WO2018088025A1 - Refrigeration cycle device - Google Patents

Abstract

A refrigeration cycle device is provided with: a decompression device control unit (40b) for controlling the operation of a decompression device; a target supercooling degree determination unit (S9) for determining the target supercooling degree (SCO) of refrigerant flowing out of a heating heat exchanger; and a low-flow-rate operation determination unit (S41-S43) for determining that the circulation refrigerant flow rate of the refrigerant circulating in the cycle has reached a low-flow-rate operation that is less than a preset reference flow rate. The decompression device control unit controls the operation of the decompression device so that the refrigerant flowing out of the heating heat exchanger approaches the target supercooling degree (SCO), and the target supercooling degree determination unit reduces the target supercooling degree (SCO) when the low-flow-rate operation determination unit has determined the cycle to be in the low-flow-rate operation. Expansion of the range in which the temperature distribution of ventilation air heated by an indoor condenser occurs can thereby be suppressed.

Description

Refrigeration cycle equipment Cross-reference of related applications

This application is based on Japanese Patent Application No. 2016-220487 filed on November 11, 2016, the disclosure of which is incorporated into this application by reference.

The present disclosure relates to a refrigeration cycle apparatus applied to an air conditioner.

Conventionally, Patent Document 1 discloses a vapor compression refrigeration cycle apparatus applied to a vehicle air conditioner. The refrigeration cycle apparatus of Patent Document 1 includes an indoor condenser. The indoor condenser is a heating heat exchanger that heats the blown air by causing heat exchange between the high-pressure refrigerant discharged from the compressor and the blown air blown into the vehicle interior during the heating operation for heating the passenger compartment. is there.

Furthermore, in the refrigeration cycle apparatus of Patent Document 1, an expansion valve that is a decompression device that decompresses high-pressure refrigerant so that the refrigerant flowing out of the indoor condenser becomes a liquid-phase refrigerant having a predetermined degree of supercooling during heating operation. The operation is controlled. Thereby, in the refrigerating cycle device of patent documents 1, it is going to improve a coefficient of performance (COP) of a cycle.

JP-A-6-347129

According to the study of the inventors of the present disclosure, as in the refrigeration cycle device of Patent Document 1, when the operation of the expansion valve is controlled so that the refrigerant flowing out of the indoor condenser becomes a liquid phase refrigerant having a degree of supercooling, A temperature change occurs in the refrigerant flowing through the indoor condenser. For this reason, temperature distribution tends to occur in the blown air heated by the indoor condenser.

Furthermore, when the flow rate of the circulating refrigerant circulating through the refrigeration cycle apparatus decreases and the refrigerant is started to be supercooled at the upstream side of the refrigerant flow of the indoor condenser, the blown air heated by the indoor condenser is reduced. The range in which the temperature distribution occurs is expanded. The expansion of the range in which such a temperature distribution occurs is a cause of impairing the passenger's comfortable feeling of heating.

This indication aims at providing the refrigerating-cycle apparatus which can suppress that the range which the temperature distribution of the ventilation air ventilated by the air-conditioning object space produces expands in view of the said point.

A refrigeration cycle apparatus according to one feature example of the present disclosure heat-exchanges a compressor that compresses and discharges a refrigerant, and a high-pressure refrigerant discharged from the compressor and blown air that is blown into an air-conditioning target space. A heat exchanger for heating air, a decompressor for decompressing the refrigerant flowing out of the heat exchanger for heating, an outdoor heat exchanger for exchanging heat between the low-pressure refrigerant decompressed by the decompressor and the outside air, and a decompression The pressure reducing device control unit for controlling the operation of the device, the target subcooling degree determining unit for determining the target subcooling degree of the refrigerant flowing out from the heating heat exchanger, and the circulating refrigerant flow rate of the refrigerant circulating in the cycle are determined in advance. A low flow rate operation determination unit that determines that the low flow rate operation is lower than the reference flow rate.

The decompression device control unit controls the operation of the decompression device so that the refrigerant flowing out from the heat exchanger for heating approaches the target supercooling degree. It is a refrigeration cycle apparatus that reduces the target degree of supercooling when it is determined that the flow rate operation is in progress.

According to this, when it is determined that the low-flow operation is being performed, the target supercooling degree determination unit lowers the target supercooling degree, so that the refrigerant in the upstream portion of the refrigerant flow of the heating heat exchanger It is possible to suppress the start of supercooling. Accordingly, it is possible to suppress the expansion of the range in which the temperature distribution of the blown air heated by the heating heat exchanger occurs even during the low flow rate operation.

Furthermore, when it is not determined that the operation is at a low flow rate, the refrigeration cycle apparatus can exhibit a high COP by determining the target supercooling degree (SCO) so as to improve the COP.

It is a whole block diagram which shows the refrigerant | coolant flow at the time of the air_conditioning | cooling mode and serial dehumidification heating mode of the refrigerating-cycle apparatus of one Embodiment. It is a whole block diagram which shows the flow of the refrigerant | coolant at the time of the parallel dehumidification heating mode of the refrigerating-cycle apparatus of one Embodiment. It is a whole lineblock diagram showing a refrigerant flow at the time of heating mode of a refrigerating cycle device of one embodiment. It is a block diagram which shows the electric control part of the vehicle air conditioner of one Embodiment. It is a flowchart which shows the control processing of the vehicle air conditioner of one Embodiment. It is a flowchart which shows a part of control process of the vehicle air conditioner of one Embodiment. It is a control characteristic diagram for determining a target supercooling degree at the time of normal heating mode. It is a control characteristic diagram for determining a target supercooling degree at the time of low flow rate heating mode.

1 to 8 will be used to describe an embodiment of the present disclosure. In the present embodiment, the refrigeration cycle apparatus 10 according to the present disclosure is applied to a vehicle air conditioner 1 for a hybrid vehicle that obtains driving force for traveling from an internal combustion engine (that is, an engine) and a traveling electric motor. The refrigeration cycle apparatus 10 fulfills a function of cooling or heating the air blown into the vehicle interior, which is the air-conditioning target space, in the vehicle air conditioner 1.

