Vehicle air conditioning system

Abstract

Vehicle air conditioning system, comprising: a compressor (21) configured to compress and expel a refrigerant; a radiator (15) that is provided in a vehicle interior and is configured to emit heat from the refrigerant; a heat exchanger (14) provided in the vehicle interior and configured to absorb heat into the refrigerant; and an external heat exchanger (22) provided outside the vehicle interior and configured to release heat from the refrigerant or to absorb heat into the refrigerant, the vehicle air conditioning system performs the following functions: a cooling operation to release the heat from the refrigerant discharged by the compressor (21) into the external heat exchanger (22), to decompress the refrigerant through a second expansion valve (27b), and to absorb the heat into the refrigerant in the heat exchanger (14); a cooling and dehumidifying operation to release the heat from the refrigerant discharged by the compressor (21) into the radiator (15) and the external heat exchanger (22), to decompress the refrigerant through the second expansion valve (27b), and to absorb the heat into the refrigerant in the heat exchanger (14); a heating operation to release the heat from the refrigerant discharged by the compressor (21) into the radiator (15), to decompress the refrigerant through a first expansion valve (27a), and to absorb the heat into the refrigerant in the external heat exchanger (22); and a heating and dehumidification operation to release the heat from the refrigerant discharged by the compressor (21) into the radiator (15), to decompress part of the refrigerant through the second expansion valve (27b), and to absorb the heat in the heat exchanger (14) into the refrigerant, while a remaining refrigerant is decompressed through the first expansion valve (27a) and then the heat is absorbed into the refrigerant in the outdoor heat exchanger (22), the vehicle air conditioning system further features: an on / off valve (25c) provided in a refrigerant flow passage (20g) to allow the refrigerant to flow into the heat exchanger (14), and configured to be able to open and close the refrigerant flow passage (20g); characterized by the fact that the vehicle air conditioning system also features: a cooled air temperature sensor (44) configured to detect a temperature (Te) of air that has been cooled in the heat exchanger (14); and a refrigerant flow restriction part which is configured, using the on / off valve (25c), to restrict the refrigerant flow into the heat exchanger (14) when the evaporation temperature detected by the chilled air temperature sensor (44) during the heating and dehumidifying operation is a predetermined temperature or lower.

Description

TECHNICAL FIELD

[0001] The present invention relates to a vehicle air conditioning device which is applicable, for example, to electric cars. STATE OF THE ART

[0002] Conventionally, a vehicle air conditioning device has been known as a type of device including: a compressor configured to compress and discharge a refrigerant; a radiator provided in the vehicle interior and configured to release the heat from the refrigerant; a heat exchanger provided in the vehicle interior and configured to absorb the heat in the refrigerant; and an outdoor heat exchanger provided outside the vehicle interior and configured to release the heat from the refrigerant or absorb the heat in the refrigerant (see, for example, JP 2000-025446 A).

[0003] It has been known that the vehicle air conditioning device performs a cooling operation by releasing the heat from the refrigerant discharged from the compressor into the outdoor heat exchanger and absorbing the heat in the heat exchanger into the refrigerant; a cooling and dehumidifying operation by releasing the heat from the refrigerant discharged from the compressor into the radiator and the outdoor heat exchanger and absorbing the heat in the heat exchanger into the refrigerant; a heating operation by releasing the heat from the refrigerant discharged from the compressor into the radiator and absorbing the heat in the outdoor heat exchanger into the refrigerant; and a heating and dehumidifying operation by releasing the heat from the refrigerant discharged from the compressor into the radiator and, while absorbing the heat in the outdoor heat exchanger into the remaining refrigerant, by absorbing the heat in the heat exchanger into a part of the refrigerant.

[0004] In addition, it has been conventionally known that this type of vehicle air conditioning device includes a compressor driven by an internal combustion engine as a power source of a vehicle; a radiator provided outside the vehicle interior; and a heat exchanger provided inside the vehicle interior. With this vehicle air conditioning device, a cooling operation is performed by: releasing heat from the refrigerant discharged from the compressor into the radiator; absorbing the heat in the heat exchanger into the refrigerant; and, after heat exchange in the heat exchanger with the refrigerant, supplying the air to the vehicle interior.In addition, such a conventional vehicle air conditioning device includes a heater core and performs a heating operation by: discharging waste heat from the cooling water used to cool the internal combustion engine in the heater core; and, after heat exchange with the cooling water in the heater core, blowing the air to the vehicle interior. Furthermore, such a conventional vehicle air conditioning device performs a heating and dehumidifying operation by: cooling the air to be supplied to the vehicle interior in the heat exchanger for dehumidification to a required absolute humidity; heating the cooled and dehumidified air in the heater core to a desired temperature; and blowing the heated air into the vehicle interior.

[0005] The above-mentioned vehicle air conditioning system uses the waste heat from the internal combustion engine as a heat source to heat the air during heating and heating and dehumidification operations. Electric cars generally use an electric motor as a power source, and it is difficult to capture the waste heat that can heat the air using the electric motor without an internal combustion engine. Therefore, the above-mentioned vehicle air conditioning system is not applicable to electric cars.

[0006] To address this issue, a vehicle air conditioning device applicable to electric cars has been known. The vehicle air conditioning device includes: a compressor configured to compress and discharge a refrigerant; a radiator provided in the vehicle interior and configured to release heat from a refrigerant; a heat exchanger provided in the vehicle interior and configured to absorb heat into the refrigerant; and an exterior heat exchanger provided outside the vehicle interior and configured to release heat from the refrigerant or absorb heat into the refrigerant.This vehicle air conditioning device performs: a heating operation by releasing the heat from the refrigerant discharged from the compressor into the radiator and by absorbing the heat in the outdoor heat exchanger into the refrigerant; a heating and dehumidifying operation by releasing the heat from the refrigerant discharged from the compressor into the radiator and by absorbing the heat in the heat exchanger and the outdoor heat exchanger, or at least in the heat exchanger, into the refrigerant; a cooling operation by releasing the heat from the refrigerant discharged from the compressor into the outdoor heat exchanger and by absorbing the heat in the heat exchanger into the refrigerant; and a cooling and dehumidifying operation by releasing the heat from the refrigerant discharged from the compressor into the radiator and the outdoor heat exchanger and by absorbing the heat in the heat exchanger into the refrigerant (see, for example, JP H06-278451 A).

[0007] Furthermore, as one type of device, there has been conventionally known a vehicle air conditioning device including a compressor configured to compress and discharge a refrigerant; a radiator provided in the vehicle interior and configured to release the heat from the refrigerant; a heat exchanger provided in the vehicle interior and configured to absorb the heat into the refrigerant; and an outdoor heat exchanger provided outside the vehicle interior and configured to release the heat from the refrigerant or absorb the heat into the refrigerant (see, for example, JP 2000-025446 A).

[0008] In addition, a vehicle air conditioning device has been known which performs a heating operation by releasing the heat from a refrigerant discharged from the compressor into the radiator and absorbing the heat in the outdoor heat exchanger into the refrigerant; and a heating and dehumidifying operation by releasing the heat from the refrigerant discharged from the compressor into the radiator and absorbing the heat in the heat exchanger into a part of the refrigerant, while absorbing the heat in the outdoor heat exchanger into the remaining refrigerant.

[0009] JP H08-282 262 A discloses a vehicle air conditioning device having the features according to the preamble of claim 1. SUMMARY OF THE INVENTIONTechnical Problem

[0010] With such a vehicle air conditioning system, the refrigerant releases heat during heating and dehumidification operations in the radiator and absorbs heat from the outside air in the outdoor heat exchanger. Therefore, when the outside air temperature is low, the evaporation temperature of the refrigerant in the outdoor heat exchanger drops. As a result, the evaporation temperature of the refrigerant in the heat exchanger also drops, so frost is likely to form on the heat exchanger.

[0011] This makes it difficult to control the temperature and humidity in the vehicle interior.

[0012] It is therefore an object of the present invention to provide a vehicle air conditioning device which can prevent frost from being formed on the heat exchanger under the condition that the outside air temperature is low.

[0013] The electric car consumes electrical energy to drive the vehicle during operation of the vehicle air conditioning system. Therefore, the proportion of energy consumption for the operation of the vehicle air conditioning system increases when the heating and dehumidification operations continue for a long time, which requires a large amount of electricity, especially among the operations of the vehicle air conditioning system. As a result, the vehicle's cruising range is likely to decrease.

[0014] It is therefore an object of the present invention to provide a vehicle air conditioning device that prevents the driving range of the vehicle from decreasing while the air conditioning operation in the vehicle interior continues.

[0015] During a heating operation of the vehicle air conditioning device, it is necessary to control the amount of heat released in the radiator. Meanwhile, during a heating and dehumidifying operation, it is necessary to control the amount of heat released in the radiator and the amount of heat absorbed in the heat exchanger. In order to control the amount of heat released in the radiator during a heating operation and to control the amount of heat released in the radiator and the amount of heat absorbed in the heat exchanger, it is necessary to ensure an appropriate amount of heat absorbed in the outdoor heat exchanger. However, the vehicle air conditioning device uses a capillary tube, which cannot adjust the opening of a refrigerant flow passage as a means for decompressing the refrigerant flowing into the outdoor heat exchanger.Therefore, it is difficult for the vehicle air conditioning system to acquire an appropriate amount of heat absorbed in the exterior heat exchanger. This makes it difficult to control the amount of heat released in the radiator during heating operation, and also makes it difficult to control the amount of heat released in the radiator and the amount of heat absorbed in the heat exchanger during heating and dehumidification operation.

