JP2012148600A - Vehicle air conditioning device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vehicle air conditioning device that operates with high efficiency upon a heating operation.SOLUTION: The air conditioner includes: an HVAC unit (2); a heat pump cycle (4); a refrigerant flow-rate range setting device for setting a refrigerant flow-rate range where a refrigerant temperature is less than the air temperature and a refrigerant flow rate is equal to or less than an allowable refrigerant flow rate, on the basis of the allowable refrigerant flow rate detected by an allowable refrigerant flow-rate estimating device; and a refrigerant flow-rate controller (63) for controlling the refrigerant flow rate within the refrigerant flow-rate range set by the refrigerant flow-rate range setting device, when an inlet refrigerant state value detected by an inlet refrigerant state-value detector (62) is equal to or more than an air refrigerant state value detected by an air refrigerant state-value detector (58).

Description

  The present invention relates to a vehicle air conditioner, for example, a vehicle air conditioner provided with a heat pump cycle for an electric vehicle.

As this type of vehicle air conditioner, for example, there is an air conditioner equipped with a heat pump cycle for an electric vehicle, and an apparatus that performs a cooling / heating operation and a dehumidifying operation by switching the heat pump cycle is disclosed (for example, see Patent Document 1). .
In the heat pump cycle, the refrigerant pipe is sequentially provided with a first expansion valve, a first heat exchanger, a compressor, a second heat exchanger, a second expansion valve, and an outdoor heat exchanger that exchanges heat between the refrigerant and the outside air. The first bypass passage that bypasses the first expansion valve and the first heat exchanger during the heating operation and the second bypass passage that bypasses the second expansion valve during the cooling operation are connected to the refrigerant flow path. Configuration is conceivable.

Japanese Patent No. 3321907

  In the heat pump cycle, the outdoor heat exchanger is used as a condenser that radiates heat from the refrigerant to the outside air during the cooling operation, and is used as an evaporator that absorbs heat from the outside air to the refrigerant during the heating operation. However, when the outdoor heat exchanger is used as a condenser and when it is used as an evaporator, the refrigerant state in the outdoor heat exchanger is different, so the refrigerant pressure at the inlet side and the outlet side of the outdoor heat exchanger is different. The loss will vary greatly.

Specifically, if priority is given to the function of the outdoor heat exchanger as a condenser in order to ensure the cooling performance of the air conditioner, the pressure loss in the outdoor heat exchanger that functions as an evaporator increases during heating operation. There arises a problem that the efficiency of the air conditioner is significantly reduced.
Therefore, an electric heater as described in the above prior art is separately provided to assist the function of the evaporator in the outdoor heat exchanger during heating operation.

However, if an electric heater is provided in an electric vehicle, the power consumption of the vehicle increases and the cruising distance of the vehicle may be shortened.
In addition, it is not uncommon for the outside air temperature during the heating operation in winter to be 0 ° C. or lower, but in order to absorb heat from the outside air, it is necessary to lower the refrigerant temperature in the outdoor heat exchanger to below the outside air temperature. In such a case, since the heat load in the passenger compartment increases, a large amount of heat is required during the heating operation, and it is necessary to increase the refrigerant flow rate circulated in the heat pump cycle.

Further, when the outside air temperature is low, particularly when a chlorofluorocarbon refrigerant is used as the refrigerant, the saturated vapor pressure of the refrigerant at the outside air temperature may be reduced to an atmospheric pressure or a negative pressure. When the refrigerant pressure becomes atmospheric pressure or negative pressure, external air, moisture, dust, or the like may enter the refrigerant piping of the heat pump cycle. Therefore, the apparatus is generally operated at a refrigerant pressure higher than atmospheric pressure.
However, when the heat pump cycle is controlled and operated so that the outlet refrigerant pressure on the outlet side of the outdoor heat exchanger becomes larger than the atmospheric pressure while increasing the refrigerant flow rate circulated in the heat pump cycle during the heating operation, the outdoor heat exchanger The saturation temperature corresponding to the inlet refrigerant pressure on the inlet side of the refrigerant becomes higher than the outside air temperature, heat is released from the refrigerant to the outside air on the inlet side of the outdoor heat exchanger, and evaporation increases due to an increase in the amount of refrigerant circulation. There arises a problem that the efficiency of the outdoor heat exchanger as a heat exchanger is significantly reduced.

  The present invention has been made in view of the above points, and an object of the present invention is to provide a vehicle air conditioner that can realize high-efficiency operation during heating operation.