The refrigeration cycle apparatus 10 includes a cooling mode refrigerant circuit (see FIG. 1), a serial dehumidifying and heating mode refrigerant circuit (see FIG. 1), a parallel dehumidifying and heating mode refrigerant circuit (see FIG. 2), and a heating mode refrigerant circuit (see FIG. 1). 3) can be switched. In FIGS. 1 to 3, the refrigerant flow in each operation mode is indicated by a thick solid arrow.

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

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

In the refrigeration cycle apparatus 10, the compressor 11 sucks refrigerant, compresses it, and discharges it. The compressor 11 is arrange | positioned in the hood of a vehicle. The compressor 11 is an electric compressor that rotationally drives a fixed capacity type compression mechanism with a fixed discharge capacity by an electric motor. The compressor 11 has its rotational speed (that is, refrigerant discharge capacity) controlled by a control signal output from an air conditioning control device 40 described later.

The refrigerant inlet side of the indoor condenser 12 is connected to the discharge port of the compressor 11. The indoor condenser 12 is arrange | positioned in the air-conditioning case 31 of the indoor air-conditioning unit 30 of the vehicle air conditioner 1 mentioned later. The indoor condenser 12 is a heating heat exchanger that heats the blown air by exchanging heat between the high-pressure refrigerant discharged from the compressor 11 and blown air that has passed through the indoor evaporator 23 described later.

In the present embodiment, a so-called tank-and-tube heat exchanger having a plurality of refrigerant tubes, distribution tanks, collecting tanks, and the like is employed as the indoor condenser 12.

The refrigerant tube is a tubular member that allows the refrigerant to flow therethrough. The plurality of refrigerant tubes are stacked in the longitudinal direction of the collecting tank and the distributing tank. Between the adjacent refrigerant tubes, an air passage through which blown air is circulated is formed, and fins that promote heat exchange between the refrigerant and the blown air are arranged. Thereby, the heat exchange part which heat-exchanges a refrigerant | coolant and blowing air is formed.

A collecting tank and a distribution tank are connected to both ends of the plurality of refrigerant tubes. A refrigerant inlet is formed in the distribution tank. Therefore, the refrigerant flowing into the distribution tank from the refrigerant inlet is distributed to the plurality of refrigerant tubes. A refrigerant outlet is formed in the collecting tank. Therefore, the refrigerant collected in the collecting tank from the plurality of refrigerant tubes flows out from the refrigerant outlet.

That is, the indoor condenser 12 of the present embodiment is configured as a so-called one-pass type heat exchanger in which the refrigerant flows in one direction from the distribution tank side toward the collecting tank side in the plurality of refrigerant tubes. In the present embodiment, the collecting tank is disposed on the lower side in the vertical direction than the distributing tank.

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

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

The inlet side of the first expansion valve 14a is connected to one outlet of the first three-way joint 13a. One inlet of the second three-way joint 13b is connected to the other outlet of the first three-way joint 13a. A first on-off valve 15a is disposed in the first refrigerant passage 18a that connects the other outlet side of the first three-way joint 13a and one inlet side of the second three-way joint 13b.

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

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

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

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

The first and second expansion valves 14a and 14b can switch the refrigerant circuit in each operation mode described above by the fully open function and the fully closed function. Therefore, the first and second expansion valves 14a and 14b also have a function as a refrigerant circuit switching device. The operations of the first and second expansion valves 14 a and 14 b are controlled by a control signal (control pulse) output from the air conditioning control device 40.

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

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

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

A second on-off valve 15b that opens and closes the second refrigerant passage 18b is disposed in the second refrigerant passage 18b that connects the other outlet side of the third three-way joint 13c and one inlet side of the fourth three-way joint 13d. Has been.

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

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

The indoor evaporator 23 is disposed in the air conditioning case 31 of the indoor air conditioning unit 30. The indoor evaporator 23 heat-exchanges the low-pressure refrigerant decompressed by the second expansion valve 14b and the blown air blown from the blower 32 at least in the cooling mode, evaporates the low-pressure refrigerant, and absorbs heat to the low-pressure refrigerant. It is a heat exchanger for cooling which cools blowing air by making it exhibit.

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

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

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

The heater core 39 is a heat exchanger for auxiliary heating that heats the blown air by heat exchange between the engine cooling water and the blown air after passing through the indoor evaporator 23. The heater core 39 is connected to an engine coolant circuit that circulates engine coolant.

The air conditioning case 31 forms an air passage for blown air to be blown into the passenger compartment, and is formed of a resin (for example, polypropylene) having a certain degree of elasticity and excellent strength. On the most upstream side of the air flow of the air conditioning case 31, an inside / outside air switching device 33 that switches and introduces inside air (vehicle compartment air) and outside air (vehicle compartment outside air) into the air conditioning case 31 is disposed.

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

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

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

In the air conditioning case 31, a bypass passage 35 is provided in which the blown air that has passed through the indoor evaporator 23 flows through the heater core 39 and the indoor condenser 12. An air mix door 34 is disposed on the downstream side of the blower air flow of the indoor evaporator 23 in the air conditioning case 31 and on the upstream side of the blower air flow of the heater core 39 and the indoor condenser 12.

The air mix door 34 adjusts the air volume ratio between the air volume of the blown air passing through the indoor condenser 12 and the air volume of the blown air passing through the bypass passage 35 among the blown air after passing through the indoor evaporator 23. It is an adjustment unit. The air mix door 34 is driven by an electric actuator for the air mix door. The operation of the electric actuator is controlled by a control signal output from the air conditioning controller 40.

On the downstream side of the blast air flow of the indoor condenser 12 and the bypass passage 35, the blast air heated by exchanging heat with the refrigerant in the heater core 39 and the indoor condenser 12 and the blast air not heated through the bypass passage 35 A merge space 36 in which air merges is formed. For this reason, the air mix door 34 adjusts the air volume ratio, so that the temperature of the blown air that merges in the merge space 36 is adjusted.