[0016] It is therefore an object of the present invention to provide a vehicle air conditioning device which can acquire an appropriate amount of heat released in the radiator during a heating operation and can also acquire an appropriate amount of heat released in the radiator and an amount of heat absorbed in the heat exchanger during a heating and dehumidifying operation. Solution to the problem

[0017] To achieve the above-described objects, an exemplary vehicle air conditioning device not belonging to the invention includes: a compressor configured to compress and discharge a refrigerant; a radiator provided in a vehicle interior and configured to release heat from the refrigerant; a heat exchanger provided in the vehicle interior and configured to absorb the heat in the refrigerant; and an exterior heat exchanger provided outside the vehicle interior and configured to release the heat from the refrigerant or absorb the heat into the refrigerant, wherein the vehicle air conditioning device performs: a cooling operation to release the heat from the refrigerant discharged from the compressor into the exterior heat exchanger, decompress the refrigerant by an expansion part, and absorb the heat in the heat exchanger into the refrigerant;a cooling and dehumidifying operation to release the heat from the refrigerant discharged from the compressor into the radiator and the outdoor heat exchanger, decompress the refrigerant through the expansion part, and absorb the heat in the heat exchanger into the refrigerant; a heating operation to release the heat from the refrigerant discharged from the compressor into the radiator, decompress the refrigerant through the expansion part, and absorb the heat in the outdoor heat exchanger into the refrigerant;and a heating and dehumidifying operation to release the heat from the refrigerant discharged from the compressor into the radiator, decompress a portion of the refrigerant through the expansion part, and absorb the heat into the refrigerant in the heat exchanger, while decompressing a remaining refrigerant through the expansion part, and then absorbing the heat into the refrigerant in the outdoor heat exchanger. The vehicle air conditioning device further comprises: a flow control valve provided in a refrigerant flow passage for allowing the refrigerant to flow into the heat exchanger and configured to regulate an amount of the refrigerant flowing through the refrigerant flow passage; an evaporation temperature detection part configured to detect an evaporation temperature of the refrigerant in the heat exchanger;and a flow control part configured to reduce the amount of refrigerant flowing into the heat exchanger using the flow control valve when the evaporation temperature detected by the evaporation temperature detection part is a predetermined temperature or lower during the heating and dehumidification operation;

[0018] By this measure, it is possible to reduce the amount of refrigerant flowing into the heat exchanger when the evaporation temperature of the refrigerant in the heat exchanger is a predetermined temperature or lower, and therefore to prevent frost from forming on the heat exchanger.

[0019] To achieve the above-described objects, an exemplary vehicle air conditioning device not belonging to the invention includes: a compressor configured to compress and discharge a refrigerant; a radiator provided in a vehicle interior and configured to release heat from the refrigerant; a heat exchanger provided in the vehicle interior and configured to absorb the heat in the refrigerant; and an exterior heat exchanger provided outside the vehicle interior and configured to release the heat from the refrigerant or absorb the heat into the refrigerant, wherein the vehicle air conditioning device performs: a cooling operation to release the heat from the refrigerant discharged from the compressor into the exterior heat exchanger, decompress the refrigerant by an expansion part, and absorb the heat in the heat exchanger into the refrigerant;a cooling and dehumidifying operation to release the heat from the refrigerant discharged from the compressor into the radiator and the outdoor heat exchanger, decompress the refrigerant through the expansion part, and absorb the heat in the heat exchanger into the refrigerant; a heating operation to release the heat from the refrigerant discharged from the compressor into the radiator, decompress the refrigerant through the expansion part, and absorb the heat in the outdoor heat exchanger into the refrigerant;and a heating and dehumidifying operation to release the heat from the refrigerant discharged from the compressor into the radiator, decompress a portion of the refrigerant through the expansion part, and absorb the heat into the refrigerant in the heat exchanger while decompressing a remaining refrigerant through the expansion part, and then absorb the heat into the refrigerant in the outdoor heat exchanger. The vehicle air conditioning device further comprises: a bypass flow passage configured to connect between a portion of a refrigerant flow passage connected to an inlet side of the heat exchanger into which the refrigerant flows and a portion of the refrigerant passage connected to an outlet side of the heat exchanger from which the refrigerant flows; a flow control valve configured to be capable of adjusting an amount of refrigerant flowing through the bypass flow passage;an evaporation temperature detection part configured to detect an evaporation temperature of the refrigerant in the heat exchanger; and a refrigerant flow control part configured to increase the amount of refrigerant flowing through the bypass flow passage using the flow adjustment valve when the evaporation temperature detected by the evaporation temperature detection part is a predetermined temperature or lower during the heating and dehumidification operation.

[0020] This measure makes it possible to increase the amount of refrigerant flowing through the bypass flow passage and thus reduce the amount of refrigerant flowing into the heat exchanger. As a result, it is possible to prevent frost from forming on the heat exchanger.

[0021] To achieve the above-described objects, an exemplary vehicle air conditioning device not belonging to the invention includes: a compressor configured to compress and discharge a refrigerant; a radiator provided in a vehicle interior and configured to release heat from the refrigerant; a heat exchanger provided in the vehicle interior and configured to absorb heat into the refrigerant; and an exterior heat exchanger provided outside the vehicle interior and configured to release heat from the refrigerant or absorb heat into the refrigerant, wherein the vehicle air conditioning device performs: a cooling operation to release heat from the refrigerant discharged from the compressor into the exterior heat exchanger, decompress the refrigerant by an expansion part, and absorb heat in the heat exchanger into the refrigerant;a cooling and dehumidifying operation to release the heat from the refrigerant discharged from the compressor into the radiator and the outdoor heat exchanger, decompress the refrigerant through the expansion part, and absorb the heat in the heat exchanger into the refrigerant; a heating operation to release the heat from the refrigerant discharged from the compressor into the radiator, decompress the refrigerant through the expansion part, and absorb the heat in the outdoor heat exchanger into the refrigerant;and a heating and dehumidifying operation to release the heat from the refrigerant discharged from the compressor into the radiator, decompress a portion of the refrigerant by the expansion part, and absorb the heat into the refrigerant in the heat exchanger, while a remaining refrigerant is decompressed by the expansion part and then absorbs the heat into the refrigerant in the outdoor heat exchanger. The vehicle air conditioning device further comprises: a flow control valve provided in a refrigerant flow passage for allowing the refrigerant to flow into the outdoor heat exchanger and configured to regulate an amount of the refrigerant flowing through the refrigerant flow passage; an evaporation temperature detection part configured to detect an evaporation temperature of the refrigerant in the heat exchanger;and a refrigerant flow control part configured to increase the amount of refrigerant flowing into the outdoor heat exchanger using the flow control valve when the evaporation temperature detected by the evaporation temperature detection part is a predetermined temperature or lower during the heating and dehumidification operation;

[0022] By this measure, it is possible to reduce the amount of refrigerant flowing into the heat exchanger when the evaporation temperature of the heat exchanger in the heat exchanger is a predetermined temperature or lower, and therefore to prevent frost from forming on the heat exchanger.

[0023] To achieve the above-described objects, the vehicle air conditioning device according to the present invention includes: a compressor configured to compress and discharge a refrigerant; a radiator provided in a vehicle interior and configured to release heat from the refrigerant; a heat exchanger provided in the vehicle interior and configured to absorb the heat in the refrigerant; and an exterior heat exchanger provided outside the vehicle interior and configured to release the heat from the refrigerant or absorb the heat into the refrigerant, wherein the vehicle air conditioning device performs: a cooling operation to release the heat from the refrigerant discharged from the compressor into the exterior heat exchanger, decompress the refrigerant by an expansion part, and absorb the heat in the heat exchanger into the refrigerant;a cooling and dehumidifying operation to release the heat from the refrigerant discharged from the compressor into the radiator and the outdoor heat exchanger, decompress the refrigerant through the expansion part, and absorb the heat in the heat exchanger into the refrigerant; a heating operation to release the heat from the refrigerant discharged from the compressor into the radiator, decompress the refrigerant through the expansion part, and absorb the heat in the outdoor heat exchanger into the refrigerant;and a heating and dehumidifying operation to release the heat from the refrigerant discharged from the compressor into the radiator, decompress a portion of the refrigerant by the expansion part, and absorb the heat into the refrigerant in the heat exchanger, while decompressing a remaining refrigerant by the expansion part and then absorbing the heat into the refrigerant in the outdoor heat exchanger. The vehicle air conditioning device further comprises: an on-off valve provided in a refrigerant flow passage for allowing the refrigerant to flow into the outdoor heat exchanger and configured to be capable of opening and closing the refrigerant flow passage; a cooled-air temperature sensor configured to detect a temperature of air cooled in the heat exchanger;and a refrigerant flow restriction part configured to restrict the refrigerant from flowing into the heat exchanger using the on-off valve when the evaporation temperature detected by the cooled air temperature sensor is a predetermined temperature or lower during the heating and dehumidifying operation;

[0024] By this measure, it is possible to prevent the refrigerant from absorbing heat in the outdoor heat exchanger, but to allow the refrigerant to absorb heat only in the heat exchanger when the evaporation temperature of the heat-absorbing refrigerant is a predetermined temperature or lower. Therefore, it is possible to prevent the evaporation temperature of the refrigerant in the heat exchanger from decreasing, and consequently, to prevent frost from forming on the heat exchanger.

[0025] To achieve the above-described objects, an exemplary vehicle air conditioning device not belonging to the invention includes: a compressor configured to compress and discharge a refrigerant; a radiator provided in a vehicle interior and configured to release heat from the refrigerant; a heat exchanger provided in the vehicle interior and configured to absorb the heat in the refrigerant; and an exterior heat exchanger provided outside the vehicle interior and configured to release the heat from the refrigerant or absorb the heat into the refrigerant, wherein the vehicle air conditioning device performs: a cooling operation to release the heat from the refrigerant discharged from the compressor into the exterior heat exchanger, decompress the refrigerant by an expansion part, and absorb the heat in the heat exchanger into the refrigerant;a cooling and dehumidifying operation to release the heat from the refrigerant discharged from the compressor into the radiator and the outdoor heat exchanger, decompress the refrigerant through the expansion part, and absorb the heat into the refrigerant in the heat exchanger; a heating operation to release the heat from the refrigerant discharged from the compressor into the radiator, decompress the refrigerant through the expansion part, and absorb the heat into the refrigerant in the outdoor heat exchanger;and a heating and dehumidifying operation to release the heat from the refrigerant discharged from the compressor into the radiator, decompress the refrigerant through the expansion part, and absorb the heat in the heat exchanger and the outdoor heat exchanger, or at least in the heat exchanger, into the refrigerant. The vehicle air conditioning device further comprises: an ambient condition detection part configured to detect at least one of ambient conditions including an outside air temperature, an indoor air temperature, an indoor air humidity, and a degree of solar radiation; a fogging detection part configured to detect whether conditions are met for window glasses of the vehicle interior to fog;and a mode switching part configured to be capable of switching a switching mode among a first switching mode, a second switching mode, and a third switching mode, wherein: the first switching mode switches an operation between the heating operation, the heating and dehumidifying operation, the cooling operation, and the cooling and dehumidifying operation based on the ambient conditions detected by the ambient condition detection part; the second switching mode switches the operation between the heating operation, the heating and dehumidifying operation, the cooling operation, and the cooling and dehumidifying operation, and performs the heating and dehumidifying operation only when the fogging detection part determines that the conditions for fogging the window glasses are met;and the third switching mode that switches the operation between the heating operation, the cooling operation, and the cooling and dehumidifying operation based on the ambient conditions detected by the ambient condition detecting part;

[0026] This measure makes it possible to switch between the first switching mode, the second switching mode, and the third switching mode, each with different energy consumption. Therefore, a passenger can choose between the first, second, and third switching modes.

