JP5713316B2 - Air conditioner for vehicles - Google Patents

Description

  The present invention relates to a vehicle air conditioner applicable to, for example, an electric vehicle.

  Conventionally, in this type of vehicle air conditioner, a compressor that compresses and discharges a refrigerant, a radiator that is provided on the vehicle interior side and dissipates the refrigerant, and a heat absorption that is provided on the vehicle interior side and absorbs the refrigerant. There is known a device provided with a heater and an outdoor heat exchanger that is provided outside the passenger compartment and dissipates or absorbs heat from the refrigerant (see, for example, Patent Document 1).

  In the vehicle air conditioner, a heating operation in which the refrigerant discharged from the compressor radiates heat in the radiator, and the refrigerant radiated in the radiator absorbs heat in the outdoor heat exchanger; and the refrigerant discharged from the compressor in the radiator It is known to perform a dehumidifying heating operation in which heat is radiated and a part of the refrigerant radiated in the radiator is absorbed in the heat absorber and other refrigerant is absorbed in the outdoor heat exchanger.

JP 2000-25446 A

In the case of the heating operation of the vehicle air conditioner, it is necessary to control the heat radiation amount in the radiator. Further, in the case of the dehumidifying heating operation, it is necessary to control the heat dissipation amount in the radiator and the heat absorption amount in the heat absorber. In order to control the amount of heat dissipation in the radiator during heating operation, the amount of heat dissipation in the radiator during dehumidifying heating operation, and the amount of heat absorbed in the heat absorber, it is necessary to secure an appropriate amount of heat absorption in the outdoor heat exchanger. is there.
However, in the vehicle air conditioner, a capillary tube that cannot adjust the opening degree of the refrigerant flow path is used as means for reducing the pressure of the refrigerant flowing into the outdoor heat exchanger. For this reason, since it is difficult for an air conditioner for a vehicle to achieve an optimum heat absorption amount in an outdoor heat exchanger, control of the heat dissipation amount in a radiator during heating operation, and heat dissipation amount in a radiator during dehumidification heating operation It is difficult to control the amount of heat absorbed by the heat absorber.

  The object of the present invention is to optimally adjust the heat absorption amount in the outdoor heat exchanger, so that the optimum heat radiation amount in the radiator during the heating operation, the optimum heat radiation amount and the heat absorption in the radiator during the dehumidifying heating operation. An object of the present invention is to provide an air conditioner for a vehicle that can obtain an optimum heat absorption amount in a container.

In order to achieve the above object, the present invention provides a compressor that compresses and discharges a refrigerant, a radiator that is provided on the vehicle interior side and dissipates the refrigerant, and a heat absorption that is provided on the vehicle interior side and absorbs the refrigerant. And an outdoor heat exchanger provided on the outside of the passenger compartment to dissipate or absorb heat from the refrigerant. The refrigerant discharged from the compressor is dissipated in the heat dissipator, and the refrigerant dissipated in the heat dissipator Heating operation that absorbs heat in the air, heat release from the refrigerant discharged from the compressor, dehumidification that causes the heat absorber to absorb part of the heat dissipated in the heat sink, and absorbs other refrigerant in the outdoor heat exchanger A vehicle air conditioner that performs heating operation and is provided in a refrigerant flow passage on the refrigerant inflow side of an outdoor heat exchanger, and detects an expansion valve having a variable valve opening and an evaporation temperature of the refrigerant in the heat absorber. You A predetermined value is set as the target superheat degree of the refrigerant in the outdoor heat exchanger during the heating operation with the heat absorber temperature sensor, and is calculated based on the detected temperature of the heat absorber temperature sensor and the target temperature of the heat absorber during the dehumidifying heating operation. The target superheat degree setting means for setting the value as the target superheat degree of the refrigerant in the outdoor heat exchanger, the superheat degree calculation means for calculating the superheat degree of the refrigerant flowing out of the outdoor heat exchanger, and the target superheat degree setting means Valve opening degree control means for controlling the valve opening degree of the expansion valve based on the target degree of superheat and the degree of superheat calculated by the degree of superheat calculation means, and the valve opening degree control means is a target superheat degree setting means. Feedforward target value calculation means for calculating a feedforward target value related to the opening degree of the expansion valve based on the target superheat degree set by Responsiveness target value calculation means for calculating a target value of responsiveness to the target superheat degree based on the set target superheat degree, and the responsiveness target value and superheat degree calculation means calculated by the responsiveness target value calculation means Feedback target value calculation means for calculating a feedback target value related to the valve opening of the expansion valve based on the calculated degree of superheat of the refrigerant flowing out of the outdoor heat exchanger, and calculated by the feedforward target value calculation means The valve opening degree of the expansion valve is controlled based on the feedforward target value and the feedback target value calculated by the feedback calculation means .

