, in the process in which the outdoor heat exchanger temperature Ts is lowered, there is a risk of frost formation in the outdoor heat exchanger 20 when the temperature becomes equal to or lower than the reference temperature B specified in the control map. Judgment is made and a judgment result “1” is output. Otherwise, the determination result “0” is output.

  On the other hand, in the process in which the outdoor heat exchanger temperature Ts rises, when the reference temperature BH is higher than the reference temperature B, it is determined that there is no risk of frost formation in the outdoor heat exchanger 20, and the determination The result “0” is output. Otherwise, the determination result “1” is output. If the determination result is “1”, the process proceeds to step S24. On the other hand, if the determination result is “0”, the process proceeds to step S26.

  In step S24, temperature difference determination is executed based on the above-described outside air temperature Tam, outdoor heat exchanger temperature Ts, and the control map shown in step S24 of FIG. That is, the progress of frost formation in the outdoor heat exchanger 20 is determined based on the temperature difference calculated by subtracting the outdoor heat exchanger temperature Ts from the outside air temperature Tam and the control map. Also in the control map shown in step S24, a hysteresis width for preventing control hunting (that is, the width of the reference temperature difference C to the reference temperature difference CH) is set.

  Specifically, in the temperature difference determination, first, the current temperature difference is calculated based on the current outside air temperature Tam detected by the outside air temperature sensor 42 and the third refrigerant temperature sensor 45c and the outdoor heat exchanger temperature Ts. . Then, by determining whether or not the calculated temperature difference is greater than a predetermined reference value, it is determined whether or not frost formation in the outdoor heat exchanger 20 has progressed to a predetermined stage.

  Note that the predetermined stage in the present invention means, for example, that the amount of frost formation on the outdoor heat exchanger 20 needs to stop the air conditioning operation and perform the defrosting operation in order to defrost the outdoor heat exchanger 20. It is a state less than the amount of frost formation.

  More specifically, in the process of decreasing the calculated temperature difference, frost formation in the outdoor heat exchanger 20 proceeds to a predetermined stage when the reference temperature difference C is equal to or less than that specified in the control map. It is determined that there is not, and a determination result “0” is output. Otherwise, the determination result “1” is output.

  On the other hand, in the process in which the calculated temperature difference increases, when the reference temperature difference CH is greater than the reference temperature difference C, the frost formation in the outdoor heat exchanger 20 has progressed from a predetermined stage. And the determination result “1” is output. Otherwise, the determination result “0” is output. If the determination result is “1”, the process proceeds to step S25. On the other hand, if the determination result is “0”, the process proceeds to step S26.

  In step S25, since frost formation in the outdoor heat exchanger 20 has progressed to some extent, dryness control is executed as a control mode of the first expansion valve 14a in the heating mode. This is because if the frosting of the outdoor heat exchanger 20 proceeds to some extent, the heat absorption amount in the outdoor heat exchanger 20 decreases, so that the heating capacity of the vehicle air conditioner 1 decreases.

  The dryness control is executed to compensate for a decrease in heating capacity caused by frost formation on the outdoor heat exchanger 20 even if the cycle efficiency (ie, COP) is deteriorated, and the throttle opening degree of the first expansion valve 14a is controlled. By controlling the refrigerant at the outlet side of the indoor condenser 12 to a gas-liquid two-phase state.

  Specifically, the air conditioning control device 40 adjusts the throttle opening of the first expansion valve 14a so that the high-pressure side refrigerant pressure Ph detected by the refrigerant pressure sensor 46 approaches the target high-pressure TPh, thereby condensing the room. The dryness of the refrigerant on the outlet side of the vessel 12 is controlled.

  Here, the target high pressure TPh is, for example, based on the target blowing temperature TAO determined in step S3, referring to a control map stored in advance in the air conditioning control device 40, and the blown air becomes the target blowing temperature TAO. To be determined.

  In the dryness control according to this step S25, the dryness of the refrigerant flowing out from the indoor condenser 12 is increased by increasing the throttle opening of the first expansion valve 14a. Thereby, at the time of heating mode, the flow volume (namely, gas injection amount) of the gaseous-phase refrigerant | coolant which flows in into the intermediate pressure port 11b of the compressor 11 can be increased.

  That is, according to the vehicle air conditioner 1 according to the first embodiment, the refrigerant on the outlet side of the indoor condenser 12 is controlled in the dryness degree in the heating mode, thereby decreasing due to the progress of frost formation in the outdoor heat exchanger 20. The amount of heat released from the indoor condenser 12 can be supplemented by the high-pressure side refrigerant circulation amount of the cycle through the intermediate pressure port 11 b and the compression work amount of the compressor 11.