  In order to achieve the above object, an air conditioner for a vehicle according to claim 1 of the present invention includes an HVAC unit that blows out temperature-adjusted air into a vehicle compartment by a heat exchanger disposed in an air flow path. A heat pump cycle in which a refrigerant, a heat exchanger, an expansion valve, and an outdoor heat exchanger for exchanging heat between the refrigerant and the outside air are sequentially inserted in the refrigerant flow path; an outside air temperature detecting means for detecting the outside air temperature; An inlet refrigerant state detecting means for detecting an inlet refrigerant state value on the inlet side of the heat exchanger, and an outside air refrigerant state detecting means for detecting an outside air refrigerant state value in the outside air based on the outside air temperature detected by the outside air temperature detecting means; Allowable pressure loss estimating means for estimating allowable pressure loss in the outdoor heat exchanger at the outside air temperature detected by the outside air temperature detecting means, and the outdoor heat exchanger based on the allowable pressure loss estimated by the allowable pressure loss estimating means The refrigerant temperature is less than the outside air temperature based on the allowable refrigerant flow rate estimating means for estimating the flowing allowable refrigerant flow rate, the outside air temperature detected by the outside air temperature detecting means, and the allowable refrigerant flow rate detected by the allowable refrigerant flow rate estimating means, and the refrigerant A refrigerant flow rate range setting unit that sets a refrigerant flow rate range in which the flow rate is equal to or lower than an allowable refrigerant flow rate, and an inlet refrigerant state value detected by the inlet refrigerant state detection unit is greater than or equal to an outdoor refrigerant state value detected by the outdoor refrigerant state detection unit When it becomes, it is provided with the refrigerant | coolant flow control means which controls a refrigerant | coolant flow within the refrigerant | coolant flow range set by the refrigerant | coolant flow range setting means.

  According to the second aspect of the present invention, the inlet refrigerant state detecting means detects the inlet refrigerant temperature on the inlet side of the outdoor heat exchanger as the inlet refrigerant state value, and the outside air refrigerant state detecting means detects the outside air temperature as the outside refrigerant state value. An outside air temperature detected by the means is detected, and the refrigerant flow rate control means controls the refrigerant flow rate within a refrigerant flow rate control range when the inlet refrigerant temperature is equal to or higher than the outside air temperature.

  According to a third aspect of the present invention, the inlet refrigerant state detecting means detects the inlet refrigerant pressure on the inlet side of the outdoor heat exchanger as the inlet refrigerant state value, and the outside air refrigerant state detecting means detects the outside air temperature as the outside refrigerant state value. The refrigerant saturated vapor pressure at the outside air temperature detected by the means is detected, and the refrigerant flow control means controls the refrigerant flow rate within the refrigerant flow control range when the inlet refrigerant pressure is equal to or higher than the saturated vapor pressure. Yes.

  The invention according to claim 4 is based on the suction refrigerant state detection means for detecting the suction refrigerant temperature and the suction refrigerant pressure on the suction side of the compressor, and the suction refrigerant temperature and the suction refrigerant pressure detected by the suction refrigerant state detection means. Intake refrigerant density estimation means for estimating the intake refrigerant density on the suction side of the compressor, rotation speed detection means for detecting the rotation speed of the compressor, intake refrigerant density and rotation speed detection means detected by the intake refrigerant state detection means The refrigerant flow rate estimating means for estimating the refrigerant flow rate circulating through the refrigerant flow path based on the number of revolutions detected in the step, and the refrigerant pressure loss in the outdoor heat exchanger based on the refrigerant flow rate estimated by the refrigerant flow rate estimating means The outlet refrigerant pressure at the outlet side of the outdoor heat exchanger based on the refrigerant pressure loss estimation means, the outside air temperature detected by the outside air temperature detection means, and the refrigerant flow rate estimated by the refrigerant flow rate estimation means The outlet refrigerant pressure detecting means for detecting and the inlet refrigerant state detecting means are the inlet refrigerant whose sum of the refrigerant pressure loss estimated by the refrigerant pressure loss estimating means and the outlet refrigerant pressure detected by the outlet refrigerant pressure detecting means is estimated. It is characterized by detecting as pressure.

The invention according to claim 5 includes an intake refrigerant pressure detecting means for detecting an intake refrigerant pressure on the intake side of the compressor, and the refrigerant flow rate control means is configured such that the intake refrigerant pressure detected by the intake refrigerant pressure detecting means is greater than the atmospheric pressure. The refrigerant flow rate is controlled to be large.
The invention according to claim 6 is characterized in that the refrigerant flow rate control means performs expansion valve opening degree control for controlling the refrigerant flow rate by controlling the opening degree of the expansion valve.