  As a result, the degree of superheat of the refrigerant flowing out of the outdoor heat exchanger is optimally maintained, so that an optimum heat absorption amount can be obtained in the outdoor heat exchanger.

  According to the present invention, an optimum heat absorption amount can be obtained in the outdoor heat exchanger, so that the temperature and humidity environment in the passenger compartment can be maintained in a good state.

It is a schematic block diagram of the vehicle air conditioner which shows 1st Embodiment of this invention. It is a block diagram which shows a control system. It is a schematic block diagram of the vehicle air conditioner which shows a cooling operation and a dehumidification cooling operation. It is a schematic block diagram of the vehicle air conditioner which shows heating operation. It is a schematic block diagram of the air conditioning apparatus for vehicles which shows a dehumidification heating operation. It is a schematic block diagram of the vehicle air conditioner which shows a defrost driving | operation. It is a flowchart which shows a superheat degree control process. It is a flowchart which shows the superheat degree control process of 2nd Embodiment of this invention.

  1 to 7 show a first embodiment of the present invention.

  As shown in FIG. 1, the vehicle air conditioner of the present invention includes an air conditioning unit 10 provided in a vehicle interior, and a refrigerant circuit 20 configured across the vehicle interior and the exterior of the vehicle interior.

  The air conditioning unit 10 has an air flow passage 11 for circulating air supplied into the vehicle interior. On one end side of the air flow passage 11, an outside air intake port 11 a for allowing the air outside the vehicle interior to flow into the air flow passage 11, an inside air intake port 11 b for allowing the air inside the vehicle interior to flow into the air flow passage 11, Is provided. Further, on the other end side of the air flow passage 11, a foot outlet 11 c that blows out air flowing through the air flow passage 11 toward the feet of the passengers in the passenger compartment, and air flowing through the air flow passage 11 are supplied to the vehicle. A vent outlet 11d that blows out toward the upper body of the passenger in the room, and a differential outlet 11e that blows out the air flowing through the air flow passage 11 toward the surface of the vehicle windshield toward the vehicle interior side. ing.

  On one end side of the air flow passage 11, an indoor blower 12 such as a sirocco fan for circulating air from one end side of the air flow passage 11 toward the other end side is provided. This indoor blower 12 is driven by an electric motor 12a.

  On one end side of the air flow passage 11, there is provided an inlet switching damper 13 that can open one of the outside air inlet 11 a and the inside air inlet 11 b and close the other. The suction port switching damper 13 is driven by an electric motor 13a. When the inside air suction port 11b is closed by the suction port switching damper 13 and the outside air suction port 11a is opened, an outside air supply mode in which air flows from the outside air suction port 11a into the air flow passage 11 is set. Further, when the outside air suction port 11a is closed by the suction port switching damper 13 and the inside air suction port 11b is opened, the inside air circulation mode in which air flows from the inside air suction port 11b into the air flow passage 11 is set. Further, when the suction port switching damper 13 is positioned between the outside air suction port 11a and the inside air suction port 11b, and the outside air suction port 11a and the inside air suction port 11b are opened, the outside air suction port 11a by the suction port switching damper 13 is opened. And the inside / outside air suction mode in which air flows into the air flow passage 11 from the outside air suction port 11a and the inside air suction port 11b at a ratio corresponding to the respective opening ratios of the inside air suction port 11b.