[0027] To achieve the above-described objects, an exemplary vehicle air conditioning device not belonging to the invention includes: a compressor configured to compress and discharge a refrigerant; a radiator provided in a vehicle interior and configured to release heat from the refrigerant; a heat exchanger provided in the vehicle interior and configured to absorb the heat into the refrigerant; and an exterior heat exchanger provided outside the vehicle interior and configured to release the heat from the refrigerant or absorb the heat into the refrigerant, wherein the vehicle air conditioning device performs: a heating operation to release the heat from the refrigerant discharged from the compressor into the radiator and absorb the heat in the exterior heat exchanger into the refrigerant;and a heating and dehumidifying operation to release the heat from the refrigerant discharged from the compressor into the radiator and absorb the heat in the heat exchanger into a portion of the refrigerant, while absorbing the heat in the outdoor heat exchanger into the remaining refrigerant. The vehicle air conditioning device further comprises: an expansion valve provided in a refrigerant flow passage for allowing the refrigerant to flow into the outdoor heat exchanger, the expansion valve having an adjustable opening; a heat exchanger temperature sensor configured to detect an evaporation temperature of the refrigerant in the heat exchanger;a target superheat setting part configured to set a predetermined value as a target superheat during the heating operation, and to set a value calculated based on the evaporation temperature detected by the heat exchanger temperature sensor and a target temperature of the heat exchanger as the target superheat during the heating and dehumidification operation; a superheat calculation part configured to calculate a superheat of the refrigerant flowing out of the outdoor heat exchanger; and a valve opening control part configured to control the opening of the expansion valve based on the target superheat set by the target superheat setting part and the superheat calculated by the superheat calculation part.

[0028] By this measure, it is possible to maintain the optimal superheat of the refrigerant flowing out of the outdoor heat exchanger and therefore it is possible to optimize the amount of heat to be absorbed into the refrigerant in the outdoor heat exchanger. Advantageous effect of the invention

[0029] According to the present invention, it is possible to prevent frost from being formed on the heat exchanger and therefore to maintain the dehumidifying ability during a heating and dehumidifying operation in a cool environment.

[0030] According to the present invention, a passenger of the vehicle can switch the switching mode between the first switching mode, the second switching mode, and the third switching mode. Therefore, by selecting the second switching mode or the third switching mode, which has lower power consumption than the first switching mode, it is possible to prevent the driving range of the vehicle from decreasing while an air-conditioning operation in the vehicle interior continues.

[0031] According to the present invention, it is possible to acquire an optimal amount of heat absorbed into the refrigerant in the outdoor heat exchanger, and therefore to maintain the temperature and humidity of the vehicle interior in a good state. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic view showing a vehicle air conditioning device according to Embodiment 1 of the present invention; Fig. 2 is a block diagram showing a control system; Fig. 3 is a schematic view showing the vehicle air conditioning device performing a cooling operation and a cooling and dehumidifying operation; Fig. 4 is a schematic view showing the vehicle air conditioning device performing a heating operation; Fig. 5 is a schematic view showing the vehicle air conditioning device performing a heating and dehumidifying operation; Fig. 6 is a schematic view showing a vehicle air conditioning device performing a defrosting operation; Fig. 7 is a flowchart showing a process to control the temperature of the heat exchanger; Fig. 8 is a drawing showing the relationship between the opening and closing of a solenoid valve and the temperature of the heat exchanger; Fig. 9 is a schematic view showing the vehicle air conditioning device according to Embodiment 2 of the present invention; Fig. 10 is a block diagram showing a control system; Fig. 11 is a flowchart showing a process to control the temperature of the heat exchanger; Fig. 12 is a drawing showing the relationship between the opening and closing of the solenoid valve and the temperature of the heat exchanger; Fig. 13 is a schematic view showing the vehicle air conditioning device according to Embodiment 3 of the present invention; Fig. 14 is a block diagram showing a control system; Fig. 15 is a flowchart showing a process for controlling the temperature of the heat exchanger; Fig. 16 is a flowchart showing a process for controlling the temperature of the heat exchanger according to Embodiment 4 of the present invention; Fig. 17 is a drawing showing the relationship between the opening and closing of the solenoid valve and the temperature of the heat exchanger; Fig. 18 is a schematic view showing the vehicle air conditioning device according to Embodiment 5 of the present invention; Fig. 19 is a block diagram showing a control system; Fig. 20 is a schematic view showing the vehicle air conditioning device performing a cooling operation and a cooling and dehumidifying operation; Fig. 21 is a schematic view showing the vehicle air conditioning device performing a heating operation; Fig. 22 is a schematic view showing the vehicle air conditioning device performing a first heating and dehumidifying operation; Fig. 23 is a schematic view showing the vehicle air conditioning device performing a second heating and dehumidifying operation; Fig. 24 is a schematic view showing the vehicle air conditioning device performing a defrosting operation; Fig. 25 is a flowchart showing an operation switching control process in a normal mode; Fig. 26 is a flowchart showing an operation switching control process in the first power saving mode; Fig. 27 is a flowchart showing an operation switching control process in the second power saving mode; Fig. 28 is a schematic view showing the vehicle air conditioning device according to Embodiment 6 of the present invention; Fig. 29 is a block diagram showing a control system; Fig. 30 is a schematic view showing the vehicle air conditioning device performing a cooling operation and a cooling and dehumidifying operation; Fig. 31 is a schematic view showing the vehicle air conditioning device performing a heating operation; Fig. 32 is a schematic view showing the vehicle air conditioning device performing a heating and dehumidifying operation; Fig. 33 is a schematic view showing the vehicle air conditioning device performing a defrosting operation; Fig. 34 is a flowchart showing an overheat control process; and Fig. 35 is a flowchart showing an overheat control process according to Embodiment 7 of the present invention. DESCRIPTION OF THE EMBODIMENTS

[0032] Fig. 1 to Fig. 8 shows Embodiment 1 of the present invention.

[0033] As in Fig. 1, the vehicle air conditioning device according to the present invention includes an air conditioning unit 10 provided in the vehicle interior and a refrigerant circuit 20 formed across the vehicle interior and the exterior.

[0034] The air conditioning unit 10 includes an airflow passage 11 that allows air to be supplied to the vehicle interior to pass through; an outside air inlet 11a and an inside air inlet 11b are provided on the first end side of the airflow passage 11. The outside air inlet 11a is configured to allow outside air to flow into the airflow passage 11, and the inside air inlet 11b is configured to allow inside air to flow into the airflow passage 11. Meanwhile, a foot outlet 11c, a ventilation outlet 11d, and a defroster outlet 11e are provided on the second end side of the airflow passage 11. The foot outlet 11c is configured to allow the air flowing through the airflow passage 11 to be blown to the feet of the passengers in the vehicle.The ventilation outlet 11d is configured to allow the air flowing through the airflow passage 11 to be blown toward the upper bodies of the passengers in the vehicle. The defroster outlet 11e is configured to allow the air flowing through the airflow passage 11 to be blown toward the inner surface of the front window.

[0035] An interior fan 12, such as a sirocco fan, configured to allow air to flow through the air flow passage 11 from end to end, is provided on the first end side of the air flow passage 11. This interior fan 12 is driven by the electric motor 12a.

[0036] Also, on the first end side of the airflow passage 11, there is an inlet switching damper 13 configured to open one of the outside air inlet 11a and the inside air inlet 11b and close the other. This inlet switching damper 13 is driven by the electric motor 13a. Meanwhile, when the inlet switching damper 13 closes the outside air inlet 11a and opens the inside air inlet 11b, the operation mode is switched to an inside air circulation mode in which air flows from the inside air inlet 11b into the airflow passage 11. Meanwhile, when the inlet switching damper 13 closes the inside air inlet 11b and opens the outside air inlet 11a, the operation mode is switched to an inside air circulation mode in which air flows from the inside air inlet 11b into the airflow passage 11.In addition, when the inlet switching damper 13 is placed between the outside air inlet 11a and the indoor air inlet 11b, and the outside air inlet 11a and the indoor air inlet 11b open, the operation mode is switched to a two-way operation mode in which the air flows into the air flow passage 11 from both the outside air inlet 11a and the indoor air inlet 11b according to the opening ratio of the outside air inlet 11a and the indoor air inlet 11b.

[0037] Outlet switching dampers 13b, 13c, and 13d, configured to open and close the foot outlet 11c, the ventilation outlet 11d, and the defroster outlet 11e, are provided on the second side of the air flow passage 11, respectively, in the foot outlet 11c, the ventilation outlet 11d, and the defroster outlet 11e. These outlet switching dampers 13b, 13c, and 13d are configured to move with each other through a linkage (not shown) and are opened and closed by the electric motor 13e. Here, when the outlet switching dampers 13b, 13c, and 13d open the foot outlet 11c, close the ventilation outlet 11d, and slightly open the defroster outlet 11e, most of the air flowing through the air flow passage 11 is discharged from the foot outlet 11c, and the remaining air is discharged from the defroster outlet 11e. This operation mode is referred to as the "foot operation mode."Meanwhile, when the outlet switching dampers 13b, 13c, and 13d close the foot outlet 11c and the defroster outlet 11e and open the ventilation outlet 11d, all the air flowing through the air flow passage 11 is blown out of the ventilation outlet 11d. This operation mode is referred to as "ventilation mode." In addition, when the outlet switching dampers 13b, 13c, and 13d open the foot outlet 11c and the ventilation outlet 11d and close the defroster outlet 11e, the air flowing through the air flow passage 11 is blown out of the foot outlet 11c and the ventilation outlet 11d. This operation mode is referred to as "two-level mode." Furthermore, when the outlet switching dampers 13b, 13c, and 13d close the foot outlet 11c and the ventilation outlet 11d and open the defroster outlet 11e, the air flowing through the air flow passage 11 is blown out of the defroster outlet 11e. This operation mode is referred to as "defroster mode."Furthermore, when the outlet switching dampers 13b, 13c, and 13d close the ventilation outlet 11d and open the foot outlet 11c and the defroster outlet 11e, the air flowing through the air flow passage 11 is blown out from the foot outlet 11c and the defroster outlet 11e. This operation mode is referred to as "defroster foot mode." Here, in the two-level operation mode, the air flow passage 11, the foot outlet 11c, the ventilation outlet 11d, and a heat exchanger and a radiator described later are arranged and configured so that the temperature of the air blown out from the foot outlet 11c is higher than the temperature of the air blown out from the ventilation outlet 11d.

