JP2016176609A - Refrigeration cycle device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a refrigeration cycle device preventing liquid refrigerant from accumulating in a condenser, in a situation where a compressor is intermittently operated.SOLUTION: A controller 50, when it is necessary to drive a compressor 11 at a rotational frequency that is a lower limit rotational frequency or more, performs continuous operation control of continuously driving the compressor 11; when it is necessary to drive the compressor 11 at a rotational frequency that is lower than the lower limit rotational frequency, performs intermittent operation control of repeating drive and stop of the compressor 11; and when performing the intermittent operation control, controls operation of a cross sectional area change mechanism of an expansion valve 14 so that a lower limit value of a cross sectional area of a refrigerant passage of the expansion valve 14 is made larger than that in a case of performing the continuous operation control.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a refrigeration cycle apparatus including a compressor that sucks and discharges refrigerant and a control unit that intermittently operates the compressor.

  Conventionally, Patent Document 1 discloses a vehicle air conditioner that includes a condenser that condenses high-pressure refrigerant in a refrigeration cycle and an expansion valve that decompresses and expands the refrigerant condensed in the condenser. Adjust the rotation speed of the compressor so that the pressure of the refrigerant exiting the compressor approaches the target high pressure, and adjust the opening of the expansion valve so that the degree of supercooling of the refrigerant flowing into the expansion valve approaches the target degree of supercooling. A vehicle air conditioner to be adjusted is described.

  Conventionally, Patent Document 2 describes an air conditioner that performs intermittent operation that repeats driving and stopping of a compressor when the rotational speed of the compressor is desired to be lower than the lower limit rotational speed.

  That is, the compressor cannot be driven at a rotational speed lower than a predetermined lower limit rotational speed because of the driving torque. When it is desired to drive the compressor at a rotational speed lower than the lower limit rotational speed, an operation corresponding to a rotational speed lower than the lower limit rotational speed can be obtained by performing intermittent operation in which the compressor is driven and stopped repeatedly.

JP 2014-94677 A JP-A-8-14632

  When the compressor is intermittently operated as in the prior art of Patent Document 2, when the degree of supercooling is controlled by the expansion valve as in the prior art of Patent Document 1, the opening degree of the expansion valve becomes too small. The liquid refrigerant may stay in the condenser, the temperature of the air blown out from the condenser may decrease, or the temperature distribution of the air blown out from the condenser may deteriorate.

  That is, when the compressor is intermittently operated, the refrigerant flows intermittently, so that the refrigerant condensed in the condenser tends to stay. Therefore, since the flow rate of the refrigerant flowing from the condenser to the expansion valve decreases, it becomes difficult to accurately detect the degree of supercooling of the refrigerant flowing into the expansion valve with a sensor. As a result, the opening degree of the expansion valve tends to be too small.

  When the opening degree of the expansion valve becomes too small, the refrigerant flow is too narrowed by the expansion valve, and the high pressure of the refrigeration cycle rises rapidly. Then, since the high pressure becomes too higher than the target high pressure, the compressor stop time becomes long. For this reason, a vicious cycle occurs in which the liquid refrigerant stays more conspicuous in the condenser.

  If the liquid refrigerant stays in the condenser, heat cannot be sufficiently exchanged in the portion where the liquid refrigerant stays, so that temperature distribution occurs and the refrigerant heat dissipation performance decreases.

  In the case of an air conditioner that heat-exchanges refrigerant and air with a condenser and blows it out into the passenger compartment, there is a risk that temperature distribution will occur in the blown air and the temperature of the blown air will drop, deteriorating passenger comfort.

  In the case of an air conditioner that heat-exchanges low-pressure refrigerant and air in the refrigeration cycle evaporator and blows out into the passenger compartment, if the liquid refrigerant stays in the condenser, the flow rate of the refrigerant flowing into the evaporator is insufficient. There is a possibility that the temperature distribution is generated and the temperature of the blown air is lowered, thereby deteriorating passenger comfort.

  In view of the above points, an object of the present invention is to prevent liquid refrigerant from staying in a condenser in a situation where a compressor is operated intermittently.

In order to achieve the above object, in the invention described in claim 1,
A compressor (11) for compressing and discharging the refrigerant;
Condensers (12, 15) for radiating the refrigerant discharged from the compressor (11) to condense the refrigerant;
Cross-sectional area changing mechanisms (14b, 14e, 19b) that change the cross-sectional areas of the refrigerant passages (14a, 14d, 19a) through which the refrigerant condensed in the condensers (12, 15) flows and the refrigerant passages (14a, 14d, 19a). ), And decompression means (14, 19) for decompressing the refrigerant condensed in the condenser (12),
An evaporator (20) for absorbing the heat of the refrigerant decompressed by the decompression means (14, 19) and evaporating the refrigerant;
Control means (50) for controlling the operation of the compressor (11) and the cross-sectional area changing mechanism (14b, 14e, 19b),
The control means (50)
When it is necessary to drive the compressor (11) at a rotational speed equal to or higher than the lower limit rotational speed, continuous operation control for continuously driving the compressor (11) is performed,
When it is necessary to drive the compressor (11) at a rotational speed lower than the lower limit rotational speed, intermittent operation control for repeating the driving and stopping of the compressor (11) is performed,
When performing intermittent operation control, the cross-sectional area changing mechanism (14b, 14e, so that the lower limit value of the cross-sectional area of the refrigerant passages (14a, 14d, 19a) is larger than when performing continuous operation control. The operation of 19b) is controlled.

  According to this, when the compressor (11) is intermittently operated, the decompression means (14, 19) is provided in the refrigerant passages (14a, 14d, 19a) as compared with the case where the compressor (11) is continuously operated. It is possible to suppress the refrigerant flow from being too narrow by making the cross-sectional area too small. Therefore, it can suppress that a liquid refrigerant stagnates in a condenser (12, 15).

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

It is a schematic block diagram of the vehicle air conditioner which concerns on 1st Embodiment. It is sectional drawing which shows the 1st expansion valve of the vehicle air conditioner which concerns on 1st Embodiment. It is an operation characteristic figure of the 1st expansion valve concerning a 1st embodiment. It is a flowchart which shows the flow of the control processing which the control apparatus of the vehicle air conditioner which concerns on 1st Embodiment performs. It is a flowchart which shows the flow of the control processing at the time of the heating mode which the control apparatus of the vehicle air conditioner which concerns on 1st Embodiment performs. It is a control characteristic figure used when the control apparatus of the vehicle air conditioner which concerns on 1st Embodiment calculates the lower limit of an expansion valve instruction | indication opening degree. It is a Mollier diagram which shows the state of the refrigerant | coolant at the time of the 1st dehumidification heating mode (1st mode) in the refrigeration cycle apparatus which concerns on 1st Embodiment. It is a Mollier diagram which shows the state of the refrigerant | coolant at the time of the 1st dehumidification heating mode (at the time of 2nd mode) in the refrigerating-cycle apparatus which concerns on 1st Embodiment. It is a Mollier diagram which shows the state of the refrigerant | coolant at the time of the 1st dehumidification heating mode (at the time of 3rd mode) in the refrigerating-cycle apparatus which concerns on 1st Embodiment. It is a Mollier diagram which shows the state of the refrigerant | coolant at the time of the 1st dehumidification heating mode in the refrigeration cycle apparatus which concerns on 1st Embodiment (at the time of 4th mode). It is a Mollier diagram which shows the state of the refrigerant | coolant at the time of the 2nd dehumidification heating mode in the refrigerating-cycle apparatus which concerns on 1st Embodiment. It is a flowchart which shows the flow of the control processing at the time of the heating mode which the control apparatus of the vehicle air conditioner which concerns on 2nd Embodiment performs. It is a control characteristic figure used when the control apparatus of the vehicle air conditioner which concerns on 2nd Embodiment calculates the lower limit of an expansion valve instruction | indication opening degree. It is a flowchart which shows the flow of the control processing at the time of the heating mode which the control apparatus of the vehicle air conditioner which concerns on 3rd Embodiment performs. It is sectional drawing which shows the 1st expansion valve of the vehicle air conditioner which concerns on 3rd Embodiment. It is a flowchart which shows the flow of the control processing at the time of the heating mode which the control apparatus of the vehicle air conditioner which concerns on 4th Embodiment performs. It is a control characteristic figure used when the control apparatus of the vehicle air conditioner which concerns on 4th Embodiment calculates the lower limit of an expansion valve instruction | indication opening degree.

  Hereinafter, embodiments will be described with reference to the drawings. In the following embodiments, the same or equivalent parts are denoted by the same reference numerals in the drawings.

(First embodiment)
1st Embodiment of this invention is described based on FIGS. FIG. 1 is a schematic configuration diagram of a vehicle air conditioner 1 according to the present embodiment.

  In this embodiment, the refrigeration cycle apparatus 10 of the present invention is applied to a vehicle air conditioner 1 for a hybrid vehicle that obtains a driving force for vehicle travel from an internal combustion engine (engine) and a travel electric motor. The refrigeration cycle apparatus 10 functions to cool or heat the vehicle interior air blown into the vehicle interior, which is the air conditioning target space, in the vehicle air conditioner 1.

  For this reason, the refrigeration cycle apparatus 10 heats the refrigerant flow path in the cooling mode (cooling operation) for cooling the vehicle interior, the refrigerant flow path in the dehumidification heating mode (dehumidification operation) for heating while dehumidifying the vehicle interior, and the vehicle interior. The refrigerant flow path in the heating mode (heating operation) can be switched.

  In the refrigeration cycle apparatus 10, the first dehumidifying and heating mode that is executed during normal time and the second dehumidifying and heating mode that is executed when the outside air temperature is low can be executed as the dehumidifying and heating mode.

  In the refrigeration cycle apparatus 10 of the present embodiment, a normal chlorofluorocarbon refrigerant is used as the refrigerant, and a subcritical refrigeration cycle in which the pressure of the high-pressure refrigerant does not exceed the critical pressure of the refrigerant is configured. This refrigerant is mixed with refrigerating machine oil for lubricating the compressor 11, and a part of the refrigerating machine oil circulates in the cycle together with the refrigerant.

  The compressor 11 is disposed in an engine room (not shown), sucks refrigerant in the refrigeration cycle apparatus 10, compresses and discharges it, and electrically operates a fixed capacity type compression mechanism 11a having a fixed discharge capacity. This is an electric compressor driven by a motor 11b. Specifically, various compression mechanisms such as a scroll-type compression mechanism and a vane-type compression mechanism can be employed as the compression mechanism 11a.

  The operation (rotation speed) of the electric motor 11b is controlled by a control signal output from the control device 50, and either an AC motor or a DC motor may be adopted. And the refrigerant | coolant discharge capability of the compression mechanism 11a is changed by this rotation speed control. Therefore, in this embodiment, the electric motor 11b comprises the discharge capability change means of the compression mechanism 11a.