  The invention according to claim 7 is characterized in that the refrigerant flow rate control means performs compressor discharge capacity control for controlling the refrigerant flow rate by controlling the discharge capacity of the compressor.

  According to the vehicle air conditioner of the first aspect, when the inlet refrigerant state value of the outdoor heat exchanger is equal to or greater than the outside air refrigerant state value detected by the outside air refrigerant state detecting means, the refrigerant flow rate range setting means is set. Refrigerant flow rate control means for controlling the refrigerant flow rate within the refrigerant flow rate range is provided. As a result, during the heating operation of the vehicle air conditioner, it becomes possible to operate the heat pump cycle within the refrigerant flow rate range in which the refrigerant temperature is always lower than the outside air temperature and the refrigerant flow rate is equal to or lower than the allowable refrigerant flow rate. Even during operation, pressure loss in the outdoor heat exchanger can be reduced, and high efficiency operation of the vehicle air conditioner during heating operation can be realized.

More specifically, the refrigerant flow rate control means controls the refrigerant flow rate within the refrigerant flow rate control range when the inlet refrigerant temperature is equal to or higher than the outside air temperature.
Specifically, when the inlet refrigerant pressure is equal to or higher than the saturated vapor pressure, the refrigerant flow rate is controlled within the refrigerant flow rate control range.

  According to the fourth aspect of the present invention, the inlet refrigerant state detecting means is configured to estimate the sum of the refrigerant pressure loss estimated by the refrigerant pressure loss estimating means and the outlet refrigerant pressure detected by the outlet refrigerant pressure detecting means. By detecting the refrigerant pressure, it is possible to determine whether or not the refrigerant flow control by the refrigerant flow control means is necessary without providing a sensor for detecting the inlet refrigerant state. High efficiency operation of the device can be realized.

  According to the fifth aspect of the present invention, the refrigerant flow rate control means controls the refrigerant flow rate so that the suction refrigerant pressure detected by the suction refrigerant pressure detection means is greater than the atmospheric pressure, so that the negative pressure of the heat pump cycle is reached. Since it is possible to prevent operation, it is possible to reliably prevent the entry of air, moisture, dust, etc. into the refrigerant flow path of the heat pump cycle, and to ensure high-efficiency operation of the vehicle air conditioner. it can.

Specifically, the refrigerant flow rate control means performs expansion valve opening degree control for controlling the refrigerant flow rate by controlling the opening degree of the expansion valve.
Specifically, the refrigerant flow rate control means performs compressor discharge capacity control for controlling the refrigerant flow rate by controlling the discharge capacity of the compressor.

It is the block diagram which showed the state at the time of the heating operation of the vehicle air conditioner which concerns on 1st Embodiment of this invention. It is the block diagram which showed the state at the time of air_conditionaing | cooling operation of the vehicle air conditioner of FIG. It is a flowchart which shows the control routine of the refrigerant | coolant flow control performed in the control unit of FIG. It is the figure which showed the relationship between outside temperature and the allowable pressure loss in an outdoor heat exchanger. It is the figure which showed the relationship between the allowable refrigerant | coolant flow volume and allowable pressure loss in an outdoor heat exchanger. It is the figure which showed the relationship between the refrigerant | coolant flow volume in an outdoor heat exchanger, and an inlet refrigerant temperature. It is the block diagram which showed the state at the time of the heating operation of the vehicle air conditioner which concerns on 2nd Embodiment of this invention. It is the block diagram which showed the state at the time of air_conditionaing | cooling operation of the vehicle air conditioner of FIG. It is a flowchart which shows the control routine of the refrigerant | coolant flow control performed in the control unit of FIG.

[First embodiment]
A vehicle air conditioner 1 according to a first embodiment of the present invention will be described below with reference to FIGS.
FIG. 1 is a configuration diagram illustrating a state of the vehicle air conditioner 1 during a heating operation, and FIG. 2 is a configuration diagram illustrating a state of the vehicle air conditioner 1 during a cooling operation.
The vehicle air conditioner 1 is disposed, for example, in a vehicle interior of an electric vehicle, takes in vehicle interior air (inside air) or vehicle exterior air (outside air), regulates the temperature, and blows it out into the vehicle interior (Heating Ventilation and Air). (Conditioning Unit) 2 and a heat pump cycle 4 that is disposed outside the passenger compartment and exchanges heat with the HVAC unit 2 via a chlorofluorocarbon refrigerant, and is disposed outside the passenger compartment and cools the electric motor 6 for driving the vehicle. And a cooling circuit 8.