  The outlet switching dampers 13b, 13c, and 13d for opening and closing the outlets 11c, 11d, and 11e are provided at the foot outlet 11c, the vent outlet 11d, and the differential outlet 11e on the other end side of the air flow passage 11, respectively. Is provided. The outlet switching dampers 13b, 13c, and 13d are configured to be interlocked by a link mechanism (not shown), and are opened and closed by an electric motor 13e. Here, when the foot outlet 11c is opened by the outlet switching dampers 13b, 13c, and 13d, the vent outlet 11d is closed, and the differential outlet 11e is slightly opened, the air flowing through the air flow passage 11 is reduced. Most of the air is blown from the foot outlet 11c and the remaining air is blown from the differential outlet 11e. When the foot outlet 11c and the differential outlet 11e are closed by the outlet switching dampers 13b, 13c, and 13d and the vent outlet 11d is opened, all of the air flowing through the air flow passage 11 is vented 11d. It becomes the vent mode blown out from. Further, when the foot outlet 11c and the vent outlet 11d are opened by the outlet switching dampers 13b, 13c, and 13d and the differential outlet 11e is closed, the air flowing through the air flow passage 11 is moved to the foot outlet 11c and the vent. It becomes the bilevel mode which blows off from the blower outlet 11d. When the foot outlet 11c and the vent outlet 11d are closed by the outlet switching dampers 13b, 13c, and 13d and the differential outlet 11e is opened, the air flowing through the air flow passage 11 is blown out from the differential outlet 11e. It becomes the differential mode. When the vent outlet 11d is closed by the outlet switching dampers 13b, 13c, and 13d and the foot outlet 11c and the differential outlet 11e are opened, the air flowing through the air flow passage 11 is transferred to the foot outlet 11c and the differential outlet 11c. It becomes the differential foot mode which blows off from the blower outlet 11e. In the bi-level mode, the air flow passage 11 and the foot blowing are such that the temperature difference between the air blown from the foot blower outlet 11c is higher than the temperature of the air blown from the vent blower outlet 11d. The positional relationship and structure of the outlet 11c, the vent outlet 11d, a heat absorber and a radiator described later are provided.

  The air flow passage 11 on the downstream side in the air flow direction of the indoor blower 12 is provided with a heat absorber 14 for cooling and dehumidifying the air flowing through the air flow passage 11. A heat radiator 15 for heating the air flowing through the air flow passage 11 is provided in the air flow passage 11 on the downstream side in the air flow direction of the heat absorber 14. The heat absorber 14 and the heat radiator 15 are heat exchangers each including a fin and a tube for exchanging heat between the refrigerant and the air flowing through the air flow passage 11.

  The air flow path 11 between the heat absorber 14 and the heat radiator 15 is provided with an air mix damper 16 for adjusting a ratio of heating in the heat radiator 15 of the air flowing through the air flow path 11. The air mix damper 16 is driven by an electric motor 16a. Since the air mix damper 16 is positioned upstream of the radiator 15 in the air flow passage 11, the ratio of air to be heat exchanged in the radiator 15 is reduced, and the air mix damper 16 is disposed on a portion other than the radiator 15 in the air flow passage 11. By moving, the ratio of the air that exchanges heat in the radiator 15 increases. The air mix damper 16 closes the upstream side of the radiator 15 in the air flow passage 11 and opens the portion other than the radiator 15 so that the opening degree becomes 0%, and the upstream side of the radiator 15 in the air flow passage 11. Is opened and the opening is 100% with the portion other than the radiator 15 closed.

  The refrigerant circuit 20 flows out of the heat absorber 14, the radiator 15, the compressor 21 for compressing the refrigerant, the outdoor heat exchanger 22 for exchanging heat between the refrigerant and the air outside the passenger compartment, and the radiator 15. Or an internal heat exchanger 23 for exchanging heat between the refrigerant flowing through the outdoor heat exchanger 22 and the refrigerant flowing out of the heat absorber 14, an electric three-way valve 24 for switching the refrigerant flow path, first to first 4 solenoid valves 25a-25d and first to second check valves 26a-26b, first and second expansion valves 27a, 27b for depressurizing the circulating refrigerant, and receiver tank 28 for storing surplus refrigerant. And an accumulator 29 for separating the gaseous refrigerant from the liquid refrigerant and preventing the liquid refrigerant from being sucked into the compressor 21, and these are connected by a copper tube or an aluminum tube. The compressor 21 and the outdoor heat exchanger 22 are disposed outside the passenger compartment. The compressor 21 is driven by an electric motor 21a. The outdoor heat exchanger 22 is provided with an outdoor blower 30 for exchanging heat between air outside the passenger compartment and the refrigerant when the vehicle is stopped. The outdoor blower 30 is driven by an electric motor 30a. The first expansion valve 27a is an electronic expansion valve capable of adjusting the valve opening degree.