[0038] A heat exchanger 14 is provided in the air flow passage 11 downstream of the air flow from the indoor fan 12. The heat exchanger 14 is configured to cool and dehumidify the air flowing through the air flow passage 11. Additionally, a radiator 15 is provided in the air flow passage 11 downstream of the air flow from the heat exchanger 14. The radiator 15 is configured to heat the air flowing through the air flow passage 11. The heat exchanger 14 and the radiator 15 are heat exchangers, each formed by fins and tubes, and configured to perform heat exchange between the refrigerant flowing through the refrigerant circuit 20 and the air flowing through the air flow passage 11.

[0039] An air mixing damper 16 is provided in the air flow passage 11 between the heat exchanger 14 and the radiator 15, and is configured to control the percentage of air to be heated flowing through the air flow passage 11. The air mixing damper 16 is driven by the electric motor 16a.

[0040] When the air mixing damper 16 is arranged upstream of the radiator 15 in the air flow passage 11, the percentage of air subjected to heat exchange in the radiator 15 is reduced. Meanwhile, when the air mixing damper 16 is moved to a position other than the radiator 15 in the air flow passage 11, the percentage of air subjected to heat exchange is increased. In the air flow passage 11, when the air mixing damper 16 closes the upstream side of the radiator 15 and opens the portion other than the radiator 15, the opening is 0%, and otherwise, when the air mixing damper 16 opens the upstream side of the radiator 15 and closes the portion other than the radiator 15, the opening is 100%.

[0041] The refrigerant circuit 20 includes: the heat exchanger 14; the radiator 15; a compressor 21 configured to compress refrigerant; an outdoor heat exchanger 22 configured to perform heat exchange between the refrigerant and the outside air; an indoor heat exchanger 23 configured to perform heat exchange between the refrigerant flowing out of the radiator 15 or through the outdoor heat exchanger 22 and the refrigerant flowing out of the heat exchanger 14; a three-way valve 24 configured to switch the passage of the refrigerant; first to fourth solenoid valves 25a to 25d; first and second check valves 26a and 26b; first and second expansion valves 27a and 27b configured to decompress the flowing refrigerant; a collection tank 28 configured to accumulate additional refrigerant;and an accumulator 29 configured to separate refrigerant vapor from refrigerant liquid to prevent refrigerant liquid from being sucked into the compressor 21. These components are connected by a copper pipe or an aluminum pipe. The compressor 21 and the outdoor heat exchanger 22 are arranged outside the vehicle interior. The compressor 21 is driven by the electric motor 21a. The outdoor heat exchanger 22 is provided with an outdoor fan 30 configured to perform heat exchange between the outside air and the refrigerant when the vehicle is stopped. The outdoor fan 30 is driven by the electric motor 30a.

[0042] To be more specific, an inlet side of the radiator 15 into which the refrigerant flows is connected to the discharge side of the compressor 21 from which the refrigerant is discharged, to form the refrigerant flow passage 20a. In addition, the inlet side of the radiator 15 into which the refrigerant flows is connected to the outlet side of the heat exchanger 15 from which the refrigerant is discharged, thereby forming the refrigerant flow passage 20b. The three-way valve 24 is provided in the refrigerant flow passage 20b. One side of the three-way valve 24 from which the refrigerant is discharged and the other side from which the refrigerant is discharged are parallel to each other and are connected to the inlet side of the outdoor heat exchanger 22 into which the refrigerant flows, thereby forming the refrigerant flow passages 20c and 20d.The header tank 28, the first expansion valve 27a, and the first check valve 26a are provided in the refrigerant flow passage 20d in order from the upstream of the refrigerant flow. The suction side of the compressor 21, into which the refrigerant is sucked, and the part of the refrigerant flow passage 20d between the three-way valve 24 and the header tank 28 are connected in parallel with the outlet side of the outdoor heat exchanger 22, from which the refrigerant is discharged, thereby forming the refrigerant flow passages 20e and 20f. The first solenoid valve 25a and the accumulator 29 are provided in the refrigerant flow passage 20e in order from the upstream of the refrigerant flow. The second solenoid valve 25b and the second check valve 26b are provided in the refrigerant flow passage 20f in the order from the upstream of the flow of the refrigerant.The inlet side of the indoor heat exchanger 23, into which a high-pressure refrigerant flows, is connected to the part of the refrigerant flow passage 20d between the header tank 28 and the first expansion valve 27a, thereby forming the refrigerant flow passage 20g. The third solenoid valve 25c is provided in the refrigerant flow passage 20g. The inlet side of the heat exchanger 14, into which the refrigerant flows, is connected to the outlet side of the indoor heat exchanger 23, from which the high-pressure refrigerant is discharged, thereby forming the refrigerant flow passage 20h. The second expansion valve 27b is provided in the refrigerant flow passage 20h. The inlet side of the indoor heat exchanger 23 into which a low-pressure refrigerant flows is connected to the outlet side of the heat exchanger 14 from which the refrigerant is discharged, thereby forming the refrigerant flow passage 20i.The portion of the refrigerant flow passage 20e between the first solenoid valve 25a and the accumulator 29 is connected to the outlet side of the indoor heat exchanger 23, from which the low-pressure refrigerant is discharged, thereby providing the refrigerant flow passage 20j. The inlet side of the outdoor heat exchanger 22, into which the refrigerant flows, is connected to the refrigerant flow passage 20a, thereby providing the refrigerant flow passage 20k. The fourth solenoid valve 25d is provided in the refrigerant flow passage 20k.

[0043] In addition, the vehicle air conditioning device also includes a control device 40 that controls the temperature and humidity of the vehicle interior to be the preset temperature and humidity.

[0044] The control device 40 includes a CPU, a ROM, and a RAM. In the control device, the CPU, upon receiving an input signal from a device connected to the input side, reads the program stored in the ROM according to the input signal, stores the state detected by the input signal in the RAM, and transmits an output signal to a device connected to the output side.

[0045] As in Fig. 2, an electric motor 12a for driving the indoor fan 12; an electric motor 13a for driving the inlet switching damper 13; an electric motor 13e for driving the outlet switching dampers 13b, 13c, and 13d; an electric motor 16a for driving the air mixing damper 16; an electric motor 21a for driving the compressor 21; the three-way valve 24; the first to fourth solenoid valves 25a to 25d; and an electric motor 30a for driving the outdoor fan 30 are connected to the output side of the control device 40.

[0046] As in Fig. 2 are an outside air temperature sensor 41 configured to detect a temperature Tam outside the vehicle interior; an inside air temperature sensor 42 configured to detect an inside air temperature Tr; an inlet temperature sensor 43 configured to detect a temperature Ti of the air flowing into the air flow passage 11; a cooled air temperature sensor 44 configured to detect a temperature Te of the air cooled in the heat exchanger 14; a heated air temperature sensor 45 configured to detect a temperature Tc of the air heated in the radiator 15; an inside air humidity sensor 46 configured to detect an inside air humidity Rh; a refrigerant temperature sensor 47 configured to detect a temperature Thex of the refrigerant after heat exchange in the outside heat exchanger 22;a solar irradiation sensor 48, such as a photosensor, configured to detect a solar irradiation level Ts; a speed sensor 49 configured to detect a speed V of the vehicle; and an operating part 50 configured to set operation modes regarding the target setting temperature Tset and switching of the operation, connected to the input side of the control device 40.

[0047] The vehicle air conditioning system, which has the configuration described above, performs a cooling operation, a cooling and dehumidifying operation, a heating operation, a heating and dehumidifying operation, and a defrosting operation. Each operation will now be explained.

[0048] First, the cooling operation is explained. In the refrigerant circuit 20, the flow passage of the three-way valve 24 is set to the refrigerant flow passage 20c side; the second and third solenoid valves and 25c open and the first and fourth solenoid valves 25a and 25d are closed; and the compressor 21 is operated.

[0049] This measure, as in Fig. 3, the refrigerant discharged from the compressor 21 passes in this order through: the refrigerant flow passage 20a; the radiator 15; the refrigerant flow passages 20d and 20c; the outdoor heat exchanger 22; the refrigerant flow passages 20f, 20d, and 20g; the high-pressure side of the indoor heat exchanger 23; the refrigerant flow passage 20h; the heat exchanger 14; the refrigerant flow passage 20i; the low-pressure side of the indoor heat exchanger 23; and the refrigerant flow passages 20j and 20e, and is sucked into the compressor 21. The refrigerant flowing through the refrigerant circuit 20 releases the heat in the outdoor heat exchanger 22 and absorbs the heat in the heat exchanger 14. When the air mixing damper 16 is opened during a cooling and dehumidification operation, the refrigerant also releases the heat in the radiator 15.

[0050] In this case, the interior fan 12 in the air conditioning unit 10 is operated during the cooling operation to force air through the air flow passage 11, and the air undergoes heat exchange with the refrigerant in the heat exchanger 14 and is cooled. The temperature of the cooled air becomes the target air blowing temperature TAO of the air to be blown out from the outlets 11c, 11d, and 11e to adjust the temperature of the vehicle interior to a predetermined temperature. Then, the air at the temperature TAO is blown into the vehicle interior.

[0051] Meanwhile, during the cooling and dehumidification operation, the interior fan 12 in the air conditioning unit 10 is operated to flow the air through the air flow passage 11. The air undergoes heat exchange with the refrigerant that absorbs heat in the heat exchanger 14, and is thus cooled and dehumidified. The air dehumidified in the heat exchanger 14 undergoes heat exchange with the refrigerant that releases heat in the radiator 15, and is thus warmed. As a result, the air is blown into the vehicle interior at the target air blowing temperature TAO.

[0052] During a heating operation, in the refrigerant circuit 20, the flow passage of the three-way valve 24 is set to the side of the refrigerant flow passage 20d; the first solenoid valve 25a is opened and the second to fourth solenoid valves 25b to 25d are closed; and the compressor 21 is operated. By this measure, as shown in Fig. As shown in Figure 4, the refrigerant discharged from the compressor 21 passes in this order through: 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 20e, and is sucked into the compressor 21. The water flowing through the refrigerant circuit 20 releases the heat in the radiator 15 and absorbs the heat in the outdoor heat exchanger 22.