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

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

Here, in the air conditioning case 31 of the present embodiment, the face opening hole 37b and the defroster opening hole 37c are arranged on the upper side in the vertical direction from the foot opening hole 37a.

For this reason, the blast air flowing out from the face opening hole 37b and the defroster opening hole 37c is mainly above the intermediate part in the vertical direction in the heat exchanging part of the indoor condenser 12, that is, on the side closer to the distribution tank. It tends to be blown air heated at the site. In other words, the blown air flowing out from the face opening hole 37b and the defroster opening hole 37c is heated in the heat exchange part of the indoor condenser 12 mainly at a part upstream of the refrigerant flow from the intermediate part in the vertical direction. It becomes blowing air.

On the other hand, the blown air that flows out from the foot opening hole 37a is heated in a portion of the heat exchanger of the indoor condenser 12 that is mainly below the intermediate portion in the vertical direction, that is, on the side closer to the collecting tank. It tends to be blown air. In other words, the blown air that flows out from the foot opening hole 37a is blown air that is heated in a portion of the heat exchanger of the indoor condenser 12 that is mainly downstream of the refrigerant flow from the intermediate portion in the vertical direction.

Further, on the upstream side of the blowing air flow of the foot opening hole 37a, the face opening hole 37b, and the defroster opening hole 37c, the foot door 38a for adjusting the opening area of the foot opening hole 37a and the opening area of the face opening hole 37b are adjusted respectively. A defroster door 38c for adjusting the opening area of the face door 38b and the defroster opening hole 37c is disposed.

The foot door 38a, the face door 38b, and the defroster door 38c are blowing mode doors that open and close the opening holes 37a to 37c to switch the blowing mode, and constitute a blowing mode switching device. Each of the doors 38a to 38c is rotated by an electric actuator 61 for the blowout mode door via a link mechanism or the like. The operation of the electric actuator 61 is controlled by a control signal output from the air conditioning controller 40.

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

Also, the blowing mode switched by the blowing mode switching device specifically includes a face mode, a bi-level mode, a foot mode, and the like.

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

Therefore, the face mode of the present embodiment is a first blow-out mode in which blown air heated mainly at a portion upstream of the refrigerant flow from the intermediate portion in the vertical direction is blown out of the heat exchange portion of the indoor condenser 12. is there. In addition, the foot mode of the present embodiment is a second blowing mode in which blown air heated mainly at the downstream side of the refrigerant flow with respect to the intermediate portion in the vertical direction is blown out of the heat exchange portion of the indoor condenser 12. is there.

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

Next, the electric control unit of this embodiment will be described with reference to FIG. The air conditioning control device 40 includes a known microcomputer including a CPU, a ROM, a RAM, and the like and peripheral circuits thereof. And various calculations and processes are performed based on the air conditioning control program stored in the ROM, and the operation of various air conditioning control devices connected to the output side is controlled.

Connected to the output side of the air conditioning controller 40 are the compressor 11, the first and second expansion valves 14a and 14b, the first and second on-off valves 15a and 15b, the outside air fan 20a, the blower 32, and other electric actuators. Has been.

On the input side of the air conditioning control device 40, there are an inside air temperature sensor 41, an outside air temperature sensor 42, a solar radiation sensor 43, an inflow air temperature sensor 44, first to third refrigerant temperature sensors 45a to 45c, a high pressure sensor 46a, an outdoor unit pressure sensor. 46b, an evaporator temperature sensor 47, an air conditioning air temperature sensor 48, and the like are connected. The air conditioning control device 40 receives detection signals from these air conditioning control sensor groups.

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

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

The high-pressure sensor 46a is a high-pressure refrigerant pressure detection unit that detects the high-pressure side refrigerant pressure Ph in the refrigerant passage from the discharge port side of the compressor 11 to the inlet side of the first expansion valve 14a. The outdoor unit pressure sensor 46 b is an outdoor unit pressure detection unit that detects the outdoor refrigerant pressure Ps that has flowed out of the outdoor heat exchanger 20. The evaporator temperature sensor 47 is an evaporator temperature detector that detects a refrigerant evaporation temperature (evaporator temperature) Tefin in the indoor evaporator 23. The air-conditioning air temperature sensor 48 is an air-conditioning air temperature detector that detects the temperature of the blown air TAV blown from the merge space 36 into the vehicle interior.

Further, as shown in FIG. 4, an operation panel 50 disposed near the instrument panel in the front of the passenger compartment is connected to the input side of the air conditioning control device 40, and various operation switches provided on the operation panel 50 are connected. The operation signal is input.

The various operation switches provided on the operation panel 50 include an operation switch, an auto switch, an operation mode switching switch, an air volume setting switch, a temperature setting switch, a blowing mode switching switch, and the like.

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

The air-conditioning control device 40 according to the present embodiment is configured such that a control unit that controls various control target devices connected to the output side thereof is integrally configured. However, the configuration controls the operation of each control target device. (Hardware and Software) constitutes a control unit that controls the operation of each control target device.

For example, the configuration (hardware and software) for controlling the refrigerant discharge capacity of the compressor 11 in the air conditioning control device 40 is the discharge capacity control unit 40a. The configuration for controlling the throttle opening degree of the first expansion valve 14a is a decompression device control unit 40b. The configuration for controlling the operation of the refrigerant circuit switching device such as the first and second on-off valves 15a and 15b is a refrigerant circuit control unit 40c. The configuration for controlling the blowing capacity of the outside air fan 20a is the outside air fan control unit 40d. The structure which controls the ventilation capability of the air blower 32 is the air blower control part 40e. The structure which controls the action | operation of the electric actuator 61 for blowing mode doors is the blowing mode control part 40f.

Next, the operation of this embodiment in the above configuration will be described. In the vehicle air conditioner 1 of the present embodiment, cooling, dehumidifying heating, and heating of the passenger compartment are performed. For this reason, in the refrigeration cycle apparatus 10, the operation in the cooling mode, the operation in the series dehumidification heating mode, the operation in the parallel dehumidification heating mode, and the operation in the heating mode can be switched.