  Specifically, the refrigerant flow path 20 a is provided by connecting the refrigerant inflow side of the radiator 15 to the refrigerant discharge side of the compressor 21. Further, a refrigerant flow passage 20 b is provided on the refrigerant outflow side of the radiator 15 by connecting the refrigerant inflow side of the outdoor heat exchanger 22. A three-way valve 24 is provided in the refrigerant flow passage 20b, and one refrigerant outflow side and the other refrigerant outflow side of the three-way valve 24 are connected in parallel to the refrigerant inflow side of the outdoor heat exchanger 22, respectively. , 20d are provided. In the refrigerant flow passage 20d, a receiver tank 28, a first expansion valve 27a, and a first check valve 26a are provided in order from the upstream side in the refrigerant flow direction. The refrigerant outflow side of the outdoor heat exchanger 22 is connected in parallel with the refrigerant suction side of the compressor 21 and between the three-way valve 24 of the refrigerant flow passage 20d and the receiver tank 28, respectively. Flow passages 20e and 20f are provided. The refrigerant flow passage 20e is provided with a first electromagnetic valve 25a and an accumulator 29 in order from the upstream side in the refrigerant flow direction. The refrigerant flow passage 20f is provided with a second electromagnetic valve 25b and a second check valve 26b in order from the upstream side in the refrigerant flow direction. Further, the high-pressure refrigerant inflow side of the internal heat exchanger 23 is connected between the receiver tank 28 of the refrigerant flow passage 20d and the first expansion valve 27a, and a refrigerant flow passage 20g is provided. A third electromagnetic valve 25c is provided in the refrigerant flow passage 20g. A refrigerant flow passage 20 h is provided on the high-pressure refrigerant outflow side of the internal heat exchanger 23 by connecting the refrigerant inflow side of the heat absorber 14. A second expansion valve 27b is provided in the refrigerant flow passage 20h. A refrigerant flow passage 20 i is provided on the refrigerant outflow side of the heat absorber 14 by connecting the low-pressure refrigerant inflow side of the internal heat exchanger 23. A refrigerant flow passage 20j is provided on the low-pressure refrigerant outflow side of the internal heat exchanger 23 by connecting the first electromagnetic valve 25a and the accumulator 29 of the refrigerant flow passage 20e. The refrigerant flow passage 20a is provided with a refrigerant flow passage 20k by connecting the refrigerant inflow side of the outdoor heat exchanger 22 to the refrigerant flow passage 20a. A fourth solenoid valve 25d is provided in the refrigerant flow passage 20k.

  Furthermore, the vehicle air conditioner includes a controller 40 for performing control so that the temperature and humidity in the passenger compartment are set to the set temperature and the set humidity.

  The controller 40 has a CPU, ROM, and RAM. When the controller 40 receives an input signal from a device connected to the input side, the CPU reads a program stored in the ROM based on the input signal, and stores a state detected by the input signal in the RAM. The output signal is transmitted to a device connected to the output side.

  On the output side of the controller 40, as shown in FIG. 2, an electric motor 12a for driving the indoor fan 12, an electric motor 13a for driving the inlet switching damper 13, and an electric motor for driving the outlet switching dampers 13b, 13c, 13d. Motor 13e, electric motor 16a for driving air mix damper 16, electric motor 21a for driving compressor 21, three-way valve 24, first to fourth electromagnetic valves 25a to 25d, first expansion valve 27a, outdoor fan 30 driving The electric motor 30a is connected.

  On the input side of the controller 40, as shown in FIG. 2, an outside air temperature sensor 41 for detecting the temperature Tam outside the passenger compartment, an inside air temperature sensor 42 for detecting the temperature Tr inside the passenger compartment, and the air flow passage 11 are provided. Intake air temperature sensor 43 for detecting the temperature T of the inflowing air, cooling air temperature sensor 44 for detecting the temperature Te of the air after being cooled in the heat absorber 14, and air after being heated in the radiator 15 A heated air temperature sensor 45 for detecting the temperature Tc of the vehicle, an indoor air humidity sensor 46 for detecting the humidity Th in the vehicle interior, and a refrigerant for detecting the temperature Thex of the refrigerant after heat exchange in the outdoor heat exchanger 22 A temperature sensor 47, a photosensor-type solar sensor 48 for detecting the solar radiation amount Ts, a speed sensor 49 for detecting the vehicle speed V, a target set temperature Ts Operation unit 50 for setting a mode related switching of t and operation, a pressure sensor 51 for detecting the pressure P of the refrigerant in the outdoor heat exchanger 22 is connected.

  In the vehicle air conditioner configured as described above, cooling operation, dehumidifying cooling operation, heating operation, dehumidifying heating operation, and defrosting operation are performed. Hereinafter, each operation will be described.