  The HVAC unit 2 is formed on the upstream side of the air flow path 10 with the housing 12 forming the air flow path 10, and the internal air intake port 14 that takes in the internal air into the housing 12 and the external air intake port that takes in the external air into the housing 12. 16, an inside / outside air switching damper 18 that opens and closes the intake ports 14, 16, a blower 20 that is connected to the upstream side of the air flow path 10 and blows in the taken inside air or outside air, and a blowing direction in the air flow path 10. The first heat exchanger 22, the air mix damper 24, the second heat exchanger (heat exchanger) 26, and the first heat exchanger 22, A differential air outlet 28, a face air outlet 30, and a foot air outlet that blow out the temperature-controlled air by the air mix damper 24 and the second heat exchanger 26 into the vehicle interior. 2, DEF damper 34 for opening and closing the outlet 28, 30, 32, respectively, and a face damper 36, and foot damper 38.

  The heat pump cycle 4 includes a first expansion valve 42 for adiabatically expanding the refrigerant in a refrigerant pipe (refrigerant flow path) 40 through which, for example, R1234yf, which is a fluorocarbon refrigerant, circulates, and the first heat exchanger provided in the HVAC unit 2. 22, an electric compressor (compressor) 44 for compressing the refrigerant, the second heat exchanger 26 provided in the HVAC unit 2, a second expansion valve (expansion valve) 46 for adiabatically expanding the refrigerant, and the outside of the passenger compartment It is configured by a closed cycle refrigerant circuit in which an outdoor heat exchanger 48 that receives the traveling wind of the vehicle from the front of the vehicle and exchanges heat between the refrigerant and the outside air is sequentially inserted. Connected to the refrigerant pipe 40 are a first bypass pipe 50 that bypasses the first expansion valve 42 and the first heat exchanger 22 during heating operation, and a second bypass pipe 52 that bypasses the second expansion valve 46 during cooling operation. Has been. A first solenoid valve 54 and a second solenoid valve 56 are inserted in the first bypass pipe 50 and the second bypass pipe 52, respectively.

  Outside the passenger compartment, an outside air temperature sensor (outside air temperature detection means, outside air refrigerant state detection means) 58 for detecting the outside air temperature is provided, and the outdoor heat exchanger 48 is connected to the refrigerant pipe 40 on the inlet side of the outdoor heat exchanger 48. An inlet refrigerant temperature sensor (inlet refrigerant state detection means) 60 for detecting the inlet refrigerant temperature (inlet refrigerant state value) of the compressor 44 is provided, and the refrigerant pipe 40 on the suction side of the compressor 44 is supplied with the intake refrigerant pressure of the compressor 44. An intake refrigerant pressure sensor (intake refrigerant pressure detection means) 62 for detection is provided. The electromagnetic valves 54 and 56, the expansion valves 42 and 46, the sensors 58, 60 and 62, and the compressor 44 are electrically connected to a control unit (refrigerant flow control means) 63.

On the other hand, the cooling water circuit 8 is configured by a closed cycle circuit in which a radiator 66 for cooling the motor 6 is inserted in a cooling water pipe 64 through which the cooling water circulates, and includes a fan 68 for sending air to the radiator 66. .
Below, operation | movement of the vehicle air conditioner 1 which has said structure is demonstrated.

(During normal heating operation)
In the heating operation shown in FIG. 1, the first electromagnetic valve 54 is opened, the first expansion valve 42 and the first heat exchanger 22 are bypassed, the second electromagnetic valve 56 is closed, and the refrigerant passes through the refrigerant pipe 40. Circulation is performed as indicated by the solid line arrows in FIG. 1, and the heat pump cycle 4 is operated as a heat pump. On the other hand, in the HVAC unit 2, heat exchange between the refrigerant and air is not performed here because the first heat exchanger 22 is bypassed, but the air flow path is opened because the air mix damper 24 is opened. 10, air flows into the second heat exchanger 26 as indicated by an arrow, and the second heat exchanger 26 performs heat exchange between the refrigerant and the air.

  In the heat pump cycle 4, first, the high-temperature and high-pressure gas refrigerant compressed by the compressor 44 flows into the second heat exchanger 26, and exchanges heat with air taken into the air flow path 10 from the intake ports 14 and 16. It is cooled and condensed. At this time, the air heated in the 2nd heat exchanger 26 blows off from each blower outlet 28,30,32, and uses for the heating of a vehicle interior.