  The electric motor 11b is an AC motor whose operation (number of rotations) is controlled by the AC voltage output from the inverter 51. Electric power is supplied from the battery 52 to the inverter 51. Inverter 51 outputs an alternating voltage having a frequency corresponding to a control signal output from control device 50. And the refrigerant | coolant discharge capability of the compressor 11 is changed by this rotation speed control. Therefore, the electric motor 11b constitutes a discharge capacity changing unit of the compressor 11.

  The inlet side of the indoor condenser 12 is connected to the discharge port side of the compressor 11. The indoor condenser 12 is disposed in the casing 31 of the indoor air conditioning unit 30, dissipates the discharged refrigerant (high-pressure refrigerant) discharged from the compressor 11, and heats the vehicle interior blown air that has passed through the indoor evaporator 20. It is a radiator (heat exchanger for heating).

  A first refrigerant passage 13 that guides the refrigerant flowing out of the indoor condenser 12 to the outdoor heat exchanger 15 is connected to the outlet side of the indoor condenser 12. The first refrigerant passage 13 is provided with a first expansion valve (first throttle means) 14 configured to be able to change the passage area (throttle opening) of the first refrigerant passage 13.

  The first expansion valve 14 is a decompression unit that decompresses the refrigerant condensed by the indoor condenser 12. The first expansion valve 14 is an electric variable throttle mechanism. Specifically, as shown in FIG. 2, the first expansion valve 14 includes an expansion valve passage 14a, a valve body 14b, and an electric actuator 14c.

  The expansion valve passage 14 a is a refrigerant passage communicating with the first refrigerant passage 13. The valve body 14b is a cross-sectional area changing mechanism that changes the cross-sectional area of the expansion valve passage 14a. The electric actuator 14c is a valve body drive means including a stepping motor that changes the throttle opening of the valve body 14b.

  The first expansion valve 14 of the present embodiment is configured by a variable throttle mechanism with a fully open function that fully opens the first refrigerant passage 13 (specifically, the expansion valve passage 14a) when the throttle opening is fully opened. That is, the first expansion valve 14 can prevent the refrigerant from depressurizing by fully opening the first refrigerant passage 13. As shown in the operation characteristic diagram of FIG. 3, the operation (control opening degree, opening cross-sectional area) of the first expansion valve 14 is controlled by a control signal (instruction pulse) output from the control device 50.

  The inlet side of the outdoor heat exchanger 15 is connected to the outlet side of the first expansion valve 14. The outdoor heat exchanger 15 exchanges heat between the refrigerant circulating inside and the outside air blown from a blower fan (not shown). The outdoor heat exchanger 15 functions as an evaporator that evaporates the refrigerant and exerts an endothermic effect in the heating mode or the like, and functions as a radiator that radiates the refrigerant in the cooling mode or the like.

  On the outlet side of the outdoor heat exchanger 15, the second refrigerant passage 16 that guides the refrigerant flowing out of the outdoor heat exchanger 15 to the suction side of the compressor 11 through the accumulator 21, and the refrigerant flowing out of the outdoor heat exchanger 15. Is connected to the suction side of the compressor 11 via the indoor evaporator 20 and the accumulator 21.

  A first opening / closing valve (first opening / closing means) 17 is disposed in the second refrigerant passage 16. The first on-off valve 17 is an electromagnetic valve that opens and closes the second refrigerant passage 16, and its operation is controlled by a control signal output from the control device 50.

  When the first on-off valve 17 is open, the pressure loss that occurs when the refrigerant passes through the second refrigerant passage 16 is smaller than the pressure loss that occurs when the refrigerant passes through the third refrigerant passage 18. This is because the check valve 24 and the second expansion valve 19 are disposed in the third refrigerant passage 18. Therefore, the refrigerant that has flowed out of the outdoor heat exchanger 15 flows to the second refrigerant passage 16 side when the first on-off valve 17 is open, and third when the first on-off valve 17 is closed. It flows to the refrigerant passage 18 side.

  Thus, the 1st on-off valve 17 fulfill | performs the function which switches a cycle structure (refrigerant flow path) by opening and closing the 2nd refrigerant path 16. FIG. Therefore, the 1st on-off valve 17 comprises the refrigerant | coolant flow path switching means which switches the refrigerant | coolant flow path of the refrigerant | coolant which circulates through a cycle.

  The third refrigerant passage 18 is provided with a second expansion valve (second throttling means) 19 that can change the passage area (throttle opening).

  The second expansion valve 19 is a decompression unit that decompresses the refrigerant condensed in the outdoor heat exchanger 15. The second expansion valve 19 is an electric variable throttle mechanism. The basic configuration of the second expansion valve 19 is the same as that of the first expansion valve 14. Specifically, as shown in parentheses in FIG. 2, the second expansion valve 19 includes an expansion valve passage 19a, a valve body 19b, and an electric actuator 19c. The expansion valve passage 19 a is a refrigerant passage communicating with the third refrigerant passage 18. The valve body 19b is a cross-sectional area changing means that changes the cross-sectional area of the expansion valve passage 19a. The electric actuator 19c is a valve body drive means including a stepping motor that changes the throttle opening of the valve body 19b.

  The second expansion valve 19 of the present embodiment has a fully open function for fully opening the third refrigerant passage 18 when the throttle opening is fully opened, and a fully closed function for closing the third refrigerant passage 18 when the throttle opening is fully closed. It consists of a variable aperture mechanism with functions. That is, the second expansion valve 19 can prevent the refrigerant from depressurizing and can open and close the third refrigerant passage 18. The operation of the second expansion valve 19 is controlled by a control signal output from the control device 50.

  The inlet side of the indoor evaporator 20 is connected to the outlet side of the second expansion valve 19. The indoor evaporator 20 is arranged in the casing 31 of the indoor air conditioning unit 30 on the upstream side of the air flow in the vehicle interior of the indoor condenser 12. The indoor evaporator 20 evaporates the refrigerant circulating in the cooling mode and the dehumidifying heating mode by exchanging heat with the air blown into the passenger compartment before passing through the indoor condenser 12, thereby exhibiting an endothermic effect. It is a heat absorber (cooling heat exchanger) that cools the air blown into the passenger compartment.

  The outlet side of the indoor evaporator 20 is connected to the inlet side of the accumulator 21. The accumulator 21 is a gas-liquid separator that separates the gas-liquid refrigerant flowing into the accumulator 21 and stores excess refrigerant in the cycle. The suction port side of the compressor 11 is connected to the gas phase refrigerant outlet of the accumulator 21. Therefore, the accumulator 21 functions to prevent liquid phase refrigerant from being sucked into the compressor 11 and prevent liquid compression in the compressor 11.

  In the present embodiment, refrigerant in a range from the outlet side of the indoor condenser 12 in the first refrigerant passage 13 to the inlet side of the first expansion valve 14 is changed from the outlet side of the outdoor heat exchanger 15 in the third refrigerant passage 18 to the first refrigerant passage 13. A bypass passage 22 is provided that leads to a range leading to the inlet side of the two expansion valve 19. In other words, the bypass passage 22 is a refrigerant passage that guides the refrigerant flowing out of the indoor condenser 12 to the inlet side of the second expansion valve 19 by bypassing the first expansion valve 14 and the outdoor heat exchanger 15.

  A second opening / closing valve (second opening / closing means) 23 is disposed in the bypass passage 22. The second on-off valve 23 is an electromagnetic valve that opens and closes the bypass passage 22, and its operation is controlled by a control signal output from the control device 50.

  The second on-off valve 23 functions to switch the cycle configuration (refrigerant flow path) by opening and closing the bypass passage 22. Therefore, the second on-off valve 23 constitutes a refrigerant flow path switching means for switching the refrigerant flow path of the refrigerant circulating in the cycle together with the first on-off valve 17.

  In the present embodiment, a check valve (backflow prevention means) 24 is arranged between the outlet side of the outdoor heat exchanger 15 in the third refrigerant passage 18 and the junction of the bypass passage 22 and the third refrigerant passage 18. Yes. The check valve 24 allows the refrigerant to flow from the outlet side of the outdoor heat exchanger 15 to the inlet side of the second expansion valve 19, and from the inlet side of the second expansion valve 19 to the outlet side of the outdoor heat exchanger 15. The check valve 24 can prevent the refrigerant that has joined the bypass passage 22 and the third refrigerant passage 18 from flowing to the outdoor heat exchanger 15 side.

  Next, the indoor air conditioning unit 30 will be described. The indoor air-conditioning unit 30 is disposed inside the instrument panel (instrument panel) at the forefront of the vehicle interior, and the blower 32, the above-described indoor condenser 12, and the indoor evaporator 20 are disposed in a casing 31 that forms the outer shell of the interior air-conditioning unit 30. The heater core 34 and the like are accommodated.

  The casing 31 forms an air passage for the air blown into the passenger compartment, 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 for switching and introducing vehicle interior air (inside air) and outside air is arranged on the most upstream side of the blown air flow in the casing 31.

  The inside / outside air switching device 33 is formed with an inside air introduction port for introducing inside air into the casing 31 and an outside air introduction port for introducing outside air. Furthermore, inside / outside air switching device 33 is provided with an inside / outside air switching door that continuously adjusts the opening area of the inside air introduction port and the outside air introduction port to change the air volume ratio between the inside air volume and the outside air volume. Has been.

  A blower 32 that blows air introduced through the inside / outside air switching device 33 toward the vehicle interior is disposed on the downstream side of the air flow of the inside / outside air switching device 33. The blower 32 is an electric blower that drives a centrifugal multiblade fan (sirocco fan) 32a by an electric motor 32b, and the number of rotations (air flow rate) is controlled by a control signal (control voltage) output from the control device 50. Is done. The centrifugal multiblade fan 32a functions as a blowing unit that blows air into the passenger compartment.

  On the downstream side of the air flow of the blower 32, the indoor evaporator 20, the heater core 34, and the indoor condenser 12 are arranged in this order with respect to the flow of the air blown into the vehicle interior. In other words, the indoor evaporator 20 is disposed upstream of the indoor condenser 12 and the heater core 34 in the flow direction of the air blown into the vehicle interior.

  The heater core 34 is a heat exchanger for heating that exchanges heat between engine cooling water that outputs driving force for vehicle travel and air blown into the vehicle interior. The heater core 34 of the present embodiment is disposed upstream of the indoor condenser 12 in the flow direction of the air blown into the vehicle interior. In the casing 31, a cold air bypass passage 35 is formed in which the air that has passed through the indoor evaporator 20 is caused to bypass the indoor condenser 12 and the heater core 34.