  In step S26, frosting of the outdoor heat exchanger 20 has not progressed, and in order to perform the heating operation with good cycle efficiency in a state where the heating capacity of the vehicle air conditioner 1 can be sufficiently secured, As a control mode of the first expansion valve 14a in the heating mode, supercooling degree control is executed.

  Supercooling degree control is control for making the refrigerant | coolant in the exit side of the indoor condenser 12 into the liquid phase state which has a supercooling degree by controlling the opening degree of the 1st expansion valve 14a. Specifically, the air conditioning control device 40 adjusts the throttle opening of the first expansion valve 14a so that the degree of supercooling SC on the outlet side of the indoor condenser 12 approaches the target degree of supercooling TSC.

  Here, the degree of supercooling SC is defined as the absolute value of the temperature difference between the current temperature of the liquid-phase refrigerant and the saturated liquid refrigerant having the same pressure. The supercooling degree SC of the refrigerant at the present time depends on the outlet side refrigerant temperature Th detected by the second refrigerant temperature sensor 45b, the high pressure side refrigerant pressure Ph detected by the refrigerant pressure sensor 46, and the physical properties of the refrigerant circulating in the cycle. Calculated based on

  The target supercooling degree TSC is determined so that the cycle efficiency (COP) is maximized based on the temperature and pressure of the refrigerant flowing out on the outlet side of the indoor condenser 12. That is, the air conditioning control device 40 is specified based on the outlet-side refrigerant temperature Th detected by the second refrigerant temperature sensor 45b and the high-pressure side refrigerant pressure Ph detected by the refrigerant pressure sensor 46.

  In the supercooling degree control according to this step S26, for example, by reducing the throttle opening of the first expansion valve 14a, the supercooling degree SC on the outlet side of the indoor condenser 12 is increased, and the outlet side refrigerant temperature Th or The high-pressure side refrigerant pressure Ph is reduced.

  That is, according to the vehicle air conditioner 1 according to the first embodiment, the opening degree of the first expansion valve 14a is adjusted by controlling the degree of supercooling of the refrigerant on the outlet side of the indoor condenser 12 in the heating mode. Thus, the degree of supercooling SC can be brought close to the target degree of supercooling TSC. Thereby, the vehicle air conditioner 1 can bring the cycle efficiency in the refrigeration cycle apparatus 10 close to the maximum, and can heat the passenger compartment with good cycle efficiency.

  Next, the state of the refrigerant when the heating operation is performed by the supercooling degree control in step S26 will be described in detail with reference to the Mollier diagram shown in FIG. The supercooling degree control is executed in a normal state where the frosting of the outdoor heat exchanger 20 has not progressed and the heating capacity of the vehicle air conditioner 1 has not decreased.

  First, as indicated by points a1 and a2, the high-pressure refrigerant discharged from the discharge port 11c of the compressor 11 flows into the indoor condenser 12, is blown from the blower 32, and passes through the indoor evaporator 23. Heat exchange with heat. Thereby, blowing air is heated.

  As shown at points a2 and a3, the refrigerant flowing out of the indoor condenser 12 is decompressed and expanded in an enthalpy manner until it becomes an intermediate pressure refrigerant at the throttled first expansion valve 14a.

  Thereafter, the intermediate pressure refrigerant decompressed by the first expansion valve 14 a is gas-liquid separated by the gas-liquid separator 16. As indicated by points a3 and a9, the gas-phase refrigerant separated by the gas-liquid separator 16 is compressed via the second refrigerant passage 18b because the second on-off valve 15b is in the open state. It flows into the intermediate pressure port 11b of the machine 11. As indicated by point a <b> 10, the intermediate pressure refrigerant that has flowed into the compressor 11 merges with the refrigerant discharged by the low-stage compression mechanism of the compressor 11 and is sucked into the high-stage compression mechanism of the compressor 11.

  On the other hand, as indicated by points a3 and a4, the liquid-phase refrigerant separated by the gas-liquid separator 16 flows into the fixed throttle 17 because the third on-off valve 15c is in a closed state. When flowing into the fixed throttle 17, the liquid refrigerant is decompressed and expanded in an enthalpy manner until it becomes a low-pressure refrigerant, as indicated by points a4 and a5.

  As indicated by points a5 and a6, the refrigerant flowing out of the fixed throttle 17 flows into the outdoor heat exchanger 20, exchanges heat with the outside air blown from the blower fan 20a, and absorbs heat from the outside air. And since the refrigerant | coolant which flowed out from the outdoor heat exchanger 20 has the 4th on-off valve 15d in the valve opening state, it flows into the accumulator 24 via the 4th refrigerant path 18d, and is separated into gas and liquid.