[0053] In this case, in the air conditioning unit 10, the interior fan 12 is operated to force the air through the air flow passage 11, and the air does not undergo heat exchange with the refrigerant in the heat exchanger 14, but rather undergoes heat exchange with the refrigerant in the radiator 15 and is therefore heated. As a result, the air is blown into the vehicle interior at the target air blowing temperature TAO.

[0054] Next, the heating and dehumidifying operation is explained. In the refrigerant circuit 20, the flow passage of the three-way valve 24 is set to the refrigerant flow passage 20d side; the first and third solenoid valves 25a and 25c open, and the second and fourth solenoid valves 25b and 25d are closed; and the compressor 21 is operated. By this measure, as shown in Fig. 5, the refrigerant discharged from the compressor 21 passes through, in this order: the refrigerant flow passage 20a; the radiator 15; and the refrigerant flow passages 20b and 20d. Part of the refrigerant flowing through the refrigerant flow passage 20d passes through, in this order: the outdoor heat exchanger 22; and the refrigerant flow passage 20e, and is sucked into the compressor 21. Meanwhile, the remaining refrigerant flowing through the refrigerant flow passage 20d passes through, in this order: the refrigerant flow passage 20g; the high-pressure side of the indoor heat exchanger 23; the refrigerant flow passage 20h; the heat exchanger 14; the refrigerant flow passage 20i; the low-pressure side of the indoor heat exchanger 23; and the refrigerant flow passages 20j and 20e, and is sucked into the compressor 21.The refrigerant flowing through the refrigerant circuit 20 releases the heat in the radiator 15 and absorbs the heat in the heat exchanger 14 and the outdoor heat exchanger 22.

[0055] In this case, in the air conditioning unit 10, the interior fan 12 is operated to force air through the airflow passage 11, and the flowing air undergoes heat exchange with the refrigerant in the heat exchanger 14 and is thus cooled and dehumidified. All or part of the air dehumidified in the heat exchanger 14 undergoes heat exchange with the refrigerant in the radiator 15 and is heated. As a result, the air is blown into the vehicle interior at the target air blowing temperature TAO.

[0056] Next, the defrosting operation is explained. In the refrigerant circuit 20, the flow passage of the three-way valve 24 is set to the side of the refrigerant flow passage 20d; the first and fourth solenoid valves 25a and 25d open, and the second and third solenoid valves 25b and 25c are closed; and the compressor 21 is operated. By this measure, as shown in Fig. As shown in Figure 6, a portion of the refrigerant discharged from the compressor 21 passes through the refrigerant flow passage 20a, the radiator 15, and the refrigerant flow passages 20b and 20d, in this order, and flows into the outdoor heat exchanger 22. Meanwhile, the remaining 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 from 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 releases the heat in the radiator 15 and, at this time, absorbs the heat in the outdoor heat exchanger 22.

[0057] In this case, in the air conditioning unit 10, the interior fan 12 is operated to flow the air through the air flow passage 11. The flowing air does not undergo heat exchange with the refrigerant in the heat exchanger 14, but undergoes heat exchange with the refrigerant that releases heat in the radiator 15, and is therefore warmed up and then blown to the vehicle interior.

[0058] While the automatic switch of the operating part 50 is turned on, the control device 40 executes an operation switching control process to switch the operation between the cooling operation, the cooling and dehumidifying operation, the heating operation, the heating and dehumidifying operation, and the defrosting operation based on indoor and outdoor environmental conditions such as temperature.

[0059] In each operation switched by the operation switching control process, the control device 40 switches the switching operation mode between the foot operation mode, the ventilation operation mode, and the two-level operation mode according to the target air blowing temperature TAO. To be more specific, the control device 40 sets the foot operation mode when the target air blowing temperature TAO is high, e.g., 40 degrees Celsius. Meanwhile, the control device 40 sets the ventilation operation mode when the target air blowing temperature TAO is low, e.g., lower than 25 degrees Celsius. Moreover, the control device 40 sets the two-level operation mode when the target air blowing temperature TAO is the temperature between the temperature for the foot operation mode and the temperature for the ventilation operation mode.

[0060] The control device 40 switches the operation mode of the outlets 11c, 11d and 11e using the outlet switching dampers 13b, 13c and 13d, and controls the opening of the air mixing damper 16 to adjust the temperature of the air blown from the outlets 11c, 11d and 11e to the target air blowing temperature TAO.

[0061] Here, when the outside air temperature Tam is low (e.g., 10 degrees Celsius or lower), the evaporation temperature of the refrigerant in the outdoor heat exchanger 22 is low (e.g., 5 to 10 degrees Celsius). In this case, the evaporation temperature of the refrigerant in the heat exchanger 14 is also low (e.g., 0 to 5 degrees Celsius), and therefore, frost is likely to form on the heat exchanger 14.

[0062] In order to prevent frost from forming on the heat exchanger 14 during the heating and dehumidification operation, the control device 40 performs a process to control the temperature of the heat exchanger. Now, with reference to the Fig. The flowchart shown in Figure 7 explains the operation of the control device 40 for this process. (Step S1)

[0063] In step S1, the CPU determines whether the outside air temperature Tam is a predetermined temperature T1 (e.g., 10 degrees Celsius) or lower. If it is determined that the temperature Tam is the predetermined temperature T1 or lower, the CPU proceeds to step S4. Otherwise, if it is determined that the temperature Tam is higher than the predetermined temperature T1, the CPU proceeds to step S2. (Step S2)

[0064] In step S2, the CPU determines whether or not the temperature Thex of the refrigerant flowing out of the outdoor heat exchanger 22 is a predetermined temperature T2 (e.g., 5 to 10 degrees Celsius) or lower. If it is determined that the temperature Thex is the predetermined temperature T2 or lower, the CPU proceeds to step S4. Otherwise, if it is determined that the temperature Thex is higher than the predetermined temperature T2, the CPU proceeds to step S3. (Step S3)

[0065] In step S3, the CPU determines whether a temperature Te of the heat exchanger 14 is equal to or lower than a temperature (Tet-α) calculated by subtracting a predetermined temperature α from a target temperature Tet of the heat exchanger 14. If it is determined that the temperature Te is Tet-α or lower, the CPU proceeds to step S4. Otherwise, if it is determined that the temperature Te is higher than Tet-α, the CPU ends the heat exchanger temperature control process. Here, the target temperature Tet is the condensation point temperature of air at absolute humidity for preventing window glasses of the vehicle interior from fogging, and it is calculated based on the outside air temperature Tam and the inside air temperature Tr. (Step S4)

[0066] In the case where the temperature Tam is the temperature T1 or lower predetermined in step S1, in the case where the temperature Thex is the temperature T2 or lower predetermined in step S2, or in the case where the temperature Te is Tet-α or lower in step S3, the CPU controls to switch the opening and closing of the third solenoid valve 25c. To be more specific, the third solenoid valve 25c is closed when, as shown in Fig. 8, the temperature Te of the heat exchanger 14 is lowered from a temperature higher than the target temperature Tet of the heat exchanger 14 to a temperature (Tet-β) obtained by subtracting a predetermined temperature β from the target temperature Tet. Otherwise, the third solenoid valve 25c is open when the temperature Te of the heat exchanger 14 is raised from a temperature lower than Tet-β to the target temperature Tet.

[0067] In this way, with the vehicle air conditioning device according to the present embodiment, during the heating and dehumidifying operation, the third solenoid valve 25c is closed in the case where the outside air temperature Tam is the predetermined temperature T1 or lower while the temperature Te detected by the cooled air temperature sensor 44 is Tet-β or lower, or in the case where the temperature Thex of the refrigerant flowing out of the outdoor heat exchanger 22 is the predetermined temperature T2 or lower. By this measure, in a case where frost is likely to be formed on the heat exchanger 14 during the heating and dehumidifying operation, the flow of the refrigerant into the heat exchanger 14 is stopped. Therefore, it is possible to prevent frost from forming on the heat exchanger 14.

[0068] Here, in Embodiment 1, as a means for stopping the flow of refrigerant into the heat exchanger 14, a configuration in which the third solenoid valve 25c provided in the refrigerant flow passage 20g is closed was described. However, this is by no means limiting. Another configuration is possible in which the flow of refrigerant into the heat exchanger 14 is stopped using, for example, an electronic expansion valve with an adjustable orifice as the second expansion valve 27b provided in the refrigerant flow passage 20h connected to the inlet side of the heat exchanger 14 into which the refrigerant flows.

[0069] In addition, in Embodiment 1, a configuration in which the flow of refrigerant into the heat exchanger 14 is blocked by closing the third solenoid valve 25c was described as an example. However, another configuration is possible in which an amount of refrigerant flowing into the heat exchanger 14 is reduced to prevent frost from forming on the heat exchanger 14.

[0070] Fig. 9 to 12 show Embodiment 2 of the present invention. Here, the same components are assigned the same reference numerals as in Embodiment 1.

[0071] As in Fig. As shown in Figure 9, the air conditioning device according to the present embodiment has a bypass flow passage 201 provided to connect between the refrigerant flow passage 20i and a part of the refrigerant flow passage 20h on the downstream side of the second expansion valve 27b in the refrigerant flow direction. This bypass flow passage 201 is configured to allow the refrigerant flowing through the refrigerant flow passage 20h to flow into the refrigerant flow passage 20i and bypass the heat exchanger 14. In addition, a bypass solenoid valve 25e is provided in the bypass flow passage 201, which is configured to be capable of opening and closing the refrigerant flow passage. As shown in Fig. 10, the bypass solenoid valve 25e is connected to the output side of the control device 40.