  The air after passing through the indoor evaporator 20 passes through the indoor condenser 12 and the heater core 34 on the downstream side of the indoor evaporator 20 and on the upstream side of the indoor condenser 12 and the heater core 34. An air mix door 36 for adjusting the air volume ratio between the air to be passed and the air passing through the cold air bypass passage 35 is disposed. On the downstream side of the air flow of the indoor condenser 12 and the downstream side of the air flow of the cold air bypass passage 35, a mixing space for mixing the air that has passed through the indoor condenser 12 and the air that has passed through the cold air bypass passage 35 is provided. .

  Furthermore, the blower outlet (not shown) which blows the conditioned air mixed in the mixing space into the vehicle interior which is an air-conditioning target space is disposed on the most downstream side of the blast air flow in the casing 31. Specifically, as the air outlet, there are a face air outlet that blows air-conditioned air to the upper body of the passenger in the passenger compartment, a foot air outlet that blows air-conditioned air to the feet of the passenger, and a defroster that blows air-conditioned air toward the inner surface of the front window glass of the vehicle There is an air outlet.

  Therefore, by adjusting the air volume ratio between the air that the air mix door 36 passes through the indoor condenser 12 and the air that passes through the cold air bypass passage 35, the temperature of the conditioned air mixed in the mixing space is adjusted, The temperature of the conditioned air blown out from the air outlet is adjusted. The air mix door 36 is driven by a servo motor (not shown) that operates according to a control signal output from the control device 50.

  A face door (not shown) for adjusting the opening area of the face outlet and a foot door (not shown) for adjusting the opening area of the foot outlet are provided on the upstream side of the air flow of the face outlet, the foot outlet, and the defroster outlet. ) And a defroster door (not shown) for adjusting the opening area of the defroster outlet.

  These face doors, foot doors, and defroster doors constitute the outlet mode switching means for switching the outlet mode, and the operation thereof is performed by a control signal output from the control device 50 via a link mechanism or the like. It is driven by a controlled servo motor (not shown).

  Next, the electric control unit of this embodiment will be described. The control device 50 is composed of a well-known microcomputer including a CPU, ROM, RAM, and its peripheral circuits, and performs various calculations and processing based on a control program stored in the ROM, and is connected to the output side. Controls the operation of various control devices.

  On the input side of the control device 50, there are an inside air sensor that detects the vehicle interior temperature Tr, an outside air sensor that detects the outside air temperature Tam, a solar radiation sensor that detects the amount of solar radiation Ts in the vehicle interior, and the temperature of air blown from the indoor evaporator 20 ( A sensor group 53 for various air conditioning controls such as an evaporator temperature sensor as an evaporator outlet temperature detecting means for detecting an evaporator temperature (Te) and a vehicle speed sensor for detecting a vehicle speed is connected.

  A high pressure refrigerant pressure sensor 54, a first high pressure refrigerant temperature sensor 55, a second high pressure refrigerant temperature sensor 56, and an indoor condenser suction temperature sensor 57 are connected to the input side of the control device 50. The high-pressure refrigerant pressure sensor 54 is high-pressure refrigerant pressure detection means that detects the pressure Ph of the refrigerant that has flowed out of the indoor condenser 12. The first high-pressure refrigerant temperature sensor 55 is high-pressure refrigerant temperature detection means that detects the temperature Th1 of refrigerant that has flowed out of the indoor condenser 12. The second high-pressure refrigerant temperature sensor 56 is high-pressure refrigerant temperature detection means that detects the temperature Th2 of the refrigerant that has flowed out of the indoor condenser 12. The indoor condenser suction temperature sensor 57 is an indoor condenser suction temperature detecting means for detecting the intake air temperature TCIN of the indoor condenser 12.

  An operation panel (not shown) disposed near the instrument panel in the front part of the vehicle interior is connected to the input side of the control device 50, and operation signals are input from various operation switches provided on the operation panel. As various operation switches provided on the operation panel, specifically, an air conditioner switch (A / C switch) for setting whether or not to cool the air blown in the vehicle interior by the indoor air conditioning unit 30, a setting in the vehicle interior A temperature setting switch for setting the temperature is provided.

  The control device 50 is configured such that control means for controlling the operation of various control devices connected to the output side is integrally configured, and the configuration (software and hardware) for controlling the operation of each control device is as follows. Control means for controlling the operation of each control device is configured.

  For example, the configuration for controlling the electric motor of the compressor 11 constitutes the discharge capacity control means, the configuration for controlling the first expansion valve 14 constitutes the first throttle control means, and the configuration for controlling the second expansion valve 19. The structure which comprises a 2nd aperture control means and controls the 1st, 2nd on-off valves 17 and 23 comprises the flow-path switching control means.

  Next, the operation of the vehicle air conditioner 1 of the present embodiment having the above configuration will be described. As described above, the vehicle air conditioner 1 of the present embodiment can be switched to the cooling mode for cooling the passenger compartment, the heating mode for heating the passenger compartment, and the dehumidifying and heating mode for heating while dehumidifying the passenger compartment.

  Switching control processing for each operation mode will be described with reference to FIG. FIG. 4 is a flowchart showing a flow of control processing executed by the control device 50 of the vehicle air conditioner 1 of the present embodiment. The flowchart of FIG. 4 is executed as a subroutine of an air conditioning control main routine (not shown). Each control step in FIG. 4 constitutes various function realizing means of the control device 50.

First, the control device 50 reads the detection signal of the sensor group and the operation signal of the operation panel (S10), and the target blowout that is the target temperature of the blowout air blown into the vehicle interior based on the read detection signal and operation signal values. The temperature TAO is calculated based on the following formula F1 (S20). Accordingly, the control step S20 of the present embodiment constitutes a target blowing temperature determining unit.
TAO = Kset × Tset−Kr × Tr−Kam × Tam−Ks × Ts + C (F1)
Tset is the vehicle interior set temperature set by the temperature setting switch, Tr is the vehicle interior temperature (inside air temperature) detected by the inside air sensor, Tam is the outside air temperature detected by the outside air sensor, and Ts is the solar radiation detected by the solar sensor. Amount. Kset, Kr, Kam, Ks are control gains, and C is a correction constant.

  Based on the target blowing temperature TAO, the control device 50 refers to a control map stored in advance and determines the target blowing temperature TAVO of the indoor condenser 12.

  Next, it is determined whether or not the A / C switch of the operation panel is turned on (S30). As a result, when it is determined that the A / C switch is off (S30: NO), the process proceeds to step S40.

  In step S40, it is determined whether or not the target condenser outlet temperature TAVO is higher than the indoor condenser suction temperature TCIN. As a result, when it is determined that the target condenser outlet temperature TAVO is higher than the indoor condenser suction temperature TCIN (S40: YES), the operation mode is determined to be the heating mode (S50). The heating mode is an operation mode in which the vehicle interior air is heated by the indoor air conditioning unit 30.

  On the other hand, when it is determined that the target condenser outlet temperature TAVO is equal to or lower than the indoor condenser suction temperature TCIN (S40: NO), the operation mode is determined to be the stop (air blowing) mode (S60). The stop (air blowing) mode is an operation mode in which the vehicle interior air is not heated by the indoor air conditioning unit 30.

  In step S70, it is determined whether or not the target condenser outlet temperature TAVO is lower than a predetermined cooling reference temperature α. As a result, when it is determined that the target condenser outlet temperature TAVO is lower than the cooling reference temperature α (S70: YES), the operation mode is determined to be the cooling mode in order to perform cooling of the passenger compartment (S80). ). On the other hand, when it is determined that the target condenser outlet temperature TAVO is equal to or higher than the cooling reference temperature α (S70: NO), the process proceeds to step S90.

  In step S90, it is determined whether or not the target condenser outlet temperature TAVO is lower than a predetermined dehumidifying and heating reference temperature β. The dehumidifying and heating reference temperature β is set higher than the cooling reference temperature α.

  As a result, when it is determined that the target condenser outlet temperature TAVO is lower than the dehumidifying heating reference temperature β (S90: YES), the temperature adjustable range of the outlet air into the passenger compartment is a wide range from the low temperature range to the high temperature range. The first dehumidifying and heating mode, which is the normal dehumidifying and heating mode, is determined (S100).

  On the other hand, when the target condenser outlet temperature TAVO is determined to be equal to or lower than the dehumidifying and heating reference temperature β (S90: NO), the temperature adjustable range of the air blown into the passenger compartment is higher than that in the first dehumidifying and heating mode. Is determined to be the second dehumidifying and heating mode (S110).

  In this way, each operation mode is appropriately switched between the heating mode, the stop (air blowing) mode, the cooling mode, the first dehumidifying heating mode, and the second dehumidifying heating mode according to the operating environment of the vehicle air conditioner 1. be able to.

  Next, operations in the heating mode, stop (air blowing) mode, cooling mode, first dehumidifying heating mode, and second dehumidifying heating mode will be described.

(A) Heating Mode In the heating mode, the control device 50 opens the second refrigerant passage 16 with the first opening / closing valve 17 and closes (closes) the bypass passage 22 with the second opening / closing valve 23. Further, the third refrigerant passage 18 is closed by the second expansion valve 19 (fully closed). Thereby, in the refrigerating cycle apparatus 10, as shown by the black arrow of FIG. 1, it switches to the refrigerant | coolant flow path through which a refrigerant | coolant flows.

  With this refrigerant flow path configuration, the control device 50 operates the various control devices connected to the control device 50 based on the target blowout temperature TAO, the target condenser blowout temperature TAVO, the detection signal of the sensor group, etc. Control signal to be output to the control device).

  For example, the refrigerant discharge capacity of the compressor 11, that is, the control signal output to the electric motor 11b of the compressor 11 is determined as follows. First, based on the deviation between the target condenser blowout temperature TAVO and the indoor condenser blowout temperature TAV, the indoor condenser blowout temperature TAV blown into the vehicle interior approaches the target condenser blowout temperature TAVO using a feedback control method. Thus, the control signal output to the electric motor 11b of the compressor 11 is determined.

  The indoor condenser outlet temperature TAV is calculated based on the detection value Ph of the high-pressure refrigerant pressure sensor 54 and the like.

  The compressor 11 cannot be driven at a rotational speed lower than a predetermined lower limit rotational speed because of the drive torque. When it is desired to drive the compressor 11 at a rotation speed lower than the lower limit rotation speed, an operation corresponding to a rotation speed lower than the lower limit rotation speed is obtained by performing intermittent operation in which the compressor 11 is driven and stopped repeatedly.

  The control signal output to the first expansion valve 14 is determined so that the degree of supercooling of the refrigerant flowing into the first expansion valve 14 approaches the target degree of supercooling. The target degree of supercooling is determined so that the coefficient of performance (COP) of the cycle approaches the maximum value.