  The refrigerant condensed in the second heat exchanger 26 is adiabatically expanded and depressurized by the second expansion valve 46, and then becomes a gas-liquid two-phase refrigerant and flows into the outdoor heat exchanger 48. In the outdoor heat exchanger 48, the gas-liquid two-phase refrigerant absorbs heat from the outside air blown by the fan 68 and / or the outside air received by the running wind of the vehicle, and is evaporated and gasified. Then, it is sucked into the compressor 44 and compressed again.

(During cooling operation)
In the cooling operation shown in FIG. 2, the first solenoid valve 54 is closed, the second solenoid valve 56 is opened, the second expansion valve 46 is bypassed, and the refrigerant is shown by the solid line arrow in FIG. Circulate like On the other hand, in the HVAC unit 2, since the air mix damper 24 is closed, the air flow path 10 prevents air from flowing into the second heat exchanger 26 as indicated by the arrows, and the second heat exchanger 26. Heat exchange between the refrigerant flowing through and the air flowing through the air flow path 10 is not performed. Further, since the first electromagnetic valve 54 is closed, air flows into the first heat exchanger 22 as indicated by arrows in the air flow path 10, and the refrigerant and air flowing through the first heat exchanger 22. Heat exchange with the air flowing through the flow path 10 is performed.

  In the heat pump cycle 4, the high-temperature and high-pressure gas refrigerant first compressed by the compressor 44 flows into the second heat exchanger 26, but heat exchange with the air is not performed due to the closing of the air mix damper 24, and the second electromagnetic as it is Just passing through the valve 56 flows into the outdoor heat exchanger 48. The high-temperature and high-pressure gas refrigerant dissipates heat to the outside air, flows into the first expansion valve 42, undergoes adiabatic expansion and pressure reduction, and then flows into the first heat exchanger 22. The refrigerant flowing into the first heat exchanger 22 is heated and vaporized into gas by heat exchange with the air taken into the air flow path 10 from the intake ports 14 and 16. At this time, the air cooled in the first heat exchanger 22 is blown out from the respective outlets 28, 30, and 32, and is provided for cooling in the passenger compartment. Then, the refrigerant that has passed through the first heat exchanger 22 is sucked into the compressor 44 and compressed again.

(During heating operation where the outside air temperature is 0 ° C or less)
In this case, refrigerant flow control (refrigerant flow control means) for controlling the refrigerant flow rate within a predetermined refrigerant flow control range A is performed.
Hereinafter, the control routine of the refrigerant flow rate control executed in the control unit 63 will be described with reference to the flowchart of FIG.
First, when this control is started, the process proceeds to S1 (S represents a step, the same shall apply hereinafter). In S1, the sensor values of the sensors 58, 60, 62 are read, and the process proceeds to S2.

  In S2, it is determined whether or not the inlet refrigerant temperature Tei detected by the inlet refrigerant temperature sensor 60 is equal to or higher than the outside air temperature To detected by the outside air temperature sensor, and the determination result is (No) and the inlet refrigerant temperature Tei is outside air. When it is determined that the temperature is not equal to or higher than the outside air temperature To detected by the temperature sensor, the process returns to S1 and the normal heating operation is performed. On the other hand, when the determination result is (Yes) and it is determined that the inlet refrigerant temperature Tei is equal to or higher than the outside air temperature To detected by the outside air temperature sensor, the process proceeds to S3.

In S3, the target intake refrigerant pressure Pcst is set to be larger than 0 MPaG so that the intake refrigerant pressure Pcs detected by the intake refrigerant pressure sensor 62 becomes larger than the atmospheric pressure, the compressor 44 is controlled, and the process proceeds to S4.
In S4, the expansion valve opening control for controlling the opening of the second expansion valve 46 and / or the compressor discharge capacity control for controlling the discharge capacity of the compressor 44 are performed, and the suction refrigerant pressure Pcs> 0 MPaG and After the refrigerant flow rate is controlled so that the refrigerant flow rate F is controlled within a predetermined refrigerant flow rate range A, the process returns to S1 again, and thereafter, steps S1 to S4 are repeatedly executed at a predetermined cycle.

  Here, the refrigerant flow rate range A is determined with reference to the maps based on FIGS. 4 to 6 stored in the control unit 63. FIG. 4 shows the relationship between the outdoor temperature To detected by the outdoor temperature sensor 58 and the allowable pressure loss ΔPea in the outdoor heat exchanger 48, and FIG. 5 shows the allowable refrigerant flow rate Fea and the allowable pressure loss in the outdoor heat exchanger 48. FIG. 6 shows the relationship between the refrigerant flow rate F and the inlet refrigerant temperature Tei in the outdoor heat exchanger 48.