These switching of each operation mode is performed by executing an air conditioning control program. The air conditioning control program is executed when the auto switch of the operation panel 50 is turned on (ON) and automatic control is set. The main routine of the air conditioning control program will be described using the flowchart of FIG. In addition, each control step shown in the flowchart of FIG. 5, FIG. 6 is the various function implementation | achievement part which the air-conditioning control apparatus 40 has.

First, in step S1 of FIG. 5, initialization such as initialization of flags and timers configured by the storage circuit of the air-conditioning control device 40, initial alignment of the stepping motor that constitutes the electric actuator described above, and the like is performed. In step S2, the detection signal of the air conditioning control sensor group and the operation signal of the operation panel 50 are read.

In step S3, based on the value of the detection signal and the operation signal read in step S2, a target blowing temperature TAO that is a target temperature of the blowing air blown into the vehicle interior is calculated based on the following Equation 1.
TAO = Kset × Tset−Kr × Tr−Kam × Tam−Ks × As + C (F1)
Here, Tset is the passenger compartment set temperature set by the temperature setting switch, Tr is the inside air temperature detected by the inside air temperature sensor 41, Tam is the outside air temperature detected by the outside air temperature sensor 42, and As is detected by the solar radiation sensor 43. Is the amount of solar radiation. Kset, Kr, Kam, Ks are control gains, and C is a correction constant.

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

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

In the state where the cooling mode is set by the operation mode changeover switch, when the target blowing temperature TAO is equal to or higher than the cooling reference temperature α and the outside air temperature Tam is equal to or lower than the dehumidifying heating reference temperature β. The operation in the parallel dehumidifying and heating mode is determined. Further, when the cooling mode is not set by the operation mode switch, the heating mode is determined.

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

Furthermore, when the operation mode is determined to be the heating mode in step S4, the air conditioning control device 40 executes a subroutine shown in FIG. Thereby, in the refrigeration cycle apparatus 10 of the present embodiment, the normal heating mode and the low flow rate heating mode are switched. The low flow rate heating mode is a heating mode that is executed when a low flow rate operation is performed in which the circulating refrigerant flow rate of the refrigerant circulating in the cycle is lower than a predetermined reference flow rate.

In step S41 of FIG. 6, it is determined whether or not the outside air temperature Tam is equal to or higher than the reference outside air temperature KTam. When the outside air temperature Tam is equal to or higher than the reference outside air temperature KTam during the heating operation, the heat load of the refrigeration cycle apparatus 10 becomes small, and the circulating refrigerant flow rate tends to decrease. Therefore, in the present embodiment, in the heating mode, the outside air temperature at which the circulating refrigerant flow rate can be equal to or less than the reference flow rate is set as the reference outside air temperature KTam.

When it is determined in step S41 that the outside air temperature Tam is equal to or higher than the reference outside air temperature Ktam, the process proceeds to step S42. Further, when it is determined in step S41 that the outside air temperature Tam is not equal to or higher than the reference outside air temperature KTam, the process proceeds to step S45.

In step S42, it is determined whether the inflow air temperature TAin of the blown air flowing into the indoor condenser 12 is equal to or higher than the reference inflow temperature KTAin. When the inflow air temperature TAin is equal to or higher than the reference inflow temperature KTAin, the heat load of the refrigeration cycle apparatus 10 is reduced, and the circulating refrigerant flow rate is likely to be reduced. Therefore, in the present embodiment, the inflow air temperature at which the circulating refrigerant flow rate can be equal to or lower than the reference flow rate is set as the reference inflow temperature KTAin in the heating mode.

When it is determined in step S42 that the inflow air temperature TAin is equal to or higher than the reference inflow temperature KTAin, the process proceeds to step S43. If it is determined in step S42 that the inflow air temperature TAin is not equal to or higher than the reference inflow temperature KTAin, the process proceeds to step S45.

In step S43, it is determined whether or not the refrigerant discharge capacity (specifically, the rotation speed Nc) of the compressor 11 is equal to or lower than a predetermined reference discharge capacity (specifically, the reference rotation speed KNc). In the present embodiment, the rotation speed at which the circulating refrigerant flow rate can be equal to or lower than the reference flow rate is set to the reference rotation speed KNc in the heating mode.

When it is determined in step S43 that the rotation speed Nc is equal to or less than the reference rotation speed KNc, the process proceeds to step S44. If it is determined in step S43 that the rotation speed Nc is not less than or equal to the reference rotation speed KNc, the process proceeds to step S45.

In step S44, it is determined to execute the low flow rate heating mode as the heating mode, and the process returns to the main routine. In step S45, it decides to perform normal heating mode as heating mode, and returns to a main routine. Therefore, the control steps S41 to S43 of the present embodiment are a low flow rate operation determination unit that determines that the low flow rate operation is performed in which the circulating refrigerant flow rate is lower than a predetermined reference flow rate.

Next, in steps S5 to S12 shown in FIG. 5, control states of various air conditioning control devices are determined. In step S5, according to each operation mode, the ventilation capability of the air blower 32, ie, the control voltage applied to the electric motor of the air blower 32, is determined. The control voltage output to the blower 32 is determined with reference to a control map stored in advance in the air conditioning control device 40 based on the target blowing temperature TAO.

In this control map, the air flow rate is increased in the extremely low temperature range (maximum cooling range) and the extremely high temperature range (maximum heating range) of the target blowing temperature TAO in the operation mode excluding the low flow rate heating mode, and the target blowing temperature TAO is set to the intermediate temperature. The control voltage is determined so as to reduce the air volume as it approaches the area.

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

In this control map, the control voltage is determined so as to increase the air flow rate of the outside air fan 20a as the outside air temperature Tam decreases in the operation modes other than the low flow rate operation mode.