  Specifically, an instruction opening degree EVHn (hereinafter referred to as an expansion valve instruction opening degree) of the first expansion valve 14 is determined by executing the control process shown in the flowchart of FIG.

First, in step S510, a deviation Sn between the target supercooling degree SCO of the outlet side refrigerant of the indoor condenser 12 and the estimated value SC of the subcooling degree of the outlet side refrigerant of the indoor condenser 12 is calculated based on the following formula F2. .
Sn = SCO-SC (F2)
The target supercooling degree SCO of the refrigerant on the outlet side of the indoor condenser 12 is stored in advance in the control device 50 based on values such as the outside air temperature Tam, the intake air temperature TIN of the indoor condenser 12 and the target outlet temperature TAO. Calculated with reference to the control map.

  The intake air temperature of the indoor condenser 12 is substantially the same as the blown air temperature (evaporator temperature) Te from the indoor evaporator 20.

The estimated value SC of the degree of supercooling of the refrigerant on the outlet side of the indoor condenser 12 is calculated and estimated using the following formula F3 based on the pressure Ph and the temperature Th1 of the refrigerant flowing out of the indoor condenser 12.
SC = Ths-Th1 (F3)
Ths is a refrigerant saturation temperature corresponding to the pressure Ph (high pressure of the refrigeration cycle) of the refrigerant flowing out from the indoor condenser 12.

  In subsequent step S520, the operation amount ΔEVH of the first expansion valve 14 is calculated with reference to the control map stored in advance in the control device 50 based on the deviation Sn calculated in step S510. Specifically, the operation amount ΔEVH of the first expansion valve 14 is calculated so that the value of the deviation Sn approaches 0.

In the subsequent step S530, a temporary expansion valve instruction opening EVHn_t is calculated based on the following formula F4. The temporary expansion valve instruction opening EVHn_t is a temporary value of the expansion valve instruction opening EVHn.
EVHn_t = EVHn−1 + ΔEVH (F4)
EVHn-1 is the previous expansion valve instruction opening.

  In subsequent step S540, it is determined whether or not the compressor 11 is intermittently operated. If it is determined that the compressor 11 is not intermittently operated and is operating normally (S540: NO), the process proceeds to step S550. On the other hand, when it determines with the compressor 11 being intermittently operated (S540: YES), it progresses to step S560.

  In step S550, the temporary expansion valve instruction opening EVHn_t calculated in step S530 is determined as the expansion valve instruction opening EVHn. Thereby, since the supercooling degree of the refrigerant flowing into the first expansion valve 14 approaches the target supercooling degree, the coefficient of performance (COP) of the cycle approaches the maximum value.

On the other hand, in step S560, a lower limit EVHmin of the expansion valve instruction opening is calculated based on the following formula F5.
EVHmin = EVHmin_BLW + EVHmin_TIN + EVHmin_Ph (F5)
EVHmin_BLW is calculated with reference to a control map (FIG. 6A) stored in advance in the control device 50 based on the blower output BLW (the output of the blower 32). As the blower output BLW is larger and the amount of air blown to the indoor evaporator 20 is larger, the refrigerant becomes easier to condense in the indoor evaporator 20, so the value of EVHmin_BLW is increased.

  EVHmin_TIN is calculated based on the value of the intake air temperature TIN of the indoor condenser 12 with reference to a control map (FIG. 6B) stored in the control device 50 in advance. As the intake air temperature TIN of the indoor condenser 12 is lower, the refrigerant is more easily condensed in the indoor evaporator 20, and thus the value of EVHmin_TIN is increased.

  EVHmin_Ph is calculated with reference to a control map (FIG. 6C) stored in advance in the control device 50 based on the value of the pressure Ph of the refrigerant flowing out from the indoor condenser 12. The higher the pressure Ph of the refrigerant flowing out of the indoor condenser 12, the easier it is for the refrigerant to condense in the indoor evaporator 20, so the value of EVHmin_Ph is increased.

In the following step S570, the expansion valve instruction opening EVHn is calculated based on the following formula F6.
EVHn = MAX [EVHn_t, EVHmin] (F6)
MAX [EVHn_t, EVHmin] in Formula F6 means a larger value of the temporary expansion valve instruction opening EVHn_t and the lower limit EVHmin of the expansion valve instruction opening.

  Thereby, when the compressor 11 is intermittently operated, the opening degree of the first expansion valve 14 becomes equal to or higher than the lower limit value EVHmin, so that the opening degree of the first expansion valve 14 can be suppressed from being excessively reduced. Therefore, it is possible to suppress the liquid refrigerant from staying in the indoor condenser 12, so that it is possible to suppress the temperature distribution and temperature drop of the air blown from the indoor condenser 12, and thus improve the passenger comfort.

  Regarding the control signal output to the servo motor of the air mix door 36, the air mix door 36 closes the cold air bypass passage 35, and the total flow rate of the blown air after passing through the indoor evaporator 20 is the heater core 34 and the indoor condenser 12. To pass through the air passage.

  Then, the control signal determined as described above is output to various control devices. Thereafter, until the operation stop of the vehicle air conditioner 1 is requested by the operation panel, a control routine such as operation mode determination processing → determination of operation states of various control devices → output of control signals and the like is repeated at predetermined intervals. . Such a control routine is repeated in the other operation modes.

  Therefore, in the refrigeration cycle apparatus 10 in the heating mode, the high-pressure refrigerant discharged from the compressor 11 flows into the indoor condenser 12. The refrigerant that has flowed into the indoor condenser 12 exchanges heat with the vehicle interior blown air that has been blown from the blower 32 and passed through the indoor evaporator 20 to dissipate heat. Thereby, vehicle interior blowing air is heated.

  The refrigerant flowing out of the indoor condenser 12 flows into the first expansion valve 14 through the first refrigerant passage 13 and is decompressed and expanded at the first expansion valve 14 until it becomes a low-pressure refrigerant. The low-pressure refrigerant decompressed by the first expansion valve 14 flows into the outdoor heat exchanger 15 and absorbs heat from the outside air blown from the blower fan. The refrigerant that has flowed out of the outdoor heat exchanger 15 flows into the accumulator 21 through the second refrigerant passage 16 and is separated into gas and liquid.

  The gas-phase refrigerant separated by the accumulator 21 is sucked from the suction side of the compressor 11 and is compressed again by the compressor 11. The liquid-phase refrigerant separated by the accumulator 21 is stored in the accumulator 21 as surplus refrigerant that is not necessary for exhibiting the refrigerating capacity required for the cycle. Since the third refrigerant passage 18 is closed by the second expansion valve 19, no refrigerant flows into the indoor evaporator 20.

  As described above, in the heating mode, the heat of the high-pressure refrigerant discharged from the compressor 11 by the indoor condenser 12 is radiated to the vehicle interior blown air, and the heat of the cooling water is heated by the heater core 34 in the vehicle interior blown air. The heated vehicle interior blown air can be blown out into the vehicle interior. Thereby, heating of a vehicle interior is realizable.

(B) Cooling Mode In the cooling mode, the control device 50 closes the second refrigerant passage 16 with the first opening / closing valve 17 and closes the bypass passage 22 with the second opening / closing valve 23. Further, the first refrigerant passage 13 is fully opened by the first expansion valve 14. Thereby, in the refrigerating cycle apparatus 10, it switches to the 1st refrigerant | coolant flow path through which a refrigerant | coolant flows as shown by the white arrow of FIG.

  With this refrigerant flow path configuration, the control device 50 operates various control devices connected to the control device 50 based on the target blowing temperature TAO, the detection signal of the sensor group, etc. (control signals output to the various control devices) ).

  For example, the refrigerant discharge capacity of the compressor 11, that is, the control signal output to the electric motor 11b of the compressor 11 is determined as follows. First, based on the target blowing temperature TAO, a target evaporator blowing temperature TEO of the blown air blown out from the indoor evaporator 20 is determined with reference to a control map stored in the control device 50 in advance. Accordingly, in the control routine executed by the control device 50, the control step for determining the target evaporator outlet temperature TEO constitutes the target evaporator outlet temperature determining means.

  Then, based on the deviation between the target evaporator blowout temperature TEO and the detected value of the evaporator temperature sensor, the temperature of the air that has passed through the indoor evaporator 20 using the feedback control method approaches the target blowout temperature TAO. A control signal output to the electric motor 11b of the compressor 11 is determined.

  The control signal output to the second expansion valve 19 is determined such that the degree of supercooling of the refrigerant flowing into the second expansion valve 19 approaches a predetermined target degree of subcooling so that the COP approaches the maximum value. Is done.

  Regarding the control signal output to the servo motor of the air mix door 36, the air mix door 36 closes the air passage of the heater core 34 and the indoor condenser 12, and the total flow rate of the blown air after passing through the indoor evaporator 20 is cold air. It is determined to pass through the bypass passage 35.

  Therefore, in the refrigeration cycle apparatus 10 in the cooling mode, the high-pressure refrigerant discharged from the compressor 11 flows into the indoor condenser 12. At this time, since the air mix door 36 closes the air passages of the heater core 34 and the indoor condenser 12, the refrigerant that has flowed into the indoor condenser 12 hardly exchanges heat with the air blown into the vehicle interior, and thus the indoor condenser. 12 flows out.

  The refrigerant that has flowed out of the indoor condenser 12 flows into the first expansion valve 14 through the first refrigerant passage 13. At this time, since the first expansion valve 14 fully opens the first refrigerant passage 13, the refrigerant flowing out of the indoor condenser 12 is not decompressed by the first expansion valve 14, and is transferred to the outdoor heat exchanger 15. Inflow. The refrigerant flowing into the outdoor heat exchanger 15 radiates heat to the outside air blown from the blower fan in the outdoor heat exchanger 15.

  The refrigerant flowing out of the outdoor heat exchanger 15 flows into the second expansion valve 19 via the third refrigerant passage 18 and is decompressed and expanded at the second expansion valve 19 until it becomes a low-pressure refrigerant. The low-pressure refrigerant depressurized by the second expansion valve 19 flows into the indoor evaporator 20, absorbs heat from the vehicle interior air blown from the blower 32, and evaporates. Thereby, vehicle interior blowing air is cooled.

  The refrigerant flowing out of the indoor evaporator 20 flows into the accumulator 21 and is separated into gas and liquid. The gas-phase refrigerant separated by the accumulator 21 is sucked from the suction side of the compressor 11 and is compressed again by the compressor 11. The liquid-phase refrigerant separated by the accumulator 21 is stored in the accumulator 21 as surplus refrigerant that is not necessary for exhibiting the refrigerating capacity required for the cycle.

  As described above, in the cooling mode, since the air passages of the indoor condenser 12 and the heater core 34 are closed by the air mix door 36, the air blown into the vehicle interior is blown out into the vehicle interior. Can do. Thereby, cooling of a vehicle interior is realizable.