  First, in FIG. 4, the allowable pressure loss ΔPea in the outdoor heat exchanger 48 at the outdoor temperature To detected by the outdoor temperature sensor 58 is estimated (allowable pressure loss estimation means). Next, in FIG. 5, the allowable refrigerant flow rate Fea of the refrigerant flowing through the outdoor heat exchanger 48 is estimated based on the allowable pressure loss ΔPea estimated in FIG. 4 (allowable refrigerant flow rate estimating means). Next, in FIG. 6, the inlet refrigerant temperature Tei is less than the outside air temperature To and the refrigerant flow rate F is allowed based on the outside air temperature To detected by the outside air temperature sensor 58 and the allowable refrigerant flow rate Fea estimated in FIG. A refrigerant flow rate range A that is equal to or lower than the refrigerant flow rate Fea is set (refrigerant flow rate range setting means). And the said refrigerant | coolant flow control is performed in the refrigerant | coolant flow range A set in this way.

  As described above, in the present embodiment, even if the heat exchanger is designed to function as a condenser by performing the above refrigerant flow rate control, the inlet refrigerant temperature Tei during the heating operation of the vehicle air conditioner. Is less than the outside air temperature To and the heat pump cycle 4 can be operated within the refrigerant flow rate range A in which the refrigerant flow rate F is equal to or less than the allowable refrigerant flow rate Fea. Therefore, the outdoor heat exchanger 48 even during heating operation. The pressure loss ΔPe at can be reduced, and high efficiency operation of the vehicle air conditioner 1 during heating operation can be realized.

  In the refrigerant flow rate control, in S4, the target intake refrigerant pressure Pcst is set to be greater than 0 MPaG so that the intake refrigerant pressure Pcs detected by the intake refrigerant pressure sensor 62 is greater than the atmospheric pressure, and the compressor 44 is activated. By controlling, negative pressure operation of the heat pump cycle 4 can be prevented, so that intrusion of air, moisture, dust and the like into the refrigerant pipe 40 of the heat pump cycle 4 can be surely prevented, and vehicle air conditioning The highly efficient operation of the device 1 can be realized with certainty.

[Second Embodiment]
A vehicle air conditioner 70 according to a second embodiment of the present invention will be described below with reference to FIGS.
FIG. 7 is a diagram showing a configuration during heating operation of the vehicle air conditioner 70, and FIG. 8 is a diagram showing a configuration during cooling operation of the vehicle air conditioner 70.

  The vehicle air conditioner 70 does not include the inlet refrigerant temperature sensor 60 of the first embodiment, and the intake refrigerant pressure sensor 62 of the first embodiment detects the refrigerant pressure and refrigerant temperature on the intake side of the compressor 44. It is changed to a possible intake refrigerant temperature / pressure sensor (intake refrigerant state detection means) 72, and further includes a rotation speed sensor (revolution speed detection means) 74 for detecting the rotation speed Nc of the compressor 44. The other components similar to those of the first embodiment are denoted by the same reference numerals and description thereof is omitted.

(During heating operation where the outside air temperature is 0 ° C or less)
In this case, similarly to the case of the first embodiment, refrigerant flow control (refrigerant flow control means) for controlling the refrigerant flow rate in the refrigerant flow control range A is performed.
Hereinafter, the control routine of the refrigerant flow rate control of the second embodiment executed in the control unit 63 will be described with reference to the flowchart of FIG. 9.
First, when this control is started, the process proceeds to S11. In S11, the sensor values of the sensors 58 and 72 are read, and the process proceeds to S12.

In S12, after calculating the intake refrigerant density Dcs on the intake side of the compressor 44 based on the intake refrigerant temperature Tcs and the intake refrigerant pressure Pcs detected by the intake refrigerant temperature and pressure sensor 72 (intake refrigerant density estimating means), The process proceeds to S13.
In S13, after the rotation speed sensor 74 measures the rotation speed Nc of the compressor 44, the process proceeds to S14.

In S14, after calculating the refrigerant flow rate F circulating through the refrigerant piping based on the suction refrigerant density Dcs calculated in S12 and the rotation speed Nc measured in S13 (refrigerant flow rate estimating means), the process proceeds to S15.
In S15, referring to the map based on FIG. 5, after estimating the refrigerant pressure loss ΔPe in the outdoor heat exchanger 48 based on the refrigerant flow rate F estimated in S14 (refrigerant pressure loss estimating means), the process proceeds to S16.