In step S7, a suction mode, that is, a control signal output to the electric actuator for the inside / outside air switching door is determined. The suction mode is determined with reference to a control map stored in advance in the air conditioning control device 40 based on the target outlet temperature TAO. In this control map, the outside air mode for introducing outside air is basically given priority. However, when the target blowing temperature TAO is in the extremely low temperature range or the extremely high temperature range, the inside air mode for introducing the inside air is selected. .

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

In this control map, as the target blowing temperature TAO rises from the low temperature range to the high temperature range, the blowing mode is sequentially switched from the face mode to the bi-level mode to the foot mode. Accordingly, it is easy to select the face mode mainly in summer, the bi-level mode mainly in spring and autumn, and the foot mode mainly in winter.

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

In step S10, the open / close state of the first and second on-off valves 15a and 15b, that is, the control voltage output to the first and second on-off valves 15a and 15b is determined according to each operation mode.

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

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

In step S13, control signals and control voltages are output from the air-conditioning control device 40 to various air-conditioning control devices so that the control states determined in the above-described steps S6 to S12 are obtained. In continuing step S14, it waits for control period (tau), and if progress of control period (tau) is determined, it will return to step S2. Below, the detailed operation | movement of each operation mode is demonstrated.

(A) Cooling mode In the cooling mode, the air-conditioning control device 40 opens the first expansion valve 14a and opens the second expansion valve 14b in a throttle state that exerts a pressure reducing action. Further, the air conditioning control device 40 closes the first on-off valve 15a and closes the second on-off valve 15b. In addition, the air conditioning control device 40 displaces the air mix door 34 so that the ventilation path on the heater core 39 and the indoor condenser 12 side is fully closed and the bypass passage 35 side is fully opened.

Thus, in the cooling mode, as indicated by the thick solid arrow in FIG. 1, the compressor 11 (→ the indoor condenser 12 → the first expansion valve 14a) → the outdoor heat exchanger 20 → the second expansion valve 14b → the indoor evaporator. A vapor compression refrigeration cycle is constructed in which the refrigerant circulates in the order of 23 → evaporation pressure regulating valve 26 → accumulator 24 → compressor 11.

In this cycle configuration, the air conditioning controller 40 determines the refrigerant discharge capacity of the compressor 11, that is, the control signal output to the electric motor of the compressor 11. Specifically, the operation of the compressor 11 is controlled so that the blown air blown from the indoor evaporator 23 becomes the target evaporator temperature TEO. The target evaporator temperature TEO is determined on the basis of the target outlet temperature TAO with reference to a control map stored in the air conditioning control device 40 in advance.

In this control map, it is determined that the target evaporator temperature TEO decreases as the target outlet temperature TAO decreases. Furthermore, the target evaporator temperature TEO is determined within a range (specifically, 1 ° C. or higher) in which frost formation in the indoor evaporator 23 can be suppressed.

Also, the air conditioning control device 40 adjusts the throttle opening of the second expansion valve 14b so that the degree of supercooling of the refrigerant flowing into the second expansion valve 14b becomes the target degree of supercooling for cooling. The target supercooling degree for cooling is determined with reference to a control map stored in advance in the air conditioning controller 40 based on the outdoor refrigerant pressure Ps detected by the outdoor unit pressure sensor 46b. In this control map, the target supercooling degree for cooling is determined so that the COP of the cycle approaches the maximum value.

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

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

(B) Series Dehumidification Heating Mode In the series dehumidification heating mode, the air conditioning control device 40 sets the first expansion valve 14a to the throttle state, sets the second expansion valve 14b to the throttle state, closes the first on-off valve 15a, and opens the second on-off The valve 15b is closed. Further, the air conditioning control device 40 displaces the air mix door 34 so that the air passages on the heater core 39 and the indoor condenser 12 side are fully opened and the bypass passage 35 side is fully closed.

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

In this cycle configuration, the air conditioning control device 40 controls the operation of the compressor 11 as in the cooling mode.

Further, the air conditioning control device 40 refers to the control map stored in advance in the air conditioning control device 40 based on the target blowing temperature TAO and the like, so that the COP of the cycle approaches the maximum value, and the first expansion valve 14a and The operation of the second expansion valve 14b is controlled. More specifically, the air conditioning controller decreases the throttle opening of the first expansion valve 14a and increases the throttle opening of the second expansion valve 14b as the target blowing temperature TAO increases.

For this reason, in the refrigeration cycle apparatus 10 in the series dehumidifying and heating mode, a refrigeration cycle in which the indoor condenser 12 functions as a radiator and the indoor evaporator 23 functions as an evaporator is configured. Furthermore, when the saturation temperature of the refrigerant in the outdoor heat exchanger 20 is higher than the outdoor temperature Tam, the outdoor heat exchanger 20 functions as a radiator, and the saturation temperature of the refrigerant in the outdoor heat exchanger 20 is higher than the outdoor temperature Tam. If it is lower, the outdoor heat exchanger 20 functions as an evaporator.

And when the saturation temperature of the refrigerant | coolant in the outdoor heat exchanger 20 is higher than the outdoor temperature Tam, the saturation temperature of the refrigerant | coolant of the outdoor heat exchanger 20 is reduced with the raise of the target blowing temperature TAO, and outdoor heat exchange is carried out. The amount of heat released from the refrigerant in the vessel 20 can be reduced. Thereby, the thermal radiation amount of the refrigerant | coolant in the indoor condenser 12 can be increased, and a heating capability can be improved.

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

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

(C) Parallel dehumidifying and heating mode In the parallel dehumidifying and heating mode, the air conditioning control device 40 sets the first expansion valve 14a to the throttle state, sets the second expansion valve 14b to the throttle state, opens the first on-off valve 15a, and opens and closes the second. Open the valve 15b. Further, the air conditioning control device 40 displaces the air mix door 34 so that the air passages on the heater core 39 and the indoor condenser 12 side are fully opened and the bypass passage 35 side is fully closed.

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

In this cycle configuration, the air conditioning control device 40 controls the operation of the compressor 11 as in the cooling mode.