(C) First Dehumidifying Heating Mode In the first dehumidifying heating mode, the control device 50 closes the second refrigerant passage 16 with the first on-off valve 17 and closes the bypass passage 22 with the second on-off valve 23. Then, the first and second expansion valves 14 and 19 are set to the throttle state or the fully open state. Thereby, the refrigerating cycle apparatus 10 is switched to the 1st refrigerant | coolant flow path through which a refrigerant | coolant flows as shown by the white horizontal line arrow of FIG. 1 similarly to the air_conditioning | cooling mode. In the first dehumidifying and heating mode (first refrigerant flow path), the outdoor heat exchanger 15 and the indoor evaporator 20 are connected in series with respect to the refrigerant flow.

  With this refrigerant flow path configuration, the control device 50 operates the various control devices connected to the control device 50 based on the target blowout temperature TAO, the target condenser blowout temperature TAVO, the detection signal of the sensor group, etc. Control signal to be output to the control device).

  For example, the control signal output to the electric motor 11b of the compressor 11 is determined similarly to the cooling mode. Regarding the control signal output to the servo motor of the air mix door 36, the air mix door 36 closes the cold air bypass passage 35, and the total flow rate of the blown air after passing through the indoor evaporator 20 is the heater core 34 and the indoor condenser 12. To pass through the air passage.

  About the 1st expansion valve 14 and the 2nd expansion valve 19, it has changed according to target condenser blowing temperature TAVO. Specifically, the control device 50 reduces the passage area of the first refrigerant passage 13 by the first expansion valve 14 and increases the second expansion valve 19 by the first expansion valve 19 as the target condenser outlet temperature TAVO increases. 3 The passage area of the refrigerant passage 18 is increased. Thereby, in the 1st dehumidification heating mode, the mode of four steps from the 1st mode to the 4th mode is performed.

(C-1) First mode The first mode is executed when the target condenser outlet temperature TAVO is equal to or higher than the cooling reference temperature α and equal to or lower than a predetermined first reference temperature in the first dehumidifying heating mode. The

  In the first mode, the first expansion passage 14 makes the first refrigerant passage 13 fully open, and the second expansion valve 19 is in the throttle state. Therefore, the cycle configuration (refrigerant flow path) is exactly the same refrigerant flow path as in the cooling mode, but the air mix door 36 fully opens the air passage on the indoor condenser 12 and heater core 34 side, so the cycle is circulated. The state of the refrigerant to be changed changes as shown in the Mollier diagram of FIG.

  That is, as shown in FIG. 7, the high-pressure refrigerant (point a1) discharged from the compressor 11 flows into the indoor condenser 12 and is cooled by the indoor evaporator 20 and dehumidified in the vehicle interior. Heat exchange is performed to dissipate heat (point a1 → point a2 in FIG. 7). Thereby, vehicle interior blowing air is heated.

  The refrigerant that has flowed out of the indoor condenser 12 flows into the first expansion valve 14 through the first refrigerant passage 13. At this time, since the first expansion valve 14 fully opens the first refrigerant passage 13, the refrigerant flowing out of the indoor condenser 12 is not decompressed by the first expansion valve 14, and is transferred to the outdoor heat exchanger 15. Inflow. And the refrigerant | coolant which flowed into the outdoor heat exchanger 15 is thermally radiated to the external air ventilated from the ventilation fan in the outdoor heat exchanger 15 (a2 point-> a3 point of FIG. 7).

  The refrigerant that has flowed out of the outdoor heat exchanger 15 flows into the second expansion valve 19 through the third refrigerant passage 18 and is decompressed and expanded until it becomes a low-pressure refrigerant in the second expansion valve 19 (FIG. 7). a3 point → a4 point). The low-pressure refrigerant decompressed by the second expansion valve 19 flows into the indoor evaporator 20, absorbs heat from the air blown from the vehicle interior blown from the blower 32, and evaporates (point a4 → a5 in FIG. 7). Thereby, vehicle interior blowing air is cooled. Then, the refrigerant that has flowed out of the indoor evaporator 20 flows from the accumulator 21 to the suction side of the compressor 11 and is compressed again by the compressor 11 as in the cooling mode.

  As described above, in the first mode of the first dehumidifying and heating mode, the vehicle interior blown air cooled and dehumidified by the indoor evaporator 20 can be heated by the indoor condenser 12 and blown out into the vehicle interior. Thereby, dehumidification heating of a vehicle interior is realizable.

(C-2) Second Mode The second mode is executed when the target condenser outlet temperature TAVO is higher than the first reference temperature and equal to or lower than a predetermined second reference temperature. In the second mode, the first expansion valve 14 is set in the throttle state, and the throttle opening degree (passage area of the third refrigerant passage 18) of the second expansion valve 19 is set higher than that in the first mode. Therefore, in the second mode, the state of the refrigerant circulating in the cycle changes as shown in the Mollier diagram of FIG.

  That is, as shown in FIG. 8, the high-pressure refrigerant (point b1) discharged from the compressor 11 flows into the indoor condenser 12 and is cooled by the indoor evaporator 20 and dehumidified in the vehicle interior. The heat is exchanged to dissipate heat (b1 point → b2 point in FIG. 8). Thereby, vehicle interior blowing air is heated.

  The refrigerant flowing out of the indoor condenser 12 flows into the first expansion valve 14 via the first refrigerant passage 13 and is depressurized until it becomes an intermediate pressure refrigerant (b2 point → b3 point in FIG. 8). Then, the intermediate-pressure refrigerant decompressed by the first expansion valve 14 flows into the outdoor heat exchanger 15 and radiates heat to the outside air blown from the blower fan (b3 point → b4 point in FIG. 8).

  The refrigerant that has flowed out of the outdoor heat exchanger 15 flows into the second expansion valve 19 via the third refrigerant passage 18 and is decompressed and expanded until it becomes a low-pressure refrigerant in the second expansion valve 19 (FIG. 8). b4 point → b5 point). The low-pressure refrigerant decompressed by the second expansion valve 19 flows into the indoor evaporator 20, and absorbs heat from the vehicle interior air blown from the blower 32 to evaporate (b5 point → b6 point in FIG. 8). Thereby, vehicle interior blowing air is cooled. Then, the refrigerant that has flowed out of the indoor evaporator 20 flows from the accumulator 21 to the suction side of the compressor 11 and is compressed again by the compressor 11 as in the cooling mode.

  As described above, during the second mode of the first dehumidifying and heating mode, the vehicle interior blown air cooled and dehumidified by the indoor evaporator 20 is heated by the indoor condenser 12 in the same manner as in the first mode. Can be blown out. Thereby, dehumidification heating of a vehicle interior is realizable.

  At this time, in the second mode, since the first expansion valve 14 is in the throttle state, the temperature of the refrigerant flowing into the outdoor heat exchanger 15 can be lowered compared to the first mode. Therefore, the temperature difference between the refrigerant temperature and the outside air temperature in the outdoor heat exchanger 15 can be reduced, and the heat radiation amount of the refrigerant in the outdoor heat exchanger 15 can be reduced.

  As a result, the amount of heat released from the refrigerant in the indoor condenser 12 can be increased without increasing the refrigerant circulation flow rate that circulates the cycle in the first mode, and the refrigerant is blown out from the indoor condenser 12 than in the first mode. The temperature of the blown air can be increased.

(C-3) Third Mode The third mode is executed when the target condenser outlet temperature TAVO is higher than the second reference temperature and equal to or lower than a predetermined third reference temperature. In the third mode, the throttle opening of the first expansion valve 14 (passage area of the first refrigerant passage 13) is set to a throttle state that is smaller than that in the second mode, and the throttle opening of the second expansion valve 19 (third The throttle area is set such that the passage area of the refrigerant passage 18 is larger than that in the second mode. Therefore, in the third mode, the state of the refrigerant circulating in the cycle changes as shown in the Mollier diagram of FIG.

  That is, as shown in FIG. 9, the high-pressure refrigerant (point c1) discharged from the compressor 11 flows into the indoor condenser 12 and is cooled by the indoor evaporator 20 and dehumidified in the vehicle interior. Heat exchange is performed to dissipate heat (point c1 → c2 in FIG. 9). Thereby, vehicle interior blowing air is heated.

  The refrigerant flowing out of the indoor condenser 12 flows into the first expansion valve 14 through the first refrigerant passage 13 and is depressurized until it becomes an intermediate pressure refrigerant having a temperature lower than the outside air temperature (point c2 in FIG. 9 → c3 points). The intermediate-pressure refrigerant decompressed by the first expansion valve 14 flows into the outdoor heat exchanger 15 and absorbs heat from the outside air blown from the blower fan (point c3 → point c4 in FIG. 9).

  The refrigerant flowing out of the outdoor heat exchanger 15 flows into the second expansion valve 19 via the third refrigerant passage 18 and is decompressed and expanded until it becomes a low-pressure refrigerant in the second expansion valve 19 (FIG. 9). c4 point → c5 point). The low-pressure refrigerant decompressed by the second expansion valve 19 flows into the indoor evaporator 20 and absorbs heat from the vehicle interior air blown from the blower 32 to evaporate (point c5 → c6 in FIG. 9). Thereby, vehicle interior blowing air is cooled. Then, the refrigerant that has flowed out of the indoor evaporator 20 flows from the accumulator 21 to the suction side of the compressor 11 and is compressed again by the compressor 11 as in the cooling mode.

  As described above, during the third mode of the first dehumidifying and heating mode, the vehicle interior blown air cooled by the indoor evaporator 20 and dehumidified is heated by the indoor condenser 12 in the same manner as in the first and second modes. Can be blown into the passenger compartment. Thereby, dehumidification heating of a vehicle interior is realizable.

  At this time, in the third mode, the outdoor heat exchanger 15 is caused to function as a heat absorber (evaporator) by reducing the throttle opening of the first expansion valve 14, so that the indoor condenser is more than in the second mode. The temperature blown from 12 can be raised.

  As a result, with respect to the second mode, the suction refrigerant density of the compressor 11 can be increased, and the heat release amount of the refrigerant in the indoor condenser 12 without increasing the rotation speed (refrigerant discharge capacity) of the compressor 11. Can be increased, and the temperature of the blown-out air blown out from the indoor condenser 12 can be increased more than in the second mode.

(C-4) Fourth Mode The fourth mode is executed when the target condenser outlet temperature TAVO is higher than the third reference temperature. In the fourth mode, the throttle opening state (passage area of the first refrigerant passage 13) of the first expansion valve 14 is made smaller than that in the third mode, and the third refrigerant passage 18 is set by the second expansion valve 19. Is fully open. Therefore, in the fourth mode, the state of the refrigerant circulating in the cycle changes as shown in the Mollier diagram of FIG.