[0072] In the vehicle air conditioning device having the above-described configuration, the control device 40 performs a process during the heating and dehumidifying operation to control the temperature of the heat exchanger 14 in order to prevent frost from forming on the heat exchanger 14 when the outside air temperature Tam is low. Now, the operation of the control device 40 in this process will be described with reference to the Fig. The flowchart shown in Figure 11 is explained. (Step S11)

[0073] In step S11, the CPU determines whether the outside air temperature Tam is the predetermined temperature T1 (e.g., 10 degrees Celsius) or lower. If it is determined that the temperature Tam is the predetermined temperature T1 or lower, the CPU proceeds to step S14. Otherwise, if it is determined that the temperature Tam is higher than the predetermined temperature T1, the CPU proceeds to step S12. (Step S12)

[0074] In step S12, the CPU determines whether the temperature Thex of the refrigerant flowing out of the outdoor heat exchanger 22 is the predetermined temperature T2 (e.g., 5 to 10 degrees Celsius) or lower. If it is determined that the temperature Thex is the predetermined temperature T2 or lower, the CPU proceeds to step S14. Otherwise, if it is determined that the temperature Thex is higher than the predetermined temperature T2, the CPU proceeds to step S13. (Step S13)

[0075] In step S13, the CPU determines whether the temperature Te of the heat exchanger 14 is equal to or lower than the temperature (Tet-α) obtained by subtracting the predetermined temperature α from the target temperature Tet of the heat exchanger 14. If it is determined that the temperature Te is equal to or lower than Tet-α, the CPU advances to step S14. Otherwise, if it is determined that the temperature Te is higher than Tet-α, the CPU terminates the heat exchanger temperature control process. (Step S14)

[0076] In the case where in step S11 the temperature Tam is the predetermined temperature T1 or lower, in the case where in step S12 the temperature Thex is the predetermined temperature T2 or lower, or in the case where in step S13 the temperature Te is Tet-α or lower, the CPU controls to switch the opening and closing of the bypass solenoid valve 25e. To be more specific, the bypass solenoid valve 25e is open when, as shown in Fig. 12, the temperature Te of the heat exchanger 14 is reduced from a temperature higher than the target temperature Tet of the heat exchanger 14 to the temperature (Tet-β) obtained by subtracting the predetermined temperature β from the target temperature Tet. Otherwise, the bypass solenoid valve 25e is closed when the temperature Te of the heat exchanger 14 is increased from a temperature lower than Tet-β to the target temperature Tet.

[0077] In this way, with the vehicle air conditioning device according to the present embodiment, during the heating and dehumidifying operation, while the temperature Te detected by the cooled air temperature sensor 44 is Tet-β or lower, the bypass solenoid valve 25e is opened in the case where the outside air temperature Tam is the predetermined temperature T1 or lower, or in the case where the temperature Thex of the refrigerant flowing out of the outdoor heat exchanger 22 is the predetermined temperature T2 or lower. By this measure, in a case where frost is likely to form on the heat exchanger 14 during the heating and dehumidifying operation, the refrigerant is caused to flow into the bypass flow passage 201 to reduce an amount of refrigerant flowing into the heat exchanger 14. Therefore, it is possible to prevent frost from forming on the heat exchanger 14.

[0078] In addition, the bypass flow passage 201 is provided to connect between the refrigerant flow passage 20i and the part of the refrigerant flow passage 20h on the downstream side of the second expansion valve 27h in the refrigerant flow direction. By this measure, it is possible to allow the refrigerant decompressed in the second expansion valve 27b to flow through the bypass flow passage 201. Therefore, it is possible to reduce the impact at the time the bypass solenoid valve 25e is opened and closed.

[0079] Here, in Embodiments 1 and 2, the configuration in which, when frost is likely to form on the heat exchanger 14, control is performed by switching between the opening and closing of the third solenoid valve 25c or the bypass solenoid valve 25e to allow or stop the flow of refrigerant through the refrigerant flow passages 20g and 20h has been described. However, this is by no means limiting. Another configuration is possible in which, for example, a valve with an adjustable orifice is used instead of the third solenoid valve 25c and the bypass solenoid valve 25e to control an amount of refrigerant flowing through the refrigerant flow passages 20g and 20k. By this measure, it is possible to prevent frost from forming on the heat exchanger 14 in the same manner as in Embodiments 1 and 2.Another configuration is also possible in which a solenoid valve is applied as a valve with the adjustable opening to change the time ratio in which the valve is opened at a predetermined time to change the flow rate of the refrigerant.

[0080] Fig. 13 to 15 show Embodiment 3 of the present invention. Here, the same components are assigned the same reference numerals as in the above-described embodiments.

[0081] In the vehicle air conditioning device according to the present embodiment, an electronic expansion valve 27c with the adjustable opening is used in the refrigerant circuit 20 of Embodiment 1 instead of the first expansion valve. In addition, the outdoor heat exchanger 22 is provided with a pressure sensor 51 for detecting a pressure P of the refrigerant in the outdoor heat exchanger 22. As shown in Fig. As shown in Fig. 14, the electronic expansion valve 27c and the pressure sensor 51 are connected to the output side and the input side of the control device 40, respectively.

[0082] In the vehicle air conditioning device having the above-described configuration, the control device 40 performs a process during the heating and dehumidifying operation to control the temperature of the heat exchanger 14 to prevent frost from forming on the heat exchanger 14 when the outside air temperature Tam is low. Now, the operation of the control device 40 in this process will be described with reference to the Fig. The flowchart shown in Figure 15 is explained. (Step S21)

[0083] In step S21, the CPU calculates a temporary target superheat SHtp based on the outside air temperature Tam and the target temperature Tet of the heat exchanger 14 and advances to step S22. (Step S22)

[0084] In step S22, the CPU calculates a superheat correction amount H based on the temperature Te and the target temperature Tet of the heat exchanger 14. To be more specific, the CPU determines whether the temperature Te of the heat exchanger 14 is equal to or lower than a temperature (Tet-γ) obtained by subtracting a predetermined temperature γ from the target temperature Tet. If the temperature Te is Tet-γ or lower, the CPU determines a correction amount H (H<0) to decrease the target superheat SHt. Otherwise, if the temperature Te is higher than Tet-γ, the CPU determines a correction amount H (H>0) to increase the target superheat SHt. (Step S23)

[0085] In step S23, the CPU calculates a target superheat SHt by adding the correction amount H to the temporary target superheat SHtp. (Step S24)

[0086] In step S24, the CPU calculates the opening of the electronic expansion valve 27c based on the target superheat SHt and the current superheat SH, and controls the electronic expansion valve 27c to open to the calculated value. Here, the current superheat SH is calculated based on 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.

[0087] In this way, with the vehicle air conditioning device according to the present invention, the target superheat SHt is lowered during the heating and dehumidification operation when the temperature Te detected by the cooled air temperature sensor 44 is Tet-γ or lower. By this measure, when frost is likely to form during the heating and dehumidification operation, the electronic expansion valve 27c is controlled to lower the superheat SH, so that the flow rate of the refrigerant flowing through the outdoor heat exchanger 22 is increased to reduce the amount of refrigerant flowing into the heat exchanger 14. As a result, it is possible to prevent frost from forming on the heat exchanger 14.

[0088] Fig. 16 and Fig. 17 shows Embodiment 4 of the present invention. Here, the same components are assigned the same reference numerals as in the above-described embodiments.

[0089] The vehicle air conditioning device according to the present invention has the same configuration as in Embodiment 3, and the electronic expansion valve 27c is opened and closed during a process for controlling the temperature of the heat exchanger. Now, the operation of the control device 40 in this process will be described with reference to the Fig. The flowchart shown in Figure 16 is explained. (Step S31)

[0090] In step S31, the CPU determines whether the outside air temperature Tam is the predetermined temperature T1 (e.g., 10 degrees Celsius) or lower. If it is determined that the temperature Tam is the predetermined temperature T1 or lower, the CPU proceeds to step S34. Otherwise, if it is determined that the temperature Tam is higher than the predetermined temperature T1, the CPU proceeds to step S32. (Step S32)

[0091] In step S32, the CPU determines whether the temperature Thex of the refrigerant flowing out of the outdoor heat exchanger 22 is the predetermined temperature T2 (e.g., 5 to 10 degrees Celsius) or lower. If it is determined that the temperature Thex is the predetermined temperature T2 or lower, the CPU proceeds to step S34. Otherwise, if it is determined that the temperature Thex is higher than the predetermined temperature T2, the CPU proceeds to step S33. (Step S33)

[0092] In step S33, the CPU determines whether the temperature Te of the heat exchanger 14 is equal to or lower than the temperature (Tet-α) calculated by subtracting the predetermined temperature α from the target temperature Tet of the heat exchanger 14. If it is determined that the temperature Te is Tet-α or lower, the CPU advances to step S34. Otherwise, if it is determined that the temperature Te is higher than Tet-α, the CPU terminates the heat exchanger temperature control process. (Step S34)

[0093] In the case where in step S31 the temperature Tam is the predetermined temperature T1 or lower, in the case where in step S32 the temperature Thex is the predetermined temperature T2 or lower, or in the case where in step S33 the temperature Te is Tet-α or lower, the CPU controls the opening and closing of the electronic expansion valve 27c. To be more specific, the electronic expansion valve 27c is closed when, as shown in Fig. 17, the temperature Te of the heat exchanger 14 is lowered from a temperature higher than the set temperature Tet of the heat exchanger 14 to the temperature (Tet-β) obtained by subtracting the predetermined temperature β from the set temperature Tet. Otherwise, the electronic expansion valve 27c is open when the temperature Te of the heat exchanger 14 is raised from a temperature lower than Tet-β to the set temperature Tet.

[0094] In this way, with the vehicle air conditioning system according to the present embodiment, during the heating and dehumidification operation, while the temperature Te detected by the cooled air temperature sensor 44 is Tet-β or lower, the electronic expansion valve 27c is closed in the case where the outside air temperature Tam is the predetermined temperature T1 or lower, or in the case where the temperature Thex of the refrigerant flowing out of the outdoor heat exchanger 22 is the predetermined temperature T2 or lower. By this measure, during the heating and dehumidification operation, when frost is likely to form on the heat exchanger 14, the flow of refrigerant into the outdoor heat exchanger 22 is stopped to prevent the refrigerant from absorbing the heat in the outdoor heat exchanger 22 and only allow the refrigerant to absorb the heat in the heat exchanger 14.Therefore, it is possible to prevent the evaporation temperature of the refrigerant in the heat exchanger 14 from being lowered, and hence to prevent frost from being formed on the heat exchanger 14.

[0095] Here, in the present embodiment, a configuration has been described in which the amount of heat obtained by heat exchange between the air flowing through the airflow passage 11 and the refrigerant that releases heat in the radiator 15 is used as the heat source for the heating and dehumidification operation and the cooling and dehumidification operation. In this case, when the amount of heat is insufficient, an auxiliary heat source may be provided. For example, in addition to the radiator 15, an electric heater may be provided in the airflow passage 11 as a heat source that can directly heat the airflow passage 11. In addition, a water heating circuit is formed across the inside and outside of the airflow passage 11 to heat the water flowing through the water heating circuit outside the airflow passage 11 and to release the heat from the heated water into the airflow passage 11.

[0096] Furthermore, a configuration was described in which the three-way valve 24 is used to switch between the refrigerant flow passages 20c and 20d. However, this is by no means limiting. Instead of the three-way valve 24, two solenoid valves can be used to switch between the refrigerant flow passages 20c and 20d.