Further, the air conditioning control device 40 refers to the control map stored in advance in the air conditioning control device 40 based on the target blowing temperature TAO and the like, so that the COP of the cycle approaches the maximum value, and the first expansion valve 14a and The operation of the second expansion valve 14b is controlled. More specifically, the air conditioning control device decreases the throttle opening of the first expansion valve 14a as the target blowing temperature TAO increases.

Therefore, in the refrigeration cycle apparatus 10 in the parallel dehumidifying and heating mode, a refrigeration cycle is configured in which the indoor condenser 12 functions as a radiator and the outdoor heat exchanger 20 and the indoor evaporator 23 function as an evaporator. The heat absorbed when the refrigerant evaporates in the outdoor heat exchanger 20 and the indoor evaporator 23 can be radiated to the blown air by the indoor condenser 12. Thereby, the blowing air cooled and dehumidified by the indoor evaporator 23 can be reheated.

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

(D) Heating mode In the heating mode, as described above, the two heating modes of the normal heating mode and the low flow rate heating mode can be switched.

First, in the normal heating mode, the air conditioning control device 40 sets the first expansion valve 14a to the throttle state, sets the second expansion valve 14b to the fully closed state, closes the first on-off valve 15a, and opens the second on-off valve 15b. Further, the air conditioning control device 40 displaces the air mix door 34 so that the air passages on the heater core 39 and the indoor condenser 12 side are fully opened and the bypass passage 35 side is fully closed.

Thereby, in the normal heating mode, as indicated by the thick solid arrow in FIG. 3, the refrigerant flows in the order of the compressor 11 → the indoor condenser 12 → the first expansion valve 14 a → the outdoor heat exchanger 20 → the accumulator 24 → the compressor 11. A circulating vapor compression refrigeration cycle is configured.

In this cycle configuration, the air conditioning controller 40 determines the refrigerant discharge capacity of the compressor 11, that is, the control signal output to the electric motor of the compressor 11. Specifically, the operation of the compressor 11 is controlled so that the pressure of the refrigerant flowing into the indoor condenser 12 becomes the target condensation pressure PDO. The target condensing pressure PDO is determined with reference to a control map stored in advance in the air conditioning control device 40 based on the target blowing temperature TAO.

In this control map, it is determined that the target condensation pressure PDO increases as the target blowing temperature TAO increases.

Further, the air conditioning control device 40 controls the first expansion valve 14a so that the supercooling degree SC of the refrigerant flowing out of the indoor condenser 12 and flowing into the first expansion valve 14a approaches the target supercooling degree SCO for heating. Adjust the throttle opening. The target supercooling degree SCO for heating is determined with reference to a control map stored in advance in the air conditioning control device 40 based on the high-pressure side refrigerant pressure Ph detected by the high-pressure sensor 46a and the blowing mode.

In this control map, the target supercooling degree SCO for heating is determined so that the COP of the cycle approaches the maximum value. Further, in the normal heating mode, as shown in the control characteristic diagram of FIG. 7, the target supercooling degree SCO is not changed even if the blowout mode is changed.

Such control of the opening degree of the first expansion valve 14a is performed in the control step S9 of the main routine of the air conditioning control program described above. Therefore, the control step S9 is a target supercooling degree determination unit that determines the target supercooling degree SCO.

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

Therefore, in the normal heating mode, the vehicle interior can be heated by blowing the blown air heated by the indoor condenser 12 into the vehicle interior. Further, by bringing the supercooling degree SC of the refrigerant flowing out of the indoor condenser 12 close to the target supercooling degree SCO, a high COP can be exhibited in the cycle.

Next, in the low flow rate heating mode, the air conditioning control device 40 brings the first expansion valve 14a into the throttled state. Further, the air conditioning control device 40 controls the operation of the second expansion valve 14b, the first and second on-off valves 15a and 15b, and the electric actuator for the air mix door, as in the normal heating mode. Thereby, in the low flow rate heating mode, as shown by the thick solid line arrow in FIG. 3, a vapor compression refrigeration cycle in which the refrigerant circulates as in the normal heating mode is configured.

In this cycle configuration, the air conditioning control device 40 controls the operation of the compressor 11 as in the normal heating mode.

In addition, the air conditioning control device 40 controls the first expansion valve 14a so that the supercooling degree SC of the refrigerant flowing out of the indoor condenser 12 and flowing into the first expansion valve 14a becomes the heating target supercooling degree SCO. Adjust the throttle opening. The target supercooling degree SCO for heating is determined with reference to a control map stored in advance in the air conditioning control device 40 based on the high-pressure side refrigerant pressure Ph detected by the high-pressure sensor 46a and the blowing mode.

In this control map, as in the normal heating mode, the target supercooling degree SCO for heating is determined so that the COP of the cycle approaches the maximum value. However, as shown in the control characteristic diagram of FIG. While in the mode, the target supercooling degree SCO is reduced.

Also, the air conditioning control device 40 increases the blowing capacity of the blower 32, that is, the control voltage applied to the electric motor of the blower 32. Specifically, a predetermined voltage is applied in advance to the control voltage determined in the same manner as in other operation modes. Moreover, the air-conditioning control apparatus 40 reduces the ventilation capability of the external air fan 20a, ie, the control voltage applied to the electric motor of the external air fan 20a. Specifically, the minimum applied voltage is maintained regardless of the outside temperature Tam.

Other operations are the same as the normal heating mode. Therefore, in the low flow rate heating mode, the vehicle interior can be heated by blowing the blown air heated by the indoor condenser 12 into the vehicle interior.

As described above, according to the vehicle air conditioner 1 of the present embodiment, it is possible to perform cooling, dehumidifying heating, and heating in the passenger compartment.

Here, as in the refrigeration cycle apparatus 10 of the present embodiment, in the normal heating mode, the operation of the first expansion valve 14a is performed so that the supercooling degree SC of the refrigerant flowing out from the indoor condenser 12 approaches the target supercooling degree SCO. If the control is performed, the COP of the cycle can be improved, but a temperature change occurs in the refrigerant flowing through the indoor condenser 12. For this reason, temperature distribution will arise also in the ventilation air heated with the indoor condenser 12. FIG.