In the cooling operation and the dehumidifying cooling operation, in the refrigerant circuit 20, the flow path of the three-way valve 24 is set to the refrigerant flow passage 20c side, the second and third electromagnetic valves 25b and 25c are opened, and the first and fourth electromagnetics are opened. The valves 25a and 25d are closed, and the compressor 21 is operated.
Thereby, the refrigerant discharged from the compressor 21 is, as shown in FIG. 3, the refrigerant flow passage 20a, the radiator 15, the refrigerant flow passages 20b and 20c, the outdoor heat exchanger 22, and the refrigerant flow passages 20f, 20d and 20g. The high-pressure side of the internal heat exchanger 23, the refrigerant flow passage 20h, the heat absorber 14, the refrigerant flow passage 20i, the low-pressure side of the internal heat exchanger 23, and the refrigerant flow passages 20j and 20e flow in this order and are sucked into the compressor 21. The The refrigerant flowing through the refrigerant circuit 20 radiates heat in the outdoor heat exchanger 22 and absorbs heat in the heat absorber 14. Further, when the air mix damper 16 is opened as a dehumidifying and cooling operation, the radiator 15 also radiates heat.

  At this time, in the air conditioning unit 10 in the cooling operation, the air in the air flow passage 11 circulated by operating the indoor fan 12 is cooled by exchanging heat with the refrigerant in the heat absorber 14, and the temperature inside the vehicle interior is set to a set temperature. Therefore, the air is blown into the passenger compartment as air having a target blowing temperature TAO that is the temperature of the air to be blown out from the blowout ports 11c, 11d, and 11e.

  Further, in the air conditioning unit 10 in the dehumidifying and cooling operation, the air flowing through the air flow passage 11 by operating the indoor blower 12 is dehumidified by being cooled by exchanging heat with the refrigerant that absorbs heat in the heat absorber 14. . The air dehumidified in the heat absorber 14 is heated by exchanging heat with the refrigerant that dissipates heat in the radiator 15 and is blown into the passenger compartment as air at the target blowing temperature TAO.

In the heating operation, in the refrigerant circuit 20, the flow path of the three-way valve 24 is set on the refrigerant flow passage 20d side, the first electromagnetic valve 25a is opened, the second to fourth electromagnetic valves 25b to 25d are closed, and the compression is performed. The machine 21 is operated.
As a result, the refrigerant discharged from the compressor 21 flows in the order of the refrigerant flow passage 20a, the radiator 15, the refrigerant flow passages 20b and 20d, the outdoor heat exchanger 22, and the refrigerant flow passage 22e as shown in FIG. And sucked into the compressor 21. The refrigerant flowing through the refrigerant circuit 20 dissipates heat in the radiator 15 and absorbs heat in the outdoor heat exchanger 22.

  At this time, in the air conditioning unit 10, the air in the air flow passage 11 circulated by operating the indoor fan 12 is heated by exchanging heat with the refrigerant in the radiator 15 without exchanging heat with the refrigerant in the heat absorber 14. Then, the air becomes the target blowing temperature TAO and is blown into the passenger compartment.

In the dehumidifying and heating operation, in the refrigerant circuit 20, the flow path of the three-way valve 24 is set on the refrigerant flow path 20d side, the first and third electromagnetic valves 25a and 25c are opened, and the second and fourth electromagnetic valves 25b, 25d is closed and the compressor 21 is operated.
Thereby, as shown in FIG. 5, the refrigerant | coolant discharged from the compressor 21 distribute | circulates the refrigerant | coolant flow path 20a, the heat radiator 15, and the refrigerant | coolant flow paths 20b and 20d in order. A part of the refrigerant flowing through the refrigerant flow passage 20d flows through the outdoor heat exchanger 22 and the refrigerant flow passage 20e in this order, and is sucked into the compressor 21. Other refrigerants flowing through the refrigerant flow passage 20d include the refrigerant flow passage 20g, the high pressure side of the internal heat exchanger 23, the refrigerant flow passage 20h, the heat absorber 14, the refrigerant flow passage 20i, and the low pressure side of the internal heat exchanger 23. Then, the refrigerant flows through the refrigerant flow passages 20j and 20e in this order and is sucked into the compressor 21. The refrigerant flowing through the refrigerant circuit 20 radiates heat in the radiator 15 and absorbs heat in the heat absorber 14 and the outdoor heat exchanger 22.

  At this time, in the air conditioning unit 10, the air in the air flow passage 11 circulated by operating the indoor blower 12 is dehumidified by being cooled by heat exchange with the refrigerant in the heat absorber 14. The air dehumidified in the heat absorber 14 is heated when a part of the air exchanges heat with the refrigerant in the radiator 15, and is blown into the vehicle interior as air at the target blowing temperature TAO.