  That is, as shown in FIG. 10, the high-pressure refrigerant (point d1) discharged from the compressor 11 flows into the indoor condenser 12 and is cooled by the indoor evaporator 20 and dehumidified in the vehicle interior. Heat is exchanged to dissipate heat (point d1 → point d2 in FIG. 10). Thereby, vehicle interior blowing air is heated.

  The refrigerant that has flowed out of the indoor condenser 12 flows into the first expansion valve 14 via the first refrigerant passage 13 and is depressurized until it becomes a low-pressure refrigerant (point d2 → point d3 in FIG. 10). And the low-pressure refrigerant decompressed by the first expansion valve 14 flows into the outdoor heat exchanger 15 and absorbs heat from the outside air blown from the blower fan (point d3 → point d4 in FIG. 10).

  The refrigerant that has flowed out of the outdoor heat exchanger 15 flows into the second expansion valve 19 through the third refrigerant passage 18. At this time, since the second expansion valve 19 fully opens the third refrigerant passage 18, the refrigerant that has flowed out of the outdoor heat exchanger 15 is not decompressed by the second expansion valve 19 and is sent to the indoor evaporator 20. Inflow.

  The low-pressure refrigerant that has flowed into the indoor evaporator 20 absorbs heat from the air blown from the vehicle interior blown from the blower 32 and evaporates (point d4 → d5 in FIG. 10). Thereby, vehicle interior blowing air is cooled. Then, the refrigerant that has flowed out of the indoor evaporator 20 flows from the accumulator 21 to the suction side of the compressor 11 and is compressed again by the compressor 11 as in the cooling mode.

  As described above, in the fourth mode of the first dehumidifying and heating mode, the vehicle interior blown air cooled and dehumidified by the indoor evaporator 20 is heated by the indoor condenser 12 as in the first to third modes. Can be blown into the passenger compartment. Thereby, dehumidification heating of a vehicle interior is realizable.

  At this time, in the fourth mode, as in the third mode, the outdoor heat exchanger 15 can function as a heat absorber (evaporator), and the throttle opening degree of the first expansion valve 14 can be made larger than that in the third mode. Since it is reduced, the refrigerant evaporation temperature in the outdoor heat exchanger 15 can be lowered. Therefore, the temperature difference between the refrigerant temperature and the outside air temperature in the outdoor heat exchanger 15 can be increased more than in the third mode, and the heat absorption amount of the refrigerant in the outdoor heat exchanger 15 can be increased.

  As a result, with respect to the third mode, the suction refrigerant density of the compressor 11 can be increased, and the heat release amount of the refrigerant in the indoor condenser 12 without increasing the rotation speed (refrigerant discharge capacity) of the compressor 11. And the temperature of the air blown out from the indoor condenser 12 can be increased more than in the third mode.

  Thus, in 1st dehumidification heating mode, by changing the throttle opening of the 1st expansion valve 14 and the 2nd expansion valve 19 according to target condenser blowing temperature TAVO computed based on target blowing temperature TAO, The temperature of the blown-out air blown into the passenger compartment can be adjusted over a wide range from the low temperature range to the high temperature range.

  In other words, in the first dehumidifying and heating mode, while switching the outdoor heat exchanger 15 from a state where it functions as a radiator that radiates the refrigerant to a state where it functions as an evaporator that absorbs heat from the refrigerant, the refrigerant in the outdoor heat exchanger 15 is changed. The amount of heat release or the amount of heat absorption can be adjusted.

  Therefore, the amount of heat released from the refrigerant in the indoor condenser 12 can be adjusted in a wider range than the cycle configuration in which the outdoor heat exchanger 15 functions as either a radiator or an evaporator, and the air-conditioning target space can be adjusted during the dehumidifying operation. The temperature adjustment range of the blown air blown out to can be expanded.

(D) Second Dehumidification Heating Mode In the second dehumidification heating mode, the control device 50 opens the second refrigerant passage 16 at the first on-off valve 17 and opens the bypass passage 22 at the second on-off valve 23. Then, each of the first and second expansion valves 14 and 19 is set to the throttle state. Accordingly, the refrigeration cycle apparatus 10 is switched to the second refrigerant flow path through which the refrigerant flows, as indicated by the white oblique arrows in FIG. In the second dehumidifying and heating mode (second refrigerant flow path), the outdoor heat exchanger 15 and the indoor evaporator 20 are connected in parallel to the refrigerant flow.

  With this refrigerant flow path configuration, the control device 50 operates various control devices connected to the control device 50 based on the target blowing temperature TAO, the detection signal of the sensor group, etc. (control signals output to the various control devices) ).

  For example, the control signal output to the electric motor 11b of the compressor 11 is determined in the same manner as in the heating mode. Regarding the control signal output to the servo motor of the air mix door 36, the air mix door 36 closes the cold air bypass passage 35, and the total flow rate of the blown air after passing through the indoor evaporator 20 is the heater core 34 and the indoor condenser 12. To pass through the air passage.

  About the control signal output to the 1st expansion valve 14 and the 2nd expansion valve 19, it determines so that it may become the predetermined opening for 2nd dehumidification heating modes defined beforehand.

  Therefore, in the refrigeration cycle apparatus 10 in the second dehumidifying and heating mode, as shown in the Mollier diagram of FIG. 11, the high-pressure refrigerant (point e1) discharged from the compressor 11 flows into the indoor condenser 12, Heat is dissipated by exchanging heat with the air blown into the passenger compartment after being cooled and dehumidified by the indoor evaporator 20 (point e1 → point e2 in FIG. 11). Thereby, vehicle interior blowing air is heated.

  The refrigerant flowing out of the indoor condenser 12 flows into the first expansion valve 14 via the first refrigerant passage 13 and flows into the second expansion valve 19 via the bypass passage 22. The high-pressure refrigerant that has flowed into the first expansion valve 14 is depressurized until it becomes a low-pressure refrigerant (point e2 → point e3 in FIG. 11). And the low-pressure refrigerant decompressed by the first expansion valve 14 flows into the outdoor heat exchanger 15 and absorbs heat from the outside air blown from the blower fan (point e3 → point e5 in FIG. 11).

  On the other hand, the high-pressure refrigerant flowing into the second expansion valve 19 is depressurized until it becomes a low-pressure refrigerant (point e2 → point e4 in FIG. 11). The low-pressure refrigerant decompressed by the second expansion valve 19 flows into the indoor evaporator 20, absorbs heat from the air blown from the vehicle interior blown from the blower 32, and evaporates (point e4 → point e6 in FIG. 11). ). Thereby, vehicle interior blowing air is cooled.

  The refrigerant flowing out of the outdoor heat exchanger 15 and the refrigerant flowing out of the indoor evaporator 20 flow from the accumulator 21 to the suction side of the compressor 11 and are compressed again by the compressor 11. In the present embodiment, the pressure of the low-pressure refrigerant flowing out of the outdoor heat exchanger 15 and the pressure of the low-pressure refrigerant flowing out of the indoor evaporator 20 are equivalent. Since the check valve 24 is provided in the third refrigerant passage 18, the refrigerant does not flow backward from the bypass passage 22 to the outlet side of the outdoor heat exchanger 15.

As described above, in the second dehumidifying and heating mode, unlike the first dehumidifying and heating mode, the refrigerant flow becomes a refrigerant flow path in which the outdoor heat exchanger 15 and the indoor evaporator 20 are connected in parallel to the refrigerant flow. In the dehumidifying heating mode, the pressure of the refrigerant in the indoor evaporator 20 can be made equal to or higher than the pressure of the refrigerant in the outdoor heat exchanger 15. In other words, the heat absorption capacity in the outdoor heat exchanger 15 can be increased as compared with the first dehumidifying and heating mode. Therefore, the temperature of the blown air dehumidified by the indoor evaporator 20 can be adjusted by the indoor condenser 12 in a higher temperature range than in the first dehumidifying and heating mode.
(E) Stop (Blower) Mode In the stop (blower) mode, the control device 50 stops the compressor 11. Regarding the control signal output to the servo motor of the air mix door 36, the air mix door 36 closes the air passage of the heater core 34 and the indoor condenser 12, and the total flow rate of the blown air after passing through the indoor evaporator 20. Is determined to pass through the cold air bypass passage 35.

  Accordingly, in the refrigeration cycle apparatus 10 in the stop (air blowing) mode, the refrigerant does not circulate, so that the air blown from the vehicle interior is not exchanged by the indoor condenser 12 and the indoor evaporator 20, and the temperature remains unchanged. Is blown into the passenger compartment. Thereby, the ventilation to a vehicle interior is realizable.

  In the vehicle air conditioner 1 of the present embodiment described above, as described above, by switching the refrigerant flow path of the refrigeration cycle apparatus 10, by performing appropriate cooling, heating, and dehumidifying heating in the vehicle interior, Comfortable air conditioning in the room can be realized.

  In the present embodiment, as described in step S50, when the control device 50 performs intermittent operation control that repeats driving and stopping of the compressor 11, continuous operation control that continuously drives the compressor 11 is performed. The operation of the valve body 14b of the first expansion valve 14 is controlled so that the lower limit value of the cross-sectional area of the expansion valve passage 14a of the first expansion valve 14 is increased as compared with the case where the operation is performed (steps S540 to S570).

  According to this, when the compressor 11 is operated intermittently, the first expansion valve 14 makes the cross-sectional area of the expansion valve passage 14a too small compared with the case where the compressor 11 is operated continuously, and the refrigerant flow is increased. It can suppress that it is narrowed down too much. Therefore, it is possible to suppress the liquid refrigerant from staying in the indoor condenser 12.

  In the present embodiment, as described in step S50, the control device 50 calculates the instruction opening degree EVHn_t of the first expansion valve 14 based on the degree of supercooling of the refrigerant that has flowed out of the indoor condenser 12. And the control apparatus 50 calculates the lower limit value EVHmin of the instruction | indication opening degree of the 1st expansion valve 14, irrespective of the supercooling degree of the refrigerant | coolant which flowed out from the indoor condenser 12, when performing intermittent operation control ( Steps S510 to S530, S560).

  According to this, when the intermittent operation control of the compressor 11 is performed, the first expansion valve 14 is basically controlled while controlling the operation of the first expansion valve 14 based on the degree of supercooling of the refrigerant flowing out from the indoor condenser 12. The expansion of the refrigerant flow with the expansion valve 14 can be suppressed.

  In the present embodiment, as described in step S50, when the control device 50 performs intermittent operation control of the compressor 11, the amount of air blown from the blower 32, the temperature TIN of the air sucked into the indoor condenser 12, and the room A lower limit value EVHmin of the indicated opening degree of the first expansion valve 14 is determined based on at least one of the refrigerant pressure Ph flowing into the condenser 12 (step S560).