  The gas-phase refrigerant separated by the accumulator 24 is sucked from the suction port 11a of the compressor 11 and compressed again by the low-stage compression mechanism, as indicated by points a7 and a8. As described above, in the pressure increasing process in the compressor 11, the refrigerant flowing in from the intermediate pressure port 11b merges with the refrigerant discharged from the low-stage compression mechanism.

  On the other hand, the liquid-phase refrigerant separated by the accumulator 24 is stored in the accumulator 24 as surplus refrigerant that is not necessary for exhibiting the refrigeration capacity for which the cycle is required.

  The reason why the points a6 and a7 are different is that the pressure loss generated in the gas-phase refrigerant flowing through the refrigerant piping from the accumulator 24 to the suction port 11a of the compressor 11 and the gas-phase refrigerant absorbs heat from the outside (outside air). This represents the amount of heat absorbed. Therefore, in an ideal cycle, it is desirable that the points a6 and a7 match.

  Therefore, in the supercooling degree control in the heating operation mode, the heat of the high-temperature and high-pressure refrigerant discharged from the compressor 11 by the indoor condenser 12 is radiated to the blown air, and the heated indoor blown air enters the vehicle interior. Can be blown out. Thereby, heating of a vehicle interior is realizable. At this time, in the degree of supercooling control, as shown at a point a2, it is possible to control the effluent refrigerant on the outlet side of the indoor condenser 12 to be the supercooled liquid phase refrigerant, thereby making the cycle efficiency close to the maximum.

  Further, in the heating mode, the low-pressure refrigerant decompressed by the fixed throttle 17 is sucked from the suction port 11a of the compressor 11, and the intermediate-pressure refrigerant decompressed by the first expansion valve 14a is caused to flow into the intermediate pressure port 11b. This is combined with the refrigerant in the pressurization process. That is, the refrigeration cycle apparatus 10 can constitute a so-called gas injection cycle (economizer refrigeration cycle) in the heating mode.

  Accordingly, the refrigeration cycle apparatus 10 can cause the high-stage compression mechanism to suck the mixed refrigerant having a low temperature, and can improve the compression efficiency of the high-stage compression mechanism. Further, since the refrigeration cycle apparatus 10 can reduce the pressure difference between the suction refrigerant pressure and the discharge refrigerant pressure of both the low-stage compression mechanism and the high-stage compression mechanism in the compressor 11, Compression efficiency can be improved. As a result, the vehicle air conditioner 1 can improve the coefficient of performance COP during heating as the entire refrigeration cycle apparatus 10.

  As shown in FIG. 7, the coefficient of performance at the time of supercooling degree control is obtained by dividing the heating capacity Qsc at the time of supercooling degree control by the compressor power Lsc at the time of supercooling degree control. The heating capacity Qsc at the time of supercooling degree control corresponds to the enthalpy difference between the points a1 and a2.

  Next, the state of the refrigerant when the heating operation is performed by the dryness control in step S25 will be described in detail with reference to the Mollier diagram shown in FIG. The dryness control is executed in a state where the frosting of the outdoor heat exchanger 20 has progressed to some extent and the heating capacity of the vehicle air conditioner 1 is reduced.

  First, as shown at points b1 and b2, the high-pressure refrigerant discharged from the discharge port 11c of the compressor 11 flows into the indoor condenser 12, is blown from the blower 32, and passes through the indoor evaporator 23. Heat exchange with heat. Thereby, blowing air is heated. Then, the refrigerant flowing out of the indoor condenser 12 is decompressed and expanded in an enthalpy manner until it becomes an intermediate pressure refrigerant in the throttled first expansion valve 14a, as indicated by points b2 and b3.

  Here, in the dryness control, the throttle opening of the first expansion valve 14a is increased to increase the dryness of the refrigerant flowing out from the indoor condenser 12, so the state of the refrigerant flowing out from the indoor condenser 12 is It changes to the position of the point b2 and becomes a gas-liquid two-phase state. Furthermore, the refrigerant pressure (point b9 and the like) flowing into the intermediate pressure port 11b of the compressor 11 and the refrigerant pressure (point b1 and the like) discharged from the discharge port 11c of the compressor 11 are compared with those during the supercooling degree control. To rise.