[0097] Fig. 18 to 27 show Embodiment 5 according to the present invention.

[0098] As in Fig. 18, the vehicle air conditioning device according to the present invention includes the air conditioning unit 10 provided in the vehicle interior and the refrigerant circuit 20 formed across the vehicle interior and the exterior.

[0099] The air conditioning unit 10 includes the airflow passage 11, which allows the air to be supplied to the vehicle interior to pass through. The outside air inlet 11a and the inside air inlet 11b are provided on the first end side of the airflow passage 11. The outside air inlet 11a is configured to allow the outside air to flow into the airflow passage 11, and the inside air inlet 11b is configured to allow the inside air to flow into the airflow passage 11. Meanwhile, the foot outlet 11c, the ventilation outlet 11d, and the defroster outlet 11e are provided on the second end side of the airflow passage 11. The foot outlet 11c is configured to allow the air flowing through the airflow passage 11 to be blown to the feet of the passengers in the vehicle.The ventilation outlet 11d is configured to allow the air flowing through the airflow passage 11 to be blown toward the upper bodies of the passengers in the vehicle. The defroster outlet 11e is configured to allow the air flowing through the airflow passage 11 to be blown toward the inner surface of the front window.

[0100] The indoor fan 12, such as a sirocco fan, configured to allow the air to flow through the air flow passage 11 from end to end, is provided on the first end side of the air flow passage 11.

[0101] This interior fan 12 is driven by the electric motor 12a.

[0102] Also, on the first end side of the airflow passage 11, the inlet switching damper 13 is configured to open one of the outside air inlet 11a and the indoor air inlet 11b and close the other. This inlet switching damper 13 is driven by the electric motor 13a. When the inlet switching damper 13 closes the indoor air inlet 11b and opens the outside air inlet 11a, the operation mode is switched to an outside air supply mode in which the air flows from the outside air inlet 11a into the airflow passage 11. Meanwhile, when the inlet switching damper 13 closes the outside air inlet 11a and opens the indoor air inlet 11b, the operation mode is switched to an indoor air recirculation mode in which the air flows from the indoor air inlet 11b into the airflow passage 11.Moreover, when the inlet switching damper 13 is placed between the outside air inlet 11a and the indoor air inlet 11b, and the outside air inlet 11a and the indoor air inlet 11b open, the operation mode is switched to a two-way operation mode in which the air flows into the air flow passage 11 from both the outside air inlet 11a and the indoor air inlet 11b according to the opening ratio of the outside air inlet 11a and the indoor air inlet 11b.

[0103] The outlet switching dampers 13b, 13c, and 13d, which are configured to open and close the foot outlet 11c, the ventilation outlet 11d, and the defroster outlet 11e, are provided on the second side of the air flow passage 11, respectively, in the foot outlet 11c, the ventilation outlet 11d, and the defroster outlet 11e. These outlet switching dampers 13b, 13c, and 13d are configured to move together through a linkage (not shown) and are opened and closed by the electric motor 13e. Here, when the outlet switching dampers 13b, 13c, and 13d open the foot outlet 11c, close the ventilation outlet 11d, and slightly open the defroster outlet 11e, most of the air flowing through the air flow passage 11 flows out of the foot outlet 11c, and the remaining air is blown out of the defroster outlet 11e. This operation mode is referred to as "foot operation mode."Meanwhile, when the outlet switching dampers 13b, 13c, and 13d close the foot outlet 11c and the defroster outlet 11e and open the ventilation outlet 11d, all the air flowing through the air flow passage 11 is blown out of the ventilation outlet 11d. This operation mode is referred to as "ventilation mode." In addition, when the outlet switching dampers 13b, 13c, and 13d open the foot outlet 11c and the ventilation outlet 11d and close the defroster outlet 11e, the air flowing through the air flow passage 11 is blown out of the foot outlet 11c and the ventilation outlet 11d. This operation mode is referred to as "two-level mode." Furthermore, when the outlet switching dampers 13b, 13c, and 13d close the foot outlet 11c and the ventilation outlet 11d and open the defroster outlet 11e, the air flowing through the air flow passage 11 is blown out of the defroster outlet 11e. This operation mode is referred to as "defroster mode."Furthermore, when the outlet switching dampers 13b, 13c, and 13d close the ventilation outlet 11d and open the foot outlet 11c and the defroster outlet 11e, the air flowing through the air flow passage 11 is blown out of the foot outlet 11c and the defroster outlet 11e. This operation mode is referred to as the "defroster foot mode." Here, in the two-level operation mode, the air flow passage 11, the foot outlet 11c, the ventilation outlet 11d, and the heat exchanger and the radiator described later are arranged and configured so that the temperature of the air blown out of the foot outlet 11c is higher than the temperature of the air blown out of the ventilation outlet 11d.

[0104] The heat exchanger 14 is provided in the air flow passage 11 downstream of the air flow from the indoor fan 12. The heat exchanger 14 is configured to cool and dehumidify the air flowing through the air flow passage 11. In addition, the radiator 15 is provided in the air flow passage 11 downstream of the air flow from the heat exchanger 14. The radiator 15 is configured to heat the air flowing through the air flow passage 11. The heat exchanger 14 and the radiator 15 are heat exchangers, each formed by fins and tubes, and configured to perform heat exchange between the refrigerant flowing through the refrigerant circuit 20 and the air flowing through the air flow passage 11.

[0105] The air mixing damper 16 is provided between the heat exchanger 14 and the radiator 15 in the air flow passage 11 and is configured to control the percentage of air to be heated flowing through the air flow passage 11. The air mixing damper 16 is driven by the electric motor 16a. When the air mixing damper is arranged upstream of the radiator 15 in the air flow passage 11, the percentage of air subjected to heat exchange in the radiator 15 is reduced. Meanwhile, when the air mixing damper 16 is moved to a position different from the radiator 15 in the air flow passage 11, the percentage of air subjected to heat exchange is increased.In the air flow passage 11, when the air mixing damper 16 closes the upstream side of the radiator 15 and opens the portion other than the radiator 15, the opening is 0% and, on the other hand, when the air mixing damper 16 opens the upstream side of the radiator 15 and closes the portion other than the radiator 15, the opening is 100%.

[0106] The refrigerant circuit 20 includes: the heat exchanger 14, the radiator 15, the compressor 21 configured to compress a refrigerant; the outdoor heat exchanger 22 configured to perform heat exchange between the refrigerant and the outside air; the indoor heat exchanger 23 configured to perform heat exchange between the refrigerant flowing out of the radiator 15 or through the outdoor heat exchanger 22 and the refrigerant flowing out of the heat exchanger 14; the three-way valve 24 configured to switch the passage of the refrigerant; the first to fourth solenoid valves 25a to 25d; the first and second check valves 26a and 26b; the first and second expansion valves 27a and 27b configured to decompress the flowing refrigerant; the collection tank 28 configured to accumulate additional refrigerant;and the accumulator 29, which is configured to separate the refrigerant vapor from the refrigerant liquid to prevent the refrigerant liquid from being sucked into the compressor 21. These components are connected by a copper or aluminum pipe. The compressor 21 and the outdoor heat exchanger 22 are arranged outside the vehicle interior. The compressor 21 is driven by the electric motor 21a. The outdoor heat exchanger 22 is provided with the outdoor fan 30, which is configured to perform heat exchange between the outside air and the refrigerant when the vehicle is stopped. The outdoor fan 30 is driven by the electric motor 30a. The first expansion valve 27a is an electronic expansion valve with an adjustable opening.

[0107] To be more specific, the inlet side of the radiator 15, into which the refrigerant flows, is connected to the discharge side of the compressor 21, from which the refrigerant is discharged, to form the refrigerant flow passage 20a. In addition, the inlet side of the heat exchanger 22, into which the refrigerant flows, is connected to the outlet side of the radiator 15, from which the refrigerant is discharged, to thereby form the refrigerant flow passage 20b. The three-way valve 24 is provided in the refrigerant flow passage 20b. One side of the three-way valve 24, from which the refrigerant is discharged, and the other side, from which the refrigerant is discharged, are parallel to each other and are connected to the inlet side of the outdoor heat exchanger 22, into which the refrigerant flows, thereby forming the refrigerant flow passages 20c and 20d.In the refrigerant flow passage 20d, the header tank 28, the first expansion valve 27a, and the first check valve 26a are provided in order from the upstream of the refrigerant flow. The suction side of the compressor 21, into which the refrigerant is sucked, and the part of the refrigerant flow passage 20d between the three-way valve 24 and the header tank 28 are connected in parallel with the outlet side of the outdoor heat exchanger 22, from which the refrigerant is discharged, thereby forming the refrigerant flow passages 20e and 20f. The first solenoid valve 25a and the accumulator 29 are provided in the refrigerant flow passage 20e in order from the upstream of the refrigerant flow. The second solenoid valve 25b and the second check valve 26b are provided in the refrigerant flow passage 20f in the order from the upstream of the flow of the refrigerant.The inlet side of the indoor heat exchanger 23, into which a high-pressure refrigerant flows, is connected to the part of the refrigerant flow passage 20d between the header tank 28 and the first expansion valve 27a, thereby forming the refrigerant flow passage 20g. The third solenoid valve 25c is provided in the refrigerant flow passage 20g. The inlet side of the heat exchanger 14, into which the refrigerant flows, is connected to the outlet side of the indoor heat exchanger 23, from which the high-pressure refrigerant is discharged, thereby forming the refrigerant flow passage 20h. The second expansion valve 27b is provided in the refrigerant flow passage 20h. The inlet side of the indoor heat exchanger 23, into which a low-pressure refrigerant flows, is connected to the outlet side of the heat exchanger 14, from which the refrigerant is discharged, thereby forming the refrigerant flow passage 20i.The portion of the refrigerant flow passage 20e between the first solenoid valve 25a and the accumulator 29 is connected to the outlet side of the indoor heat exchanger 23, from which the low-pressure refrigerant is discharged, to thereby provide the refrigerant flow passage 20j. The inlet side of the outdoor heat exchanger 22, into which the refrigerant flows, is connected to the refrigerant flow passage 20a, to thereby form the refrigerant flow passage 20k. The fourth solenoid valve 25b is provided in the refrigerant flow passage 20k.

[0108] In addition, the vehicle air conditioning device also includes a control device 40 that controls the temperature and humidity of the vehicle interior to be the preset temperature and humidity.

[0109] The control device 40 includes a CPU, a ROM, and a RAM. In the control device, the CPU reads the program stored in the ROM according to the input signal via an input signal from a device connected to the input side, stores the state detected by the input signal in the RAM, and transmits an output signal to a device connected to the output side.