  According to this, when the intermittent operation control of the compressor 11 is performed, the lower limit value EVHmin of the indicated opening degree of the first expansion valve 14 can be determined according to the conspicuousness of the refrigerant condensation in the indoor condenser 12.

  In the present embodiment, as described in step S50, the control device 50 switches between continuous operation control and intermittent operation control of the compressor 11 in the heating mode.

  According to this, even if the intermittent operation control of the compressor 11 is performed in the heating mode, the liquid refrigerant can be prevented from staying in the indoor condenser 12, so that the temperature distribution and temperature drop of the air blown from the indoor condenser 12 can be suppressed. As a result, passenger comfort can be improved.

(Second Embodiment)
In the first embodiment, when the compressor 11 is intermittently operated, the expansion valve instruction opening EVHn is set to the larger value of the temporary expansion valve instruction opening EVHn_t and the lower limit EVHmin of the expansion valve instruction opening. However, in the present embodiment, as shown in FIG. 12, when the compressor 11 is intermittently operated, the expansion valve instruction opening EVHn is set to the blower regardless of the temporary expansion valve instruction opening EVHn_t. It is determined based on the output BLW, the intake air temperature TIN of the indoor condenser 12, and the pressure Ph of the refrigerant flowing out of the indoor condenser 12.

Specifically, when it is determined in step S540 that the compressor 11 is intermittently operated (S540: YES), the process proceeds to step S561, and the expansion valve instruction opening EVHON-OFF during the intermittent operation is expressed by the following formula. Calculate based on F7.
EVHON-OFF = EVHON-OFF_BLW + EVHON-OFF_TIN + EVHON-OFF_Ph (F7)
EVHON-OFF_BLW is calculated based on the blower output BLW (the output of the blower 32) with reference to a control map (FIG. 13A) stored in advance in the control device 50. As the value of the blower output BLW (output of the blower 32) is larger and the amount of air blown to the indoor evaporator 20 is larger, the refrigerant is more easily condensed in the indoor evaporator 20, so the value of EVHON-OFF_BLW is increased.

  EVHON-OFF_TIN is the suction of the indoor condenser 12 calculated with reference to the control map (FIG. 13B) stored in advance in the control device 50 based on the value of the intake air temperature TIN of the indoor condenser 12. The lower the air temperature TIN, the easier it is for the refrigerant to condense in the indoor evaporator 20, so the value of EVHON-OFF_TIN is increased.

  EVHON-OFF_Ph is calculated with reference to a control map (FIG. 13C) stored in advance in the control device 50 based on the value of the pressure Ph of the refrigerant flowing out from the indoor condenser 12. The higher the pressure Ph of the refrigerant flowing out of the indoor condenser 12, the easier it is for the refrigerant to condense in the indoor evaporator 20, so the EVHON-OFF_Ph value is increased.

  The minimum EVHON-OFF value is larger than the minimum value of the temporary expansion valve instruction opening EVHn_t.

  In the subsequent step S571, the expansion valve instruction opening EVHn is determined to be the same value as the expansion valve instruction opening EVHON-OFF during the intermittent operation calculated in step S561 (EVHn = EVHON-OFF).

  Thereby, similarly to the said 1st Embodiment, when the compressor 11 is intermittently operated, it can suppress that the opening degree of the 1st expansion valve 14 is restrict | squeezed too much.

  In the present embodiment, as described in step S50, when the control device 50 performs the continuous operation control of the compressor 11, the control valve 50 sets the indicated opening degree EVHn_t of the expansion valve 14 of the refrigerant flowing out from the indoor condenser 12. Calculated based on the degree of supercooling. When the control device 50 performs the intermittent operation control of the compressor 11, the instruction opening degree EVHON-OFF of the first expansion valve 14 is independent of the degree of supercooling of the refrigerant that has flowed out of the indoor condenser 12. Calculate (steps S510 to S530, S561).

  According to this, when the intermittent operation control of the compressor 11 is performed, it is possible to reliably suppress the refrigerant flow from being excessively throttled by the first expansion valve 14.

  In the present embodiment, as described in step S50, when the control device 50 performs the intermittent operation control of the compressor 11, the control opening 50 sets the indicated opening degree EVHON-OFF of the first expansion valve 14 to the blower amount of the blower 32. This is determined based on at least one of the temperature TIN of the air sucked into the indoor condenser 12 and the pressure Ph of the refrigerant flowing into the indoor condenser 12 (step S561).

  According to this, when the intermittent operation control of the compressor 11 is performed, the lower limit value EVHmin of the indicated opening degree of the first expansion valve 14 can be determined according to the conspicuousness of the refrigerant condensation in the indoor condenser 12.

(Third embodiment)
In the above embodiment, when it is determined that the compressor 11 is intermittently operated, the first expansion valve 14 is throttled by preventing the valve body 14b of the first expansion valve 14 from closing the expansion valve passage 14a too much. In this embodiment, as shown in FIG. 14, when it is determined that the compressor 11 is intermittently operated, the first expansion valve 14 is opened by opening the bypass passage 14d. Suppressing the expansion valve 14 from being throttled too much is suppressed.

  As shown in FIG. 15, the bypass passage 14d is a refrigerant passage through which the refrigerant flows by bypassing a portion where the valve element 14b is disposed in the expansion valve passage 14a (main passage). The bypass valve element 14e changes the passage opening (throttle opening) of the bypass passage 14d. The bypass electric actuator 14f is an electromagnetic valve that drives the bypass valve element 14e. The operation of the bypass electric actuator 14 f is controlled by a control signal output from the control device 50.

  The bypass valve element 14e and the bypass electric actuator 14f constitute a bypass opening / closing mechanism that opens and closes the bypass passage 14d.

  As shown in FIG. 14, when it is determined in step S540 that the compressor 11 is not operating intermittently and is operating normally (S540: NO), the process proceeds to step S542. On the other hand, when it determines with the compressor 11 being intermittently operated (S540: YES), it progresses to step S562.

  In step S542, the bypass passage 14d is closed by the bypass valve element 14e, and the process proceeds to step S550 (bypass mechanism = valve closed). In step S550, the temporary expansion valve instruction opening EVHn_t calculated in step S530 is determined as the expansion valve instruction opening EVHn.

  Thereby, since the supercooling degree of the refrigerant flowing into the first expansion valve 14 approaches the target supercooling degree, the coefficient of performance (COP) of the cycle approaches the maximum value.

  On the other hand, in step S562, the bypass passage 14d is opened by the bypass valve element 14e, and the process proceeds to step S550 (bypass mechanism = valve open). As a result, when the compressor 11 is intermittently operated, the opening of the expansion valve 14 is larger than when the compressor 11 is normally operated, so the opening of the first expansion valve 14 is reduced. It can suppress that it is too much.

  In the present embodiment, as described in step S50, the control device 50 controls the operation of the valve body 14b of the first expansion valve 14 based on the degree of supercooling of the refrigerant that has flowed out of the indoor condenser 12. The control device 50 closes the bypass passage 14d of the first expansion valve 14 when performing the continuous operation control of the compressor 11, and performs the intermittent operation control of the compressor 11 when performing the intermittent operation control of the compressor 11. The operation of the bypass valve element 14e of the first expansion valve 14 is controlled so as to open the bypass passage 14d (steps S510 to S540, S542, and S562).

  According to this, when intermittent operation control of the compressor 11 is performed, the first expansion valve 14 controls the operation of the first expansion valve 14 based on the degree of supercooling of the refrigerant flowing out from the indoor condenser 12. It can suppress that a refrigerant | coolant flow is restrict | squeezed too much.

(Fourth embodiment)
In the above embodiment, the intermittent operation of the compressor 11 is performed in the heating mode, but in this embodiment, the intermittent operation of the compressor 11 is performed in the cooling mode as shown in FIG.

  The control signal output to the second expansion valve 19 in the cooling mode is determined so that the degree of supercooling of the refrigerant flowing into the second expansion valve 19 approaches the target degree of supercooling. The target degree of supercooling is determined so that the coefficient of performance (COP) of the cycle approaches the maximum value.

  Specifically, an instruction opening degree EVCn (hereinafter referred to as an expansion surface instruction opening degree) of the second expansion valve 19 is determined by executing the control process shown in the flowchart of FIG.

First, in step S810, the deviation Sn between the target supercooling degree SCOcool of the outlet side refrigerant of the outdoor heat exchanger 15 and the estimated value SCcool of the subcooling degree of the outlet side refrigerant of the outdoor heat exchanger 15 is calculated based on the following formula F8. calculate.
Sn = SCOcool-SCcool (F8)
The target supercooling degree SCOcool of the refrigerant on the outlet side of the outdoor heat exchanger 15 is referred to a control map stored in advance in the control device 50 based on values such as the intake air temperature and the target outlet temperature TAO of the outdoor heat exchanger 15. Is calculated.

  The intake air temperature of the outdoor heat exchanger 15 is substantially the same as the outdoor air temperature Tam. Therefore, in this embodiment, the outside air temperature Tam detected by the outside air sensor is used as the intake air temperature of the outdoor heat exchanger 15.

The estimated value SC of the degree of supercooling of the refrigerant on the outlet side of the outdoor heat exchanger 15 is calculated and estimated using the following formula F9 based on the pressure and temperature Th2 of the refrigerant flowing out of the outdoor heat exchanger 15.
SC = Ths-Th2 (F9)
Ths is a refrigerant saturation temperature corresponding to the pressure of the refrigerant flowing out of the outdoor heat exchanger 15. In the cooling mode, since the first refrigerant passage 13 is fully opened by the first expansion valve 14, the refrigerant pressure Ph detected by the high-pressure refrigerant pressure sensor 54 is equal to the refrigerant pressure flowing out of the outdoor heat exchanger 15. It will be almost the same. Therefore, in the present embodiment, the refrigerant pressure Ph detected by the high-pressure refrigerant pressure sensor 54 is used as the refrigerant pressure flowing out of the outdoor heat exchanger 15.

  In the subsequent step S820, the operation amount ΔEVC of the second expansion valve 19 is calculated with reference to the control map stored in advance in the control device 50 based on the deviation Sn calculated in step S810. Specifically, the operation amount ΔEVC of the second expansion valve 19 is calculated so that the value of the deviation Sn approaches 0.

In the subsequent step S830, a temporary expansion valve instruction opening EVCn_t is calculated based on the following formula F10. The temporary expansion valve instruction opening degree EVCn_t is a temporary value of the expansion valve instruction opening degree EVCn.
EVCn_t = EVCn−1 + ΔEVC (F10)
EVCn-1 is the previous expansion valve instruction opening.

  In subsequent step S840, it is determined whether or not the compressor 11 is intermittently operated. When it is determined that the compressor 11 is intermittently operated, the process proceeds to step S850, where it is determined that the compressor 11 is not intermittently operated. If so, the process proceeds to step S860.