  Therefore, the temperature of the refrigerant discharged from the compressor 11 is increased with respect to the supercooling degree control, and the temperature difference between the temperature of the high-pressure refrigerant flowing through the indoor condenser 12 and the blown air flowing into the indoor condenser 12 is determined. While being able to expand, the gaseous-phase refrigerant | coolant flow volume (gas injection amount) which flows in from the intermediate pressure port 11b of the compressor 11 can be increased. As a result, the heating capacity of the blown air in the indoor condenser 12 can be improved during the dryness control compared to the supercooling control.

  Thereafter, the intermediate pressure refrigerant decompressed by the first expansion valve 14 a is gas-liquid separated by the gas-liquid separator 16. As indicated by points b3 and b9, the gas-phase refrigerant separated by the gas-liquid separator 16 flows into the intermediate pressure port 11b of the compressor 11 through the second refrigerant passage 18b. As indicated by a point b <b> 10, the intermediate pressure refrigerant that has flowed into the compressor 11 merges with the refrigerant discharged by the low-stage compression mechanism of the compressor 11 and is sucked into the high-stage compression mechanism of the compressor 11.

  As shown at points b3 and b4, the liquid-phase refrigerant separated by the gas-liquid separator 16 flows into the fixed throttle 17, and is isenthalpy until it becomes a low-pressure refrigerant as shown at points b4 and b5. Inflated to a reduced pressure.

  As indicated by points b5 and b6, the refrigerant flowing out of the fixed throttle 17 flows into the outdoor heat exchanger 20, exchanges heat with the outside air blown from the blower fan 20a, and absorbs heat from the outside air. Since the outdoor heat exchanger 20 in this case is frosted to some extent, the heat absorption amount is lower than that in a normal state (for example, when the superheat degree control is executed), and heating in the refrigeration cycle apparatus 10 is performed. This is a factor that reduces the ability.

  The refrigerant that has flowed out of the outdoor heat exchanger 20 flows into the accumulator 24 through the fourth refrigerant passage 18d and is separated into gas and liquid. The gas-phase refrigerant separated by the accumulator 24 is sucked from the suction port 11a of the compressor 11 and compressed again by the low-stage compression mechanism, as indicated by points b7 and b8. On the other hand, the liquid-phase refrigerant separated by the accumulator 24 is stored in the accumulator 24 as an excess refrigerant.

  The reason why the point b6 and the point b7 are different is that the pressure loss generated in the gas-phase refrigerant flowing through the refrigerant pipe from the accumulator 24 to the intake port 11a of the compressor 11 This represents the amount of heat absorbed by the phase refrigerant from outside (outside air).

  Here, the coefficient of performance at the time of dryness control is obtained by dividing the heating capacity Qd at the time of dryness control by the compressor power Ld at the time of dryness control. As shown in FIG. 8, the heating capability Qd at the time of dryness control corresponds to the enthalpy difference between the points b1 and b2, and is lower than the heating capability Qsc at the time of supercooling control. Further, the compressor power Ld at the time of dryness control is larger than the compressor power Lsc at the time of supercooling control. As a result, the coefficient of performance during dryness control is smaller than the coefficient of performance during supercooling control.

  However, according to this refrigeration cycle apparatus 10, a decrease in heating capacity due to frost formation in the outdoor heat exchanger 20 is suppressed by an increase in the circulation amount of high-pressure refrigerant in the cycle and the compression work amount accompanying execution of dryness control. can do.

  As described above, according to the refrigeration cycle apparatus 10 according to the first embodiment, in the heating mode, as shown in FIG. 3, the discharge port 11c of the compressor 11 → the indoor condenser 12 → the first expansion valve 14a → The refrigerant circulates in the order of the gas-phase refrigerant outlet of the gas-liquid separator 16 → the intermediate pressure port 11 b of the compressor 11, and the liquid-phase refrigerant outlet of the gas-liquid separator 16 → the fixed throttle 17 → the outdoor heat exchanger 20 → the accumulator 24. → A so-called gas injection cycle in which the refrigerant circulates in the order of the suction port 11a of the compressor 11 is configured.

  And according to the said refrigeration cycle apparatus 10, when a certain amount of frost occurs in the outdoor heat exchanger 20 and the heat absorption amount in the outdoor heat exchanger 20 is reduced, the opening degree of the first expansion valve 14a Is adjusted to control the dryness of the refrigerant on the outlet side of the indoor condenser 12.

  As a result, the flow rate of the gas-phase refrigerant separated in the gas-liquid separator 16 and flowing into the intermediate pressure port 11b of the compressor 11 can be increased, so that the amount of high-pressure side refrigerant circulation in the cycle increases and the amount of compression work Moreover, the fall of the heating capability which makes the factor the fall of the heat absorption amount of the outdoor heat exchanger 20 by frost formation can be suppressed.