Furthermore, if the circulating refrigerant flow rate decreases and the refrigerant is started to be supercooled at the upstream side of the refrigerant flow of the indoor condenser 12, the temperature distribution of the blown air heated by the indoor condenser 12 is generated. The range will expand.

Therefore, when the circulating refrigerant flow rate decreases, the temperature of the blown air heated mainly in the portion upstream of the refrigerant flow from the middle portion in the vertical direction in the heat exchanger of the indoor condenser 12 mainly. The temperature of the blown air heated in the downstream portion of the refrigerant flow with respect to the intermediate portion in the vertical direction may greatly deviate. And such deviation of the temperature of the blown air causes a passenger's comfortable feeling of heating to be impaired.

In contrast, in the refrigeration cycle apparatus 10 of the present embodiment, when it is determined that the low-flow-rate operation is performed when heating the passenger compartment, the low-flow-rate heating mode is entered, and the target subcooling degree is achieved. Reduce SCO. Therefore, it is possible to prevent the refrigerant from being supercooled at the upstream side of the refrigerant flow in the indoor condenser 12.

As a result, the expansion of the range in which the temperature distribution of the blown air heated by the indoor condenser 12 occurs can be suppressed even during the low flow operation. Furthermore, when it is not determined that the low-flow operation is being performed, the target supercooling degree SCO is determined so that the COP approaches the maximum value, so that the refrigeration cycle apparatus 10 can exhibit a high COP. it can.

Further, in the refrigeration cycle apparatus 10 of the present embodiment, the target supercooling degree SCO is lowered when the blowing mode is the foot mode. According to this, it is possible to prevent the COP from being lowered by unnecessarily lowering the target supercooling degree SCO.

To explain this in more detail, in the foot mode, the blown air heated mainly at the downstream portion of the refrigerant flow from the intermediate portion in the vertical direction in the heat exchanger of the indoor condenser 12 is the foot opening. It blows out toward the passenger | crew's step through the hole 37a. As described above, in the heat exchanger of the indoor condenser 12, the temperature of the blown air heated mainly at the downstream side of the refrigerant flow with respect to the vertical intermediate portion is likely to increase in temperature during low flow operation.

On the other hand, in the heat exchange part of the indoor condenser 12, the temperature of the blown air heated mainly at the upstream side of the refrigerant flow with respect to the intermediate part in the vertical direction is lowered even during low flow operation. Is small. Therefore, even during low-flow operation, when the face mode (that is, the first blowing mode) is in effect, the passenger's heating is more effective than when the foot mode (that is, the second blowing mode) is set. It is difficult to worsen the feeling.

Therefore, the COP is unnecessarily reduced in the low-flow-rate heating mode by reducing the target supercooling degree SCO during the low-flow-rate operation and the foot mode in which the passenger's feeling of heating tends to deteriorate. Can be suppressed.

Further, in the refrigeration cycle apparatus 10 of the present embodiment, the blowing capacity of the blower 32 is increased in the low flow rate heating mode. Since the refrigerant | coolant condensing pressure in the indoor condenser 12 falls according to this, with the increase in the ventilation capability of the air blower 32, an air-conditioning control apparatus is used so that the pressure of the refrigerant | coolant which flows in into the indoor condenser 12 may become the target condensing pressure PDO. 40 increases the refrigerant discharge capacity (that is, the rotational speed) of the compressor 11.

As a result, the range in which the temperature distribution of the blown air heated by the indoor condenser 12 occurs can be effectively reduced.

Moreover, in the refrigeration cycle apparatus 10 of the present embodiment, the air blowing capacity of the outside air fan 20a is reduced during the low flow rate heating mode. According to this, since the refrigerant | coolant evaporation pressure in the outdoor heat exchanger 20 falls by the reduction | decrease in the ventilation capability of the outdoor air fan 20a, the refrigerant | coolant condensing pressure in the indoor condenser 12 also falls. Therefore, the air conditioning controller 40 increases the refrigerant discharge capacity (that is, the rotation speed) of the compressor 11 so that the pressure of the refrigerant flowing into the indoor condenser 12 becomes the target condensation pressure PDO.

As a result, the range in which the temperature distribution of the blown air heated by the indoor condenser 12 occurs can be effectively reduced.

(Other embodiments)
The present disclosure is not limited to the above-described embodiment, and can be variously modified as follows without departing from the spirit of the present disclosure.

(1) In the above-described embodiment, an example in which the refrigeration cycle apparatus 10 according to the present disclosure is applied to a vehicle air conditioner for a hybrid vehicle has been described, but application of the refrigeration cycle apparatus 10 is not limited thereto. Of course, the present invention may be applied to a normal engine vehicle that obtains driving force for driving a vehicle from an engine, a vehicle air conditioner for an electric vehicle that obtains driving force for driving a vehicle from an electric motor for traveling, or a stationary type You may apply to an air conditioner.

(2) In the above-described embodiment, when the control steps S41 to S43 are employed as the low flow rate operation determination unit and all the conditions of the control steps S41 to S43 are satisfied (when the determination is Yes), The example in which it is determined that the low flow operation is performed has been described, but the low flow operation determination unit is not limited to this. For example, when at least one of the control steps S41 to S43 is satisfied, it may be determined that the low flow operation is being performed.

(3) In the above-described embodiment, the example in which the target supercooling degree SCO is reduced when it is determined that the low-flow operation is performed and the blowing mode is the foot mode has been described. When it is determined that the flow rate operation is performed, the target supercooling degree SCO may be decreased regardless of the blowout mode. The reason is that the distribution mode of the temperature of the blown air varies depending on the path configuration of the indoor condenser 12 and the like.