  In S16, referring to the map based on FIG. 6, the outside air temperature To read in S11, the refrigerant flow rate F estimated in S14, and the outlet refrigerant pressure Pee on the outlet side of the outdoor heat exchanger 48 are obtained by the intake refrigerant pressure sensor 72. The detected pressure value is regarded as the same value (outlet refrigerant pressure detecting means), and the sum of the refrigerant pressure loss ΔPee estimated in S15 and the pressure value detected by the intake refrigerant pressure sensor 72 is estimated as the inlet refrigerant pressure Pei ( Inlet refrigerant state detection means).

  And the refrigerant | coolant saturated vapor pressure Po of the refrigerant | coolant in the outside temperature To read by S12 is calculated by calculation, it is determined whether the inlet refrigerant pressure Pei is more than the refrigerant | coolant saturated vapor pressure Po, and the determination result is (No) If it is determined that the inlet refrigerant pressure Pei is not equal to or higher than the refrigerant saturated vapor pressure Po, the process returns to S11. Shifts to S17.

In S17, the target intake refrigerant pressure Pcst is set to be greater than 0 MPaG so that the intake refrigerant pressure Pcs detected by the intake refrigerant pressure sensor 62 is greater than the atmospheric pressure, and the process proceeds to S18.
In S18, the expansion valve opening control for controlling the opening of the second expansion valve 46 and / or the compressor discharge capacity control for controlling the discharge capacity of the compressor 44 are performed, and the suction refrigerant pressure Pcs> 0 MPaG, and After the refrigerant flow rate is controlled so that the refrigerant flow rate F is controlled in the refrigerant flow rate range A of FIG. 6, the process returns to S11 again, and thereafter, steps S11 to S18 are repeatedly executed at a predetermined cycle.

  As described above, in the present embodiment, as in the case of the first embodiment, even if the heat exchanger is designed to function as a condenser, the above-described refrigerant flow rate control is performed during the heating operation. However, the pressure loss ΔPe in the outdoor heat exchanger 48 can be reduced, and air, moisture, dust and the like can be reliably prevented from entering the refrigerant pipe 40 of the heat pump cycle 4 during heating operation. High-efficiency operation of the vehicle air conditioner 1 can be realized.

  Particularly in the case of the present embodiment, the sum of the refrigerant pressure loss ΔPe estimated in S15 and the outlet refrigerant pressure Pee estimated in S16 is estimated as the inlet refrigerant pressure Pei, and the inlet refrigerant pressure Pei is the refrigerant saturated vapor pressure Po. When it is determined that the refrigerant flow rate is determined as described above, it is possible to determine whether or not the refrigerant flow rate control is necessary without providing a sensor for detecting the inlet refrigerant pressure Pei by performing the refrigerant flow rate control. A highly efficient operation of the vehicle air conditioner 1 can be realized with a simple configuration.

Although the description of the embodiment of the present invention has been completed above, the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention.
For example, the relationship diagrams of FIGS. 4 to 6 are those in which the gradient changes depending on the specifications of the outdoor heat exchanger 48, and are not limited to these diagrams.
The present invention is most preferably applied to an electric vehicle. However, the present invention is also suitable for a diesel vehicle equipped with a hybrid vehicle or a diesel engine in which the waste heat of the engine is not so much.

1,70 Vehicle air conditioner 2 HVAC unit 4 Heat pump cycle 10 Air flow path 26 Second heat exchanger (heat exchanger)
40 Refrigerant piping (refrigerant flow path)
44 Electric compressor (compressor)
46 Second expansion valve (expansion valve)
48 outdoor heat exchanger 58 outside air temperature sensor (outside air temperature detecting means, outside air refrigerant state detecting means)
60 Inlet refrigerant temperature sensor (inlet refrigerant state detection means)
62 Suction refrigerant pressure sensor (suction refrigerant pressure detection means)
63 Control unit (refrigerant flow control means)
72 Intake refrigerant temperature / pressure sensor (intake refrigerant state detection means)
74 Rotational speed sensor (Rotational speed detection means)

Claims (7)