  Moreover, in this refrigeration cycle apparatus 10, dryness control is realized by controlling the throttle opening of the first expansion valve 14a by the decompression device control unit 40b, and the heating capacity is reduced due to frost formation of the outdoor heat exchanger 20. Suppressed. Therefore, the refrigeration cycle apparatus 10 can cope with a decrease in heating capacity without complicating the cycle.

  And the refrigeration cycle apparatus 10 which concerns on 1st Embodiment adjusts the throttle opening of the 1st expansion valve 14a, when it determines with the frost formation of the outdoor heat exchanger 20 not progressing to the predetermined step. By doing this, the refrigerant on the outlet side of the indoor condenser 12 is undercooled. In the heating operation in the case where the outdoor heat exchanger 20 is not frosted to a predetermined stage by the supercooling degree control in step S26, the vehicle interior can be heated with good cycle efficiency.

  Further, the refrigeration cycle apparatus 10 has a supercooling degree control capable of realizing good cycle efficiency according to the progress of frost formation in the outdoor heat exchanger 20, and a heating capacity caused by frost formation although the cycle efficiency is deteriorated. Therefore, it is possible to properly use the dryness control capable of suppressing the decrease in the air conditioner, and the convenience as the vehicle air conditioner 1 can be enhanced.

  And according to the refrigeration cycle apparatus 10, in the dryness control, the throttle opening degree of the first expansion valve 14a is increased, and the dryness of the refrigerant flowing out from the indoor condenser 12 is increased. The dryness of the refrigerant on the outlet side of the indoor condenser 12 can be controlled, and the flow rate of the gas-phase refrigerant flowing into the intermediate pressure port 11b of the compressor 11 can be controlled.

  In addition, according to the refrigeration cycle apparatus 10, the determination process of step S22 and step S23 is executed using the outside air temperature Tam of the outside air temperature sensor 42 and the outdoor heat exchanger temperature Ts of the third refrigerant temperature sensor 45c. The frost formation state of the outdoor heat exchanger 20 can be determined with high accuracy. Therefore, the refrigeration cycle apparatus 10 can perform dryness control in accordance with the time when the heating capacity decreases due to frost formation of the outdoor heat exchanger 20, and can suppress the decrease in heating capacity at an appropriate timing. it can.

  Furthermore, according to the said refrigeration cycle apparatus 10, since the determination process of step S24 is performed using the temperature difference between the outdoor temperature Tam and the outdoor heat exchanger temperature Ts, the frosting state of the outdoor heat exchanger 20 is further increased. It can be determined with accuracy. Therefore, the refrigeration cycle apparatus 10 can perform dryness control in accordance with the time when the heating capacity decreases due to frost formation of the outdoor heat exchanger 20, and further suppress the decrease in heating capacity at an appropriate timing. Can do.

(Second Embodiment)
Next, a second embodiment different from the first embodiment described above will be described with reference to the drawings. The vehicle air conditioner 1 according to the second embodiment has basically the same configuration as that of the first embodiment except for the contents of a subroutine executed in the heating mode. Accordingly, in the following description, the same reference numerals as those in the first embodiment indicate the same configuration, and the preceding description is referred to.

  Hereinafter, the point in which the vehicle air conditioner 1 which concerns on 2nd Embodiment is different from 1st Embodiment is demonstrated, referring FIG. Also in the vehicle air conditioner 1 according to the second embodiment, the air conditioning controller 40 determines the frost formation state of the outdoor heat exchanger 20 in the heating mode, and according to the determination result, the supercooling degree control, Use dryness control properly. Specifically, the air conditioning control device 40 realizes this function by executing a subroutine according to FIG. 9 instead of the subroutine shown in FIG.

  As shown in FIG. 9, first, in step S31, as in step S21 in the first embodiment, it is determined whether or not the current operation mode is the heating mode. When it determines with it being heating mode, it progresses to step S32. On the other hand, if it is determined not to be in the heating mode, this subroutine is terminated as it is.

  In step S32, fan power consumption determination is executed based on the power consumption of the blower fan 20a and the control map shown in step S32 of FIG. That is, the progress of frost formation in the outdoor heat exchanger 20 is determined based on the power consumption of the blower fan 20a that blows air to the outdoor heat exchanger 20 and the control map. Also in the control map shown in step S32, a hysteresis width for preventing control hunting (that is, the width of the reference power consumption D to the reference power consumption DH) is set.