(4) In the above-described embodiment, the example in which the blowing capacity of the outside air fan 20a is reduced when it is determined that the low flow operation is performed has been described. However, the outside air flowing into the outdoor heat exchanger 20 has been described. A similar effect can be obtained by reducing the flow rate. Therefore, a shutter device (for example, a grill shutter) may be disposed in a ventilation path that guides outside air to the outdoor heat exchanger 20, and the ventilation path may be blocked by the shutter in the low flow rate heating mode.

(5) The refrigeration cycle apparatus 10 is not limited to the one disclosed in the above embodiment. For example, the refrigeration cycle apparatus may constitute a gas injection cycle in the heating mode (that is, the normal heating mode and the low flow rate heating mode).

In this case, the compressor 11 has a two-stage booster having a suction port for sucking refrigerant, a discharge port for discharging compressed refrigerant, and an intermediate pressure port for joining the intermediate pressure refrigerant generated in the cycle with the refrigerant in the compression process. A formula type may be adopted.

Furthermore, a gas-liquid separation unit for separating the gas-liquid of the intermediate pressure refrigerant decompressed by the first expansion valve 14a is provided. A refrigerant circuit switching device is connected to a refrigerant passage connecting the gas-phase refrigerant outlet side of the gas-liquid separator and the intermediate pressure port side of the compressor, and connecting the gas-phase refrigerant outlet side and the intermediate pressure port side of the compressor. An on-off valve similar to the above-described embodiment is arranged.

The gas-liquid separator is connected to a refrigerant passage connecting the liquid-phase refrigerant outlet side of the gas-liquid separator and the inlet side of the outdoor heat exchanger 20 and connecting the liquid-phase refrigerant outlet side and the inlet side of the outdoor heat exchanger 20. An expansion valve similar to that of the above-described embodiment may be disposed as a decompression device that decompresses the liquid-phase refrigerant that has flowed out of the refrigerant until it becomes a low-pressure refrigerant.

In the above-described embodiment, the refrigeration cycle apparatus 10 configured to be able to switch the refrigerant circuit has been described, but switching of the refrigerant circuit is not essential. If it is a refrigeration cycle apparatus that can be operated at least in the heating mode, it is possible to obtain an effect of reducing the range in which the temperature distribution of the blown air described above occurs.

Moreover, although the above-mentioned embodiment demonstrated the example which employ | adopted R134a as a refrigerant | coolant of the refrigerating-cycle apparatus 10, a refrigerant | coolant is not limited to this. For example, R1234yf, R600a, R410A, R404A, R32, R407C, etc. may be adopted. Or you may employ | adopt the mixed refrigerant | coolant etc. which mixed multiple types among these refrigerant | coolants.

Claims (7)

1. A refrigeration cycle apparatus applied to an air conditioner,
   A compressor (11) for compressing and discharging the refrigerant;
   A heat exchanger (12) for heating that heat-exchanges the high-pressure refrigerant discharged from the compressor and the blown air blown into the air-conditioning target space, and heats the blown air;
   A decompression device (14a) for decompressing the refrigerant flowing out of the heating heat exchanger;
   An outdoor heat exchanger (20) for exchanging heat between the low-pressure refrigerant decompressed by the decompression device and the outside air;
   A decompression device controller (40b) for controlling the operation of the decompression device;
   A target supercooling degree determination unit (S9) for determining a target supercooling degree (SCO) of the refrigerant flowing out of the heating heat exchanger;
   A low flow rate operation determination unit (S41 to S43) for determining that the flow rate of the refrigerant circulating through the cycle is a low flow rate operation in which the flow rate is lower than a predetermined reference flow rate,
   The decompression device control unit controls the operation of the decompression device so that the refrigerant flowing out of the heat exchanger for heating approaches the target supercooling degree (SCO),
   The target supercooling degree determination unit is a refrigeration cycle apparatus that reduces the target supercooling degree (SCO) when the low flow rate operation determination unit determines that the low flow rate operation is performed.
2. The low flow rate operation determination unit (S41) is configured to determine that the low flow rate operation is performed when an outside air temperature (Tam) is equal to or higher than a predetermined reference outside air temperature (KTam). The refrigeration cycle apparatus according to 1.
3. The low flow rate operation determination unit (S42) performs the low flow rate operation when the inflow air temperature (TAin) of the blown air flowing into the heating heat exchanger becomes equal to or higher than a predetermined reference inflow temperature (KTAin). The refrigeration cycle apparatus according to claim 1 or 2, wherein it is determined that
4. The low flow rate operation determination unit (S43) determines that the low flow rate operation is in effect when the refrigerant discharge capacity of the compressor 11 is equal to or lower than a predetermined reference discharge capacity. The refrigeration cycle apparatus according to any one of 1 to 3.
5. An outside air fan (20a) for blowing outside air to the outdoor heat exchanger;
   An outside air fan control unit (40d) for controlling the blowing capacity of the outside air fan,
   The said outside air fan control part reduces the ventilation capacity of the said outside air fan, when the said low flow operation determination part determines that it is the said low flow operation. The refrigeration cycle apparatus described in 1.
6. A refrigeration cycle apparatus applied to a vehicle air conditioner,
   Among the heat exchange parts of the heat exchanger for heating, the first blow mode for blowing blown air heated at the part upstream of the refrigerant flow from the intermediate part and the middle of the heat exchange parts of the heat exchanger for heating. A blowing mode switching device (38a to 38c) for switching between a second blowing mode for blowing out the blown air heated at a site downstream of the refrigerant flow from the unit,
   The target supercooling degree determination unit determines that the low flow rate operation determination unit is in the low flow rate operation, and the target mode is determined when the blow mode switching device is switched to the second blow mode. The refrigeration cycle apparatus according to any one of claims 1 to 5, wherein the refrigeration cycle apparatus reduces the degree of supercooling (SCO).
7. A blower (32) for blowing air to the heat exchanger for heating;
   A blower control unit (40e) for controlling the blowing capacity of the blower,
   The blower control unit increases the blowing capacity of the blower when the low flow rate operation determination unit determines that the low flow rate operation is performed. The refrigeration cycle apparatus described.
   
   

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