  In step S850, the temporary expansion valve instruction opening EVCn_t calculated in step S830 is determined as the expansion valve instruction opening EVCn. Thereby, since the supercooling degree of the refrigerant flowing into the second expansion valve 19 approaches the target supercooling degree, the coefficient of performance (COP) of the cycle approaches the maximum value.

On the other hand, in step S860, a lower limit value EVCmin of the expansion valve instruction opening is calculated based on the following formula F11.
EVCmin = EVCmin_SPD + EVCmin_TAM + EVCmin_Ph (F11)
EVCmin_SPD is calculated with reference to a control map (FIG. 17A) stored in advance in the control device 50 based on the value of the wind speed SPD in front of the outdoor heat exchanger 15. The front wind speed SPD of the outdoor heat exchanger 15 is calculated based on the rotational speed of the blower fan that blows air to the outdoor heat exchanger 15 and the vehicle speed. As the wind speed SPD on the front surface of the outdoor heat exchanger 15 is higher, the refrigerant is more easily condensed in the outdoor heat exchanger 15, so the value of EVCmin_SPD is increased.

  EVHmin_TAM is calculated with reference to a control map (FIG. 17B) stored in advance in the control device 50 based on the value of the outdoor heat exchanger 15 front air temperature TAM. In the present embodiment, the outdoor air temperature Tam detected by the outdoor air sensor is used as the front air temperature TAM of the outdoor heat exchanger 15. As the air temperature TAM on the front side of the outdoor heat exchanger 15 is lower, the refrigerant is more easily condensed in the outdoor heat exchanger 15, so the value of EVCmin_SPD is increased.

  EVHmin_Ph is calculated with reference to a control map (FIG. 17C) stored in advance in the control device 50 based on the value of the pressure of the refrigerant flowing out of the outdoor heat exchanger 15 (high pressure of the refrigeration cycle). The In the present embodiment, the refrigerant pressure Ph detected by the high-pressure refrigerant pressure sensor 54 is used as the refrigerant pressure flowing out of the outdoor heat exchanger 15. The higher the pressure Ph of the refrigerant flowing out of the outdoor heat exchanger 15, the easier it is for the refrigerant to condense in the outdoor heat exchanger 15, so the value of EVCmin_SPD is increased.

In the subsequent step S870, the expansion valve instruction opening EVCn is calculated based on the following formula F12.
EVCn = MAX [EVCn_t, EVCmin] (F12)
MAX [EVCn_t, EVCmin] in Formula F12 means the larger value of EVCn_t and EVCmin.

  Thereby, when the compressor 11 is intermittently operated, the opening degree of the second expansion valve 19 becomes equal to or higher than the lower limit value EVCmin, so that the opening degree of the second expansion valve 19 can be suppressed from being reduced too much. Therefore, it is possible to suppress the liquid refrigerant from staying in the outdoor heat exchanger 15, and thus it is possible to suppress a shortage of the flow rate of the refrigerant flowing into the indoor evaporator 20. Therefore, the temperature distribution and temperature rise of the air blown from the indoor evaporator 20 can be suppressed, and the passenger comfort can be improved.

  In the present embodiment, as described in step S80, the control device 50 switches between continuous operation control and intermittent operation control of the compressor 11 in the cooling mode.

  According to this, even if the intermittent operation control of the compressor 11 is performed in the cooling mode, it is possible to suppress the liquid refrigerant from staying in the outdoor heat exchanger 15, so that the flow rate of the refrigerant flowing into the indoor evaporator 20 is insufficient. Can be suppressed. Therefore, the temperature distribution and temperature rise of the air blown from the indoor evaporator 20 can be suppressed, and the passenger comfort can be improved.

(Other embodiments)
The above embodiments can be combined as appropriate. The above embodiment can be variously modified as follows, for example.

  (1) In each of the above-described embodiments, the example in which the heating mode, the cooling mode, and the dehumidifying heating mode are switched by the operation signal of the A / C switch is described, but the present invention is not limited to this. For example, an operation mode setting switch for setting each operation mode may be provided on the operation panel, and the heating mode, the cooling mode, and the dehumidifying heating mode may be switched according to an operation signal of the operation mode setting switch.

  (2) In each of the embodiments described above, the control device is one of the air passage of the indoor condenser 12 and the heater core 34 and the cold air bypass passage 35 in each operation mode of the heating mode, the cooling mode, and the dehumidifying heating mode. However, the operation of the air mix door 36 is not limited to this.

  For example, the air mix door 36 may open both the air passage of the indoor condenser 12 and the heater core 34 and the cold air bypass passage 35. The temperature of the air blown into the vehicle interior may be adjusted by adjusting the air volume ratio between the air volume that passes through the air passages of the indoor condenser 12 and the heater core 34 and the air volume that passes through the cold air bypass passage 35. Good. Such temperature adjustment is effective in that it is easy to finely adjust the temperature of the air blown into the passenger compartment.

  (3) In each of the above-described embodiments, the heater core 34 is arranged inside the indoor air conditioning unit 30. However, when an external heat source such as an engine is insufficient, the heater core 34 is abolished or an electric heater or the like is used. You may make it replace with.

  (4) In each of the above-described embodiments, the example in which the refrigeration cycle apparatus 10 is applied to the vehicle air conditioner 1 has been described. However, the present invention is not limited to this. For example, the refrigeration cycle apparatus 10 is applied to a stationary air conditioner or the like. May be.

11 Compressor 12 Indoor condenser (condenser)
14 First expansion valve (pressure reduction means)
20 Indoor evaporator (evaporator)
50 Control device (control means)
32 Blower (Blower means)
14b Valve body (cross-sectional area change mechanism)
14a Expansion valve passage (main passage, refrigerant passage)
14d Bypass passage (refrigerant passage)
14e Bypass valve body (cross-sectional area change mechanism)

Claims (8)

A compressor (11) for compressing and discharging the refrigerant;
Condensers (12, 15) for radiating the refrigerant discharged from the compressor (11) to condense the refrigerant;
A refrigerant passage (14a, 14d, 19a) through which the refrigerant condensed in the condenser (12, 15) flows and a cross-sectional area changing mechanism (14b, 14a, 14a, 19a) for changing the cross-sectional area of the refrigerant passage (14a, 14d, 19a). 14e, 19b), and decompression means (14, 19) for decompressing the refrigerant condensed in the condenser (12),
An evaporator (20) for absorbing heat to the refrigerant decompressed by the decompression means (14, 19) and evaporating the refrigerant;
Control means (50) for controlling the operation of the compressor (11) and the cross-sectional area changing mechanism (14b, 14e, 19b),
The control means (50)
When it is necessary to drive the compressor (11) at a rotation speed equal to or higher than the lower limit rotation speed, continuous operation control for continuously driving the compressor (11) is performed,
When it is necessary to drive the compressor (11) at a rotational speed lower than the lower limit rotational speed, intermittent operation control is performed to repeatedly drive and stop the compressor (11),
When the intermittent operation control is performed, the cross-sectional area changing mechanism (the cross-sectional area changing mechanism ( 14b, 14e, and 19b) are controlled. The control means (50) calculates the instruction opening degree (EVHn_t, EVCn_t) of the decompression means (14, 19) based on the degree of supercooling of the refrigerant flowing out of the condenser (12, 15),
When the intermittent operation control is performed, the lower limit value (EVHmin, EVCmin) of the indicated opening is calculated regardless of the degree of supercooling of the refrigerant that has flowed out of the condenser (12, 15). The refrigeration cycle apparatus according to claim 1. Blower means (32) for blowing air to the condenser (12),
The condenser (12) is configured to exchange heat between the refrigerant discharged from the compressor (11) and the air blown by the blowing means (32).
The control means (50), when performing the intermittent operation control, the air flow rate (BLW) of the air blowing means (32), the temperature (TIN) of the air sucked into the condenser (12), the condensation The refrigeration cycle apparatus according to claim 2, wherein a lower limit value (EVHmin) of the indicated opening is determined based on at least one of the pressures (Ph) of the refrigerant flowing into the vessel (12). The control means (50)
When performing the continuous operation control, the instruction opening degree (EVHn_t) of the pressure reducing means (14) is calculated based on the degree of supercooling of the refrigerant flowing out of the condenser (12),
When the intermittent operation control is performed, the instruction opening degree (EVHON-OFF) of the pressure reducing means (14) is calculated irrespective of the degree of supercooling of the refrigerant flowing out of the condenser (12). The refrigeration cycle apparatus according to claim 1, wherein: Blower means (32) for blowing air to the condenser (12),
The condenser (12) is configured to exchange heat between the refrigerant discharged from the compressor (11) and the air blown by the blowing means (32).
The control means (50) sucks the indicated opening degree (EVHON-OFF) into the blowing amount (BLW) of the blowing means (32) and the condenser (12) when performing the intermittent operation control. 5. The refrigeration cycle apparatus according to claim 4, wherein the refrigeration cycle apparatus determines the temperature based on at least one of a temperature (TIN) of the air and a pressure (Ph) of the refrigerant flowing into the condenser (12). The refrigerant passages (14a, 14d) are a main passage (14a) and a bypass passage (14d),
The cross-sectional area changing mechanism (14b, 14e) includes a valve body (14b) that changes the cross-sectional area of the main passage (14a) and a bypass valve body (14e) that changes the cross-sectional area of the bypass passage (14d). And
The bypass passage (14d) is a passage through which the refrigerant flows by bypassing a portion of the main passage (14a) whose cross-sectional area is changed by the valve body (14b),
The control means (50)
Controlling the operation of the valve body (14b) based on the degree of supercooling of the refrigerant flowing out of the condenser (12),
When the continuous operation control is performed, the bypass passage (14d) is closed, and when the intermittent operation control is performed, the bypass valve element (14e) is operated so as to open the bypass passage (14d). The refrigeration cycle apparatus according to claim 1, wherein the refrigeration cycle apparatus is controlled. The condenser (12) is a heating heat exchanger that heats the air by exchanging heat between the air blown toward the air-conditioning target space and the refrigerant,
The said control means (50) switches the said continuous operation control and the said intermittent operation control in the heating mode in which the said condenser (12) heats the said air, The any one of Claim 1 thru | or 6 characterized by the above-mentioned. The refrigeration cycle apparatus described in 1. The evaporator (20) is a cooling heat exchanger that cools the air by exchanging heat between the air blown toward the air-conditioning target space and the refrigerant,
The said control means (50) switches the said continuous operation control and the said intermittent operation control in the cooling mode in which the said evaporator (20) cools the said air, The any one of Claim 1 thru | or 6 characterized by the above-mentioned. The refrigeration cycle apparatus described in 1.

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