  As described above, the blower fan 20a is a brushless electric fan, and is arranged to blow air to the outdoor heat exchanger 20. Here, when frost formation of the outdoor heat exchanger 20 progresses and the ventilation resistance increases, even when a control signal instructing the same blowing capacity is input to the blowing fan 20a, the power consumption in the blowing fan 20a is reduced. descend. That is, in the second embodiment, the progress of frost formation in the outdoor heat exchanger 20 is detected and determined as a change in power consumption in the blower fan 20a via the ventilation resistance in the outdoor heat exchanger 20.

  Specifically, in the fan power consumption determination in step S32, it is determined whether or not the power consumption of the blower fan 20a is greater than a predetermined reference value. More specifically, in the process of reducing the power consumption of the blower fan 20a, frost formation in the outdoor heat exchanger 20 is performed at a predetermined stage when the power consumption becomes equal to or less than the reference power consumption D defined in the control map. It is determined that the process has not progressed until the determination result “0” is output. Otherwise, the determination result “1” is output.

  On the other hand, in the process of increasing the power consumption amount of the blower fan 20a, when the reference power consumption amount DH is larger than the reference power consumption amount D, the frost formation in the outdoor heat exchanger 20 is more than the predetermined stage. It determines with progressing, and outputs determination result "1". Otherwise, the determination result “0” is output. If the determination result is “1”, the process proceeds to step S33. On the other hand, if the determination result is “0”, the process proceeds to step S34.

  In step S33, since the frost formation in the outdoor heat exchanger 20 has progressed to some extent, the dryness control is performed as the control mode of the first expansion valve 14a in the heating mode, similarly to step S25 in the first embodiment. Execute.

  The dryness control is executed to compensate for a decrease in heating capacity caused by frost formation on the outdoor heat exchanger 20 even if the cycle efficiency (ie, COP) is deteriorated, and the throttle opening degree of the first expansion valve 14a is controlled. By controlling the refrigerant at the outlet side of the indoor condenser 12 to a gas-liquid two-phase state.

  Specifically, the air conditioning control device 40 adjusts the throttle opening of the first expansion valve 14a so that the high-pressure side refrigerant pressure Ph detected by the refrigerant pressure sensor 46 approaches the target high-pressure TPh, thereby condensing the room. The dryness of the refrigerant on the outlet side of the vessel 12 is controlled.

  That is, according to the vehicle air conditioner 1 according to the second embodiment, the refrigerant on the outlet side of the indoor condenser 12 is controlled to dryness in the heating mode, so that it decreases with the progress of frost formation in the outdoor heat exchanger 20. The amount of heat released from the indoor condenser 12 can be supplemented by the high-pressure side refrigerant circulation amount of the cycle through the intermediate pressure port 11 b and the compression work amount of the compressor 11.

  In step S34, the frosting of the outdoor heat exchanger 20 has not progressed, and in order to perform the heating operation with good cycle efficiency in a state where the heating capacity of the vehicle air conditioner 1 can be sufficiently secured, As a control mode of the first expansion valve 14a in the heating mode, supercooling degree control is executed.

  This supercooling degree control is the same as step S26 in the first embodiment, and the refrigerant on the outlet side of the indoor condenser 12 has a supercooling degree by controlling the throttle opening of the first expansion valve 14a. This is a control for setting the liquid phase. Specifically, the air conditioning control device 40 adjusts the throttle opening of the first expansion valve 14a so that the degree of supercooling SC on the outlet side of the indoor condenser 12 approaches the target degree of supercooling TSC.

  That is, according to the vehicle air conditioner 1 according to the second embodiment, the opening degree of the first expansion valve 14a is adjusted by controlling the degree of supercooling of the refrigerant on the outlet side of the indoor condenser 12 in the heating mode. Thus, the degree of supercooling SC can be brought close to the target degree of supercooling TSC. Thereby, the vehicle air conditioner 1 can bring the cycle efficiency in the refrigeration cycle apparatus 10 close to the maximum, and can heat the passenger compartment with good cycle efficiency.

  As described above, according to the refrigeration cycle apparatus 10 according to the second embodiment, the gas injection cycle is configured in the heating mode, similarly to the first embodiment. Further, according to the refrigeration cycle apparatus 10, when the frost formation to some extent occurs in the outdoor heat exchanger 20 and the heat absorption amount in the outdoor heat exchanger 20 is reduced, the opening degree of the first expansion valve 14a. The refrigerant on the outlet side of the indoor condenser 12 is controlled to dryness.