An HVAC unit that blows out temperature-adjusted air into the passenger compartment by a heat exchanger disposed in the air flow path;
A heat pump cycle in which a refrigerant, a heat exchanger, an expansion valve, and an outdoor heat exchanger for exchanging heat between the refrigerant and outside air are sequentially inserted in the refrigerant flow path;
Outside temperature detecting means for detecting outside temperature;
An inlet refrigerant state detecting means for detecting an inlet refrigerant state value on the inlet side of the outdoor heat exchanger;
An outside air refrigerant state detecting means for detecting an outside air refrigerant state value in the outside air based on the outside air temperature detected by the outside air temperature detecting means;
An allowable pressure loss estimating means for estimating an allowable pressure loss in the outdoor heat exchanger at the outside air temperature detected by the outside air temperature detecting means;
Allowable refrigerant flow rate estimating means for estimating an allowable refrigerant flow rate flowing through the outdoor heat exchanger based on the allowable pressure loss estimated by the allowable pressure loss estimation means;
A refrigerant flow rate at which the refrigerant temperature is less than the outside air temperature and the refrigerant flow rate is equal to or less than the allowable refrigerant flow rate based on the outside air temperature detected by the outside air temperature detection unit and the allowable refrigerant flow rate detected by the allowable refrigerant flow rate estimation unit Refrigerant flow range setting means for setting the range;
When the inlet refrigerant state value detected by the inlet refrigerant state detector is equal to or greater than the outside refrigerant state value detected by the outside refrigerant state detector, the refrigerant is within the refrigerant flow range set by the refrigerant flow range setting unit. A vehicle air conditioner comprising a refrigerant flow rate control means for controlling the flow rate. The inlet refrigerant state detection means detects an inlet refrigerant temperature on the inlet side of the outdoor heat exchanger as the inlet refrigerant state value,
The outside air refrigerant state detecting means detects the outside air temperature detected by the outside air temperature detecting means as the outside air refrigerant state value,
The vehicle air conditioner according to claim 1, wherein the refrigerant flow rate control unit controls the refrigerant flow rate within the refrigerant flow rate control range when the inlet refrigerant temperature is equal to or higher than the outside air temperature. The inlet refrigerant state detection means detects an inlet refrigerant pressure on the inlet side of the outdoor heat exchanger as the inlet refrigerant state value,
The outside air refrigerant state detecting means detects a saturated vapor pressure of the refrigerant at the outside air temperature detected by the outside air temperature detecting means as the outside air refrigerant state value,
2. The vehicle air conditioner according to claim 1, wherein the refrigerant flow rate control unit controls the refrigerant flow rate within the refrigerant flow rate control range when the inlet refrigerant pressure becomes equal to or higher than the saturated vapor pressure. Intake refrigerant state detection means for detecting the intake refrigerant temperature and the intake refrigerant pressure on the intake side of the compressor;
Suction refrigerant density estimation means for estimating the suction refrigerant density on the suction side of the compressor based on the suction refrigerant temperature and the suction refrigerant pressure detected by the suction refrigerant state detection means;
A rotational speed detection means for detecting the rotational speed of the compressor;
Refrigerant flow estimation means for estimating the refrigerant flow rate circulating through the refrigerant flow path based on the suction refrigerant density detected by the suction refrigerant state detection means and the rotation speed detected by the rotation speed detection means;
Refrigerant pressure loss estimation means for estimating refrigerant pressure loss in the outdoor heat exchanger based on the refrigerant flow rate estimated by the refrigerant flow rate estimation means;
An outlet refrigerant pressure detecting means for detecting an outlet refrigerant pressure on the outlet side of the outdoor heat exchanger based on the outside air temperature detected by the outside air temperature detecting means and the refrigerant flow rate estimated by the refrigerant flow rate estimating means,
The inlet refrigerant state detection means detects the sum of the refrigerant pressure loss estimated by the refrigerant pressure loss estimation means and the outlet refrigerant pressure detected by the outlet refrigerant pressure detection means as the estimated inlet refrigerant pressure. The vehicle air conditioner according to claim 3. An intake refrigerant pressure detecting means for detecting an intake refrigerant pressure on the intake side of the compressor;
5. The refrigerant flow rate control unit controls the refrigerant flow rate so that the suction refrigerant pressure detected by the suction refrigerant pressure detection unit becomes larger than the atmospheric pressure. 6. Vehicle air conditioner.   The vehicle air conditioner according to any one of claims 1 to 5, wherein the refrigerant flow rate control unit performs expansion valve opening degree control for controlling a refrigerant flow rate by controlling an opening degree of the expansion valve. .   The vehicle air conditioner according to any one of claims 1 to 6, wherein the refrigerant flow rate control unit performs compressor discharge capacity control for controlling a refrigerant flow rate by controlling a discharge capacity of the compressor. .

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