In the defrosting operation, in the refrigerant circuit 20, the flow path of the three-way valve 24 is set on the refrigerant flow passage 20d side, the first and fourth electromagnetic valves 25a and 25d are opened, and the second and third electromagnetic valves 25b, 25c is closed and the compressor 21 is operated.
Thereby, a part of the refrigerant discharged from the compressor 21 flows into the outdoor heat exchanger 22 through the refrigerant flow passage 20a, the radiator 15, and the refrigerant flow passages 20b and 20d in this order, as shown in FIG. To do. The other refrigerant discharged from the compressor 21 flows through the refrigerant flow passages 20a and 20k and flows into the outdoor heat exchanger 22. The refrigerant flowing out of the outdoor heat exchanger 22 flows through the refrigerant flow passage 20e and is sucked into the compressor 21. The refrigerant flowing through the refrigerant circuit 20 radiates heat in the radiator 15 and absorbs heat in the outdoor heat exchanger 22 simultaneously with heat radiation.

  At this time, in the air conditioning unit 10, the air in the air flow passage 11 circulated by operating the indoor blower 12 does not exchange heat with the refrigerant in the heat absorber 14, but exchanges heat with the refrigerant that radiates heat in the radiator 15. Is heated and blown into the passenger compartment.

  When the auto air conditioner switch of the operation unit 50 is set to the on state, the controller 40 performs the cooling operation, the dehumidifying and cooling operation, the heating operation, the dehumidifying heating operation, and the defrosting operation in environmental conditions such as the temperature inside and outside the vehicle interior. The operation switching control process for switching based on the is performed.

  Further, the controller 40 performs switching between the foot mode, the vent mode, and the bi-level mode in accordance with the target blowing temperature TAO in each operation that is switched by the operation switching control process. Specifically, the foot mode is set when the target blowing temperature TAO is a high temperature such as 40 ° C. or higher. Further, the controller 40 sets the vent mode when the target blowing temperature TAO becomes a low temperature such as less than 25 ° C., for example. Further, the controller 40 sets the bi-level mode when the target blowing temperature TAO is a temperature between the target blowing temperature TAO for which the foot mode is set and the target blowing temperature TAO for which the vent mode is set.

  Further, the controller 40 switches the modes of the air outlets 11c, 11d, and 11e by the air outlet switching dampers 13b, 13c, and 13d, and sets the temperature of the air that is blown out from the air outlets 11c, 11d, and 11e as the target air outlet temperature TAO. Therefore, the opening degree of the air mix damper 16 is controlled.

  In addition, the controller 40 performs superheat degree control processing for setting the refrigerant flowing out of the outdoor heat exchanger 22 to an optimum superheat degree during the heating operation and the dehumidifying heating operation. The operation of the controller 40 at this time will be described with reference to the flowchart of FIG.

(Step S1)
In step S1, the CPU sets a predetermined value A (for example, 2 ° C. to 5 ° C.) as the target superheat degree SHt during the heating operation, and sets the temperature Tam outside the passenger compartment and the heat absorber 14 during the dehumidifying heating operation. A value calculated based on the target temperature Tet is set as the target superheat degree SHt.

(Step S2)
In step S2, the CPU calculates a correction amount H with respect to the target superheat degree SHt set in step S1, based on the temperature Te of the heat absorber 14 and the target temperature Tet of the heat absorber 14.
Specifically, it is determined whether or not the detected temperature Te of the cooling air temperature sensor 44 is equal to or lower than a temperature obtained by subtracting a predetermined temperature α from the target temperature Tet (Tet−α). If the temperature Te is equal to or lower than Tet−α, the target The correction amount H (H <0) is used to reduce the degree of superheat SHt, and the correction amount H (H> 0) is used to increase the target superheat degree SHt when the temperature Te is greater than Tet-α.

(Step S3)
In step S3, the CPU calculates the corrected target superheat degree SHtc by adding the correction amount H to the target superheat degree SHt.

(Step S4)
In step S <b> 4, the CPU calculates the superheat degree SH of the refrigerant based on the refrigerant pressure P in the outdoor heat exchanger 22 and the refrigerant temperature Thex flowing out of the outdoor heat exchanger 22.

(Step S5)
In step S5, the CPU controls the valve opening degree of the first expansion valve 27a based on the corrected target superheat degree SHtc and the superheat degree SH.