  As a result, the refrigeration cycle apparatus 10 according to the second embodiment is also separated in the gas-liquid separator 16, and the flow rate of the gas-phase refrigerant flowing into the intermediate pressure port 11b of the compressor 11 can be increased. A decrease in heating capacity caused by a decrease in the amount of heat absorbed by the outdoor heat exchanger 20 due to frost formation can be suppressed by increasing the circulation amount of the high-pressure side refrigerant and the amount of compression work.

  Moreover, in this refrigeration cycle apparatus 10, dryness control is realized by controlling the throttle opening of the first expansion valve 14a by the decompression device control unit 40b, and the heating capacity is reduced due to frost formation of the outdoor heat exchanger 20. Suppressed. Therefore, the refrigeration cycle apparatus 10 can cope with a decrease in heating capacity without complicating the cycle.

  The refrigeration cycle apparatus 10 according to the second embodiment controls the degree of supercooling of the refrigerant at the outlet side of the indoor condenser 12 when it is determined that the frosting of the outdoor heat exchanger 20 has not progressed to a predetermined stage. By doing so, the vehicle interior can be heated with good cycle efficiency.

  Further, the refrigeration cycle apparatus 10 can selectively use the dryness control in step S25 and the supercooling degree control in step S26 according to the progress of frost formation in the outdoor heat exchanger 20, so that the vehicle air conditioner The convenience as 1 can be improved.

  According to the refrigeration cycle apparatus 10 according to the second embodiment, in the dryness control, the throttle opening of the first expansion valve 14a is increased, and the dryness of the refrigerant flowing out from the indoor condenser 12 is increased. Therefore, the dryness of the refrigerant on the outlet side of the indoor condenser 12 can be controlled with high accuracy, and the flow rate of the gas-phase refrigerant flowing into the intermediate pressure port 11b of the compressor 11 can be controlled.

  Furthermore, according to the refrigeration cycle apparatus 10, the determination process of step S32 is executed using the power consumption of the blower fan 20a, so that the frosting condition of the outdoor heat exchanger 20 can be determined with higher accuracy. it can. Therefore, the refrigeration cycle apparatus 10 can perform dryness control in accordance with the time when the heating capacity decreases due to frost formation of the outdoor heat exchanger 20, and further suppress the decrease in heating capacity at an appropriate timing. Can do.

(Other embodiments)
As mentioned above, although this invention was demonstrated based on embodiment, this invention is not limited to embodiment mentioned above at all. That is, various improvements and modifications can be made without departing from the spirit of the present invention. For example, the above-described embodiments may be combined as appropriate, and the above-described embodiments may be variously modified.

  (1) In the above-described embodiment, the second on-off valve 15b, the third on-off valve 15c, the gas-liquid separator 16, the fixed throttle 17, and the third refrigerant passage 18c are individually configured. It is not limited to. For example, it is also possible to employ an integrated valve in which each configuration of the second on-off valve 15b to the third refrigerant passage 18c described above is unitized with one body portion. And the structure unitized as an integrated valve is not limited to the above-mentioned example, It can change suitably.

  (2) In the above-described embodiment, the second on-off valve 15b is an electromagnetic that opens and closes the second refrigerant passage 18b that connects the gas-phase refrigerant outlet of the gas-liquid separator 16 and the intermediate pressure port 11b of the compressor 11. Although it was set as the valve, it is not limited to this aspect. For example, instead of the second on-off valve 15b, a differential pressure valve that opens and closes the second refrigerant passage 18b can be arranged.

  (3) Moreover, when it transfers to step S25 and step S33 and performs heating operation by dryness control, "Because frost formation of the outdoor heat exchanger 20 is advancing, a defrost operation is required. It is also possible to notify the occupant of “the effect” or “the current heating operation is in a state of low cycle efficiency”. Thereby, the passenger | crew can take an appropriate measure according to the present condition with respect to the frost formation of the outdoor heat exchanger 20 which advanced to the predetermined stage.

  (4) Moreover, although the refrigerating cycle apparatus 10 which concerns on each above-mentioned embodiment was comprised so that a cooling operation, heating operation, serial dehumidification heating operation, and parallel dehumidification heating operation were switchable, it is limited to this aspect. is not. For example, in addition to each operation mode in the above-described embodiment, it is possible to be configured to be switchable to the defrosting operation mode.

  (5) And as dehumidification heating operation in each above-mentioned embodiment, the dehumidification heating operation by the refrigerating cycle by which an outdoor heat exchanger and an indoor evaporator are connected in series with respect to a refrigerant flow, an outdoor heat exchanger, The indoor evaporator is configured to be switchable between the dehumidifying and heating operation by a refrigeration cycle connected in parallel to the refrigerant flow, but is not limited to this mode. Only one of the series dehumidifying and heating operation and the parallel dehumidifying and heating operation can be executed.