  As described above, according to the vehicle air conditioner of the present embodiment, the predetermined value A is set during the heating operation, and the temperature Tam outside the passenger compartment and the target temperature Tet of the heat absorber 14 are set during the dehumidifying heating. The superheat degree SH of the refrigerant calculated based on the target superheat degree SHt for which the value calculated based on this is set, the pressure P of the refrigerant in the outdoor heat exchanger 22 and the temperature Thex of the refrigerant flowing out of the outdoor heat exchanger 22 The valve opening degree of the first expansion valve 27a is controlled. Thus, by controlling the degree of superheat SH of the refrigerant flowing out of the outdoor heat exchanger 22, it is possible to obtain an optimum heat absorption amount in the outdoor heat exchanger 22, so that the temperature Tr and humidity Th in the vehicle interior are good. It becomes possible to maintain the state.

FIG. 8 shows a second embodiment of the present invention. In addition, the same code | symbol is attached | subjected and shown to the component similar to the said embodiment.

  The vehicle air conditioner of this embodiment has the same configuration as that of the first embodiment, and the controller 40 performs superheat degree control processing as shown in the flowchart shown in FIG.

(Step S11)
In step S11, the CPU sets a predetermined value A (2 ° C. to 5 ° C.) as the target superheat degree SHt during the heating operation, and the temperature Tam outside the vehicle compartment and the target temperature of the heat absorber 14 during the dehumidifying heating operation. A value calculated based on Tet is set as the target superheat degree SHt.

(Step S12)
In step S12, the CPU calculates a feedforward target value EXVtgtFF related to the valve opening degree of the first expansion valve 27a based on the target superheat degree SHt set in step S11.
The feedforward target value EXVtgtFF is calculated based on the temperature Tam outside the passenger compartment, the voltage BLV of the electric motor 12a for driving the indoor fan 12, and the rotation speed Nc of the electric motor 21a for driving the compressor 21 (EXVtgtFF = Ka.times.Tam + Kb.times.BLV + Kc.times.Nc + d, Ka, Kb, Kc, d: respective preset constants).

(Step S13)
In step S13, the CPU calculates a target value SHtgtf of responsiveness to the target superheat degree SHt based on the target superheat degree SHt set in step S11.
The target value SHtgtf of responsiveness is obtained by performing a process such that the response becomes a first-order lag with respect to the target superheat degree SHt.

(Step S14)
In step S <b> 14, the CPU calculates the superheat degree SH of the refrigerant based on the refrigerant pressure P in the outdoor heat exchanger 22 and the refrigerant temperature Thex flowing out of the outdoor heat exchanger 22.

(Step S15)
In step S15, the CPU calculates a feedback target value EXVtgtFB related to the valve opening degree of the first expansion valve 27a based on the response target value SHtgtf calculated in step S13 and the refrigerant superheat degree SH calculated in step S14. .
The feedback target value EXVtgtFB is an output value of proportional integral control (PI control) calculated based on the target value SHtgtf of responsiveness and the superheat degree SH of the refrigerant calculated in step S14 (EXVtgtFB = EXVtgtfbp + EXVtgtfbp = EXVtgtfbp = * (SHtgtf-SH), EXVtgtfbi = EXVtgtfbi_n-1 + Kp / Ti * (SHtgtf-SH), Kp: constant as a proportional gain, Ti: integration time, EXVtgtfbi_n-1: previous value of EXVtgtfbi).

(Step S16)
In step S16, the CPU controls the valve opening degree of the first expansion valve 27a based on the feedforward target value EXVtgtFF calculated in step S12 and the feedback target value EXVtgtFB calculated in step S15.

  Thus, according to the vehicle air conditioner of the present embodiment, as in the above-described embodiment, the superheat degree SH of the refrigerant flowing out of the outdoor heat exchanger 22 is controlled, so that it is optimal for the outdoor heat exchanger 22. Therefore, it is possible to maintain the temperature Tr and the humidity Th in the vehicle interior in a good state.

  Further, a feedforward target value EXVtgtFF related to the valve opening degree of the first expansion valve 27a is calculated based on the target superheat degree SHt, a responsive target value SHtgtf for the target superheat degree SHt is calculated, and the responsive target value SHtgtf and A feedback target value EXVtgtFB relating to the valve opening degree of the first expansion valve 27a is calculated based on the superheat degree SH of the refrigerant, and the valve opening degree of the first expansion valve 27a is controlled based on the feedforward target value EXVtgtFF and the feedback target value EXVtgtFB. doing. Thereby, it becomes possible to further improve the control performance of the temperature Tr and the humidity Th in the passenger compartment.