  (6) In each of the above-described embodiments, the example in which each operation mode is switched by executing the air conditioning control program has been described. However, the switching of each operation mode is not limited to this. For example, each operation mode may be switched with reference to a control map stored in advance in the air conditioning control device based on the target blowing temperature and the outside air temperature.

  In addition, an operation mode setting switch for setting each operation mode may be provided on the operation panel, and the cooling mode, the dehumidifying heating mode, and the heating mode may be switched according to an operation signal of the operation mode setting switch.

DESCRIPTION OF SYMBOLS 10 Refrigeration cycle apparatus 11 Compressor 12 Indoor condenser 14a 1st expansion valve 16 Gas-liquid separator 17 Fixed throttle 18b 2nd refrigerant | coolant path 20 Outdoor heat exchanger 40 Air-conditioning control apparatus 40b Pressure reduction apparatus control part

Claims (6)

An intermediate pressure port (which compresses the low-pressure refrigerant sucked from the suction port (11a) until it becomes high-pressure refrigerant and discharges it from the discharge port (11c). A compressor (11) having 11b);
A radiator (12) for exchanging heat between the high-pressure refrigerant discharged from the discharge port (11c) and the heat exchange target fluid;
A high-stage decompression section (14a) that depressurizes the high-pressure refrigerant flowing out of the radiator (12) and adjusts the degree of supercooling or dryness of the refrigerant on the outlet side of the radiator (12);
A gas-liquid separation unit (16) that separates the gas-liquid of the refrigerant that has been depressurized to become an intermediate pressure refrigerant in the high-stage depressurization unit (14a);
An intermediate pressure refrigerant passage (18b) for guiding the gas-phase refrigerant separated in the gas-liquid separation section (16) to the intermediate pressure port (11b) side;
A low-stage decompression unit (17) for decompressing the liquid-phase refrigerant separated in the gas-liquid separation unit (16) until the low-pressure refrigerant is obtained;
An outdoor heat exchanger (20) for exchanging heat of the refrigerant decompressed in the low-stage decompression section (17) with the outside air and flowing it out to the upstream side of the suction port (11a);
A decompression control section (40b) for controlling the operation of the high stage decompression section (14a);
A frost condition determination unit (S22, S23, S24, S32) for determining whether or not the frost condition in the outdoor heat exchanger has progressed to a predetermined stage,
When it is determined that the frosting state in the outdoor heat exchanger (20) has progressed to a predetermined stage, the decompression control unit (40b) adjusts the opening of the high stage decompression unit (14a). And the refrigerating-cycle apparatus which makes dryness control the refrigerant | coolant in the exit side of the said heat radiator (12).   When it is determined that the frosting state in the outdoor heat exchanger (20) has not progressed to a predetermined stage, the decompression control unit (40b) adjusts the opening degree of the high-stage decompression unit (14a). And the refrigerating-cycle apparatus of Claim 1 which makes supercooling degree control the refrigerant | coolant in the exit side of the said heat radiator (12).   The said pressure reduction control part (40b) increases the dryness of the refrigerant | coolant in the exit side of the said heat radiator (12) with the increase in the opening degree of the said high stage pressure reduction part (14a). The refrigeration cycle apparatus described. An environmental temperature detector (42) for detecting the environmental temperature of the outdoor heat exchanger (20);
A temperature detector (45c) for detecting the outlet side refrigerant temperature of the outdoor heat exchanger (20),
The frost formation state determination unit (S22, S23, S24) uses the environmental temperature and the outlet side refrigerant temperature to confirm that the frost formation state in the outdoor heat exchanger (20) has progressed to a predetermined stage. The refrigeration cycle apparatus according to any one of claims 1 to 3, wherein a determination is made.   When the difference between the environmental temperature and the outlet-side refrigerant temperature is smaller than a predetermined reference temperature difference, the frost formation state determination unit (S24) determines the frost formation state in the outdoor heat exchanger (20). The refrigeration cycle apparatus according to claim 4, wherein the refrigeration cycle apparatus is determined to have progressed to a predetermined stage. A blower fan (20a) for blowing the outside air to the outdoor heat exchanger (20),
The frosting state determination unit (S32) has progressed to a predetermined stage in the frosting state in the outdoor heat exchanger when the power consumption amount of the blower fan is larger than a predetermined reference power consumption amount. The refrigeration cycle apparatus according to any one of claims 1 to 3, wherein the refrigeration cycle apparatus is determined.

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