  In the above embodiment, the amount of heat exchanged between the air flowing through the air flow passage 11 and the refrigerant in the radiator 15 is used as a heat source for heating, dehumidifying heating, and dehumidifying cooling. However, when the amount of heat is insufficient May be provided with an auxiliary heat source. For example, an electric heater capable of directly heating the air flowing through the air flow passage 11 in the air flow passage 1 as a heat source may be provided separately from the radiator 15. Further, a hot water circuit may be formed over the inside and outside of the air flow passage 11, and the hot water flowing through the hot water circuit may be heated outside the air flow passage 11 to dissipate heat in the air flow passage 11.

  In the refrigerant circuit 20, the three-way valve 24 is used to switch the refrigerant flow passages 20c, 20d. However, instead of the three-way valve 24, the refrigerant flow passages 20c, 20d are opened and closed by opening and closing two electromagnetic valves. You may make it switch.

DESCRIPTION OF SYMBOLS 10 ... Air-conditioning unit, 14 ... Heat absorber, 15 ... Radiator, 20 ... Refrigerant circuit, 20a-20j ... Refrigerant flow path, 21 ... Compressor, 22 ... Outdoor heat exchanger, 24 ... Three-way valve, 25a-25d ... No. 1st-4th solenoid valve, 26a-26c ... 1st-3rd check valve, 27a ... 1st expansion valve, 27b ... 2nd expansion valve, 40 ... controller, 41 ... Outside temperature sensor, 42 ... Inside temperature sensor, DESCRIPTION OF SYMBOLS 43 ... Intake temperature sensor, 44 ... Cooling air temperature sensor, 45 ... Heated air temperature sensor, 46 ... Inside air humidity sensor, 47 ... Refrigerant temperature sensor, 48 ... Solar radiation sensor, 49 ... Speed sensor, 50 ... Operation part, 51 ... Pressure Sensor.

Claims (1)

A compressor that compresses and discharges the refrigerant;
A radiator that is provided in the passenger compartment and dissipates heat from the refrigerant;
A heat absorber provided on the vehicle interior side for absorbing heat from the refrigerant;
An outdoor heat exchanger that is provided outside the passenger compartment and dissipates or absorbs heat from the refrigerant,
Heating operation in which the refrigerant discharged from the compressor dissipates heat in the radiator, and the refrigerant dissipated in the radiator absorbs heat in the outdoor heat exchanger;
A vehicle that performs a dehumidifying heating operation in which a refrigerant discharged from a compressor is radiated in a radiator, and a part of the refrigerant radiated in the radiator is absorbed in a heat absorber and other refrigerant is absorbed in an outdoor heat exchanger. An air conditioner for use,
An expansion valve provided in the refrigerant flow passage on the refrigerant inflow side of the outdoor heat exchanger, and having a variable valve opening;
A heat absorber temperature sensor for detecting the evaporation temperature of the refrigerant in the heat absorber;
A predetermined value is set as the target superheat of the refrigerant in the outdoor heat exchanger during heating operation, and the value calculated based on the temperature detected by the heat absorber temperature sensor and the target temperature of the heat absorber during dehumidification heating operation Target superheat degree setting means for setting as a target superheat degree of the refrigerant in the condenser;
Superheat degree calculating means for calculating the degree of superheat of the refrigerant flowing out of the outdoor heat exchanger;
A valve opening degree control means for controlling the valve opening degree of the expansion valve based on the target superheat degree set by the target superheat degree setting means and the superheat degree calculated by the superheat degree calculation means,
The valve opening degree control means includes a feedforward target value calculation means for calculating a feedforward target value related to the valve opening degree of the expansion valve based on the target superheat degree set by the target superheat degree setting means, and a target superheat degree setting means. Calculated by the responsiveness target value calculation means for calculating the target value of the responsiveness to the target superheat degree based on the set target superheat degree, and the responsiveness target value and the superheat degree calculation means calculated by the responsiveness target value calculation means Feedback target value calculation means for calculating a feedback target value related to the valve opening of the expansion valve based on the degree of superheat of the refrigerant flowing out from the outdoor heat exchanger, and calculated by the feedforward target value calculation means The expansion valve based on the feedforward target value and the feedback target value calculated by the feedback calculation means Air conditioning apparatus for a vehicle and controls the valve opening degree.

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