[0110] As in Fig. 19, the electric motor 12a for driving the indoor fan 12; the electric motor 13a for driving the inlet switching damper 13; the electric motor 13e for driving the outlet switching dampers 13b, 13c, and 13d; the electric motor 16a for driving the air mixing damper 16; the electric motor 21a for driving the compressor 21; the three-way valve 24; the first to fourth solenoid valves 25a to 25d; the first expansion valve 27a; and the electric motor 30a for driving the outdoor fan 30 are connected to the output side of the control device 40.

[0111] As in Fig. 19 are the outside air temperature sensor 41 configured to detect a temperature Tam outside the vehicle interior; the indoor air temperature sensor 42 configured to detect the indoor air temperature Tr; the inlet temperature sensor 43 configured to detect a temperature Ti of the air flowing into the air flow passage 11; the cooled air temperature sensor 44 configured to detect a temperature Te of the air cooled in the heat exchanger 14; the heated air temperature sensor 45 configured to detect a temperature Tc of the air heated in the radiator 15; the indoor air humidity sensor 46 configured to detect an indoor air humidity Th; the solar radiation sensor 48, such as a photosensor, configured to detect an amount of solar radiation Ts;the speed sensor 49, which is configured to detect a speed V of the vehicle; and the operating part 50, which is configured to set operating modes regarding the target setting temperature Tset and switching of the operation, are connected to the input side of the control device 40;

[0112] The vehicle air conditioning device having the above-described configuration performs a cooling operation, a cooling and dehumidifying operation, a heating operation, a first heating and dehumidifying operation, a second heating and dehumidifying operation, and a defrosting operation. Each operation will now be explained.

[0113] During the cooling operation and the cooling and dehumidifying operation, in the refrigerant circuit 20, the flow passage of the three-way valve 24 is set to the side of the refrigerant flow passage 20c; the second and third solenoid valves 25b and 25c are opened, and the first and fourth solenoid valves 25a and 25d are closed; and the compressor 21 is operated. By this measure, as shown in Fig. 20, the refrigerant discharged from the compressor 21 passes in this order through: the refrigerant flow passage 20a; the radiator 15; the refrigerant flow passages 20d and 20c; the outdoor heat exchanger 22; the refrigerant flow passages 20f, 20d, and 20g; the high-pressure side of the indoor heat exchanger 23; the refrigerant flow passage 20h; the heat exchanger 14; the refrigerant flow passage 20i; the low-pressure side of the indoor heat exchanger 23; and the refrigerant flow passages 20j and 20e, and is sucked into the compressor 21. The refrigerant flowing through the refrigerant circuit 20 releases the heat in the outdoor heat exchanger 22 and absorbs the heat in the heat exchanger 14. When the air mixing damper 16 is opened during the cooling and dehumidification operation, the refrigerant also releases the heat into the radiator 15.

[0114] In this case, in the air conditioning unit 10, during the cooling operation, the interior fan 12 is operated to flow the air through the air flow passage 11, and the air undergoes heat exchange with the refrigerant in the heat exchanger 14 and is cooled. The temperature of the cooled air becomes the target air blowing temperature TAO of the air to be blown out from the outlets 11c, 11d, and 11e to adjust the temperature of the vehicle interior to the target setting temperature Tset. Then, the air is blown into the vehicle interior at the temperature TAO. The target air blowing temperature TAO is calculated based on the preset temperature Tset and environmental conditions such as the outside air temperature Tam, the inside air temperature Tr, and a degree of solar radiation Ts, which are respectively detected by the outside air temperature sensor 41, the inside air temperature sensor 42, and the solar radiation sensor 48.

[0115] Meanwhile, in the air conditioning unit 10, during the cooling and dehumidification operation, the interior fan 12 is operated to flow the air through the air flow passage 11. The air undergoes heat exchange with the refrigerant that absorbs heat in the heat exchanger 14, and is thus cooled and dehumidified. The air dehumidified in the heat exchanger 14 undergoes heat exchange with the refrigerant that releases heat in the radiator 15, and is thus warmed. As a result, the air is blown into the vehicle interior at the target air blowing temperature TAO.

[0116] During the heating operation, in the refrigerant circuit 20, the flow passage of the three-way valve 24 is set to the side of the refrigerant flow passage 20d; the first solenoid valve 25a is opened and the second to fourth solenoid valves 25b to 25d are closed; and the compressor 21 is operated. By this measure, as shown in Fig. 21, the refrigerant discharged from the compressor 21 passes in this order through: 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 20e, and is sucked into the compressor 21. The refrigerant flowing through the refrigerant circuit 20 releases the heat in the radiator 15 and absorbs the heat in the outdoor heat exchanger 22.

[0117] In this case, in the air conditioning unit 10, the interior fan 12 is operated to force the air through the air flow passage 11, and the air does not undergo heat exchange with the refrigerant in the heat exchanger 14, but rather undergoes heat exchange with the refrigerant in the radiator 15 and is therefore warmed up. As a result, the air is blown into the vehicle interior at the target air blowing temperature TAO.

[0118] During the heating and dehumidifying operation, in the refrigerant circuit 20, the flow passage of the three-way valve 24 is set to the side of the refrigerant flow passage 20d; the first and third solenoid valves 25a and 25c are opened, and the second and fourth solenoid valves 25b and 25d are closed; and the compressor 21 is operated. By this measure, as shown in Fig. 22, the refrigerant discharged from the compressor 21 passes through, in this order: the refrigerant flow passage 20a; the radiator 15; and the refrigerant flow passages 20b and 20d. Part of the refrigerant flowing through the refrigerant flow passage 20d passes through, in this order: the outdoor heat exchanger 22; and the refrigerant flow passage 20e, and is sucked into the compressor 21. Meanwhile, the remaining refrigerant flowing through the refrigerant flow passage 20d passes through, in this order: the refrigerant flow passage 20g; the high-pressure side of the indoor heat exchanger 23; the refrigerant flow passage 20h; the heat exchanger 14; the refrigerant flow passage 20i; the low-pressure side of the indoor heat exchanger 23; and the refrigerant flow passages 20j and 20e, and is sucked into the compressor 21.The refrigerant flowing through the refrigerant circuit 20 releases the heat in the radiator 15 and absorbs the heat in the heat exchanger 14 and the outdoor heat exchanger 22.

[0119] In this case, in the air conditioning unit 10, the interior fan 12 is operated to force air through the airflow passage 11. The flowing air undergoes heat exchange with the refrigerant in the heat exchanger 14 and is thus cooled and dehumidified. Part of the air dehumidified in the heat exchanger 14 undergoes heat exchange with the refrigerant in the radiator 15 and is heated. As a result, the air is blown into the vehicle interior at the target air blowing temperature TAO.

[0120] During the second heating and dehumidifying operation, in the refrigerant circuit 20, the flow passage of the three-way valve 24 is set to the side of the refrigerant flow passage 20d; the third solenoid valve 25c is opened, and the first, second, and fourth solenoid valves 25a, 25b, and 25d are closed; and the compressor is operated. By this measure, as shown in Fig. 23, the refrigerant discharged from the compressor 21 passes in this order through: the refrigerant flow passage 20a; the radiator 15; the refrigerant flow passages 20b, 20d, and 20g; the high-pressure side of the indoor heat exchanger 23; the refrigerant flow passage 20h; the heat exchanger 14; the refrigerant flow passage 20i; the low-pressure side of the indoor heat exchanger 23; and the refrigerant flow passages 20j and 20e, and is sucked into the compressor 21. The refrigerant flowing through the refrigerant circuit 20 releases heat in the radiator 15 and absorbs heat in the heat exchanger 14.

[0121] In this case, in the air conditioning unit 10, the interior fan 12 is operated to force air through the air flow passage 11. The flowing air undergoes heat exchange with the refrigerant in the heat exchanger 14 and is thus cooled and dehumidified in the same way as in the first heating and dehumidification operation. Part of the air dehumidified in the heat exchanger 14 undergoes heat exchange with the refrigerant in the radiator 15 and is thus heated. As a result, the air is blown into the vehicle interior at the target air blowing temperature TAO.

[0122] During the defrosting operation, in the refrigerant circuit 20, the flow passage of the three-way valve 24 is set to the side of the refrigerant flow passage 20d; the first and fourth solenoid valves 25a and 25d are opened, and the second and third solenoid valves 25d and 25c are closed; and the compressor 21 is operated. By this measure, as shown in Fig. As shown in Figure 24, a portion of the refrigerant discharged from the compressor 21 passes through the refrigerant flow passage 20a, the radiator 15, and the refrigerant flow passages 20b and 20d, in this order, and flows into the outdoor heat exchanger 22. Meanwhile, the remaining 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 from 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 releases the heat in the radiator 15 and, at this time, absorbs the heat in the outdoor heat exchanger 22.

[0123] In this case, in the air conditioning unit 10, the interior fan 12 is operated to flow the air through the air flow passage 11. The flowing air does not undergo heat exchange with the refrigerant in the heat exchanger 14, but undergoes heat exchange with the refrigerant that releases heat in the radiator 15, and is therefore heated and then blown to the vehicle interior.

[0124] While the automatic switch is turned on, the control device 40 executes an operation switching control process to switch the operation between the cooling operation, the cooling and dehumidifying operation, the heating operation, the first heating and dehumidifying operation, the second heating and dehumidifying operation, and the defrosting operation based on environmental conditions including the outside air temperature Tam, the indoor air temperature Tr, the indoor air humidity Th, and the amount of solar radiation Ts.

[0125] The operation switching control process can be set to three operation modes according to the energy consumption of the air conditioning system. The three operation modes include a normal operation mode, a first energy-saving operation mode, and a second energy-saving operation mode, which are selected by the passenger operating the operating part 50. In the first energy-saving operation mode, when it is determined that the conditions for fogging the window glass are met, the first heating and dehumidifying operation or the second heating and dehumidifying operation is performed. In this first energy-saving operation mode, the energy consumption is lower than in the normal operation mode. In the second energy-saving operation mode, neither the first heating and dehumidifying operation nor the second heating and dehumidifying operation is performed.In this second energy saving mode, energy consumption is lower than in the normal mode and the first energy saving mode.

[0126] First, the operation switching control process in the normal mode is described with reference to the Fig. The flowchart shown in Figure 25 is described. (Step S41)

[0127] In step S41, the CPU determines whether the outside air temperature Tam is lower than the predetermined temperature T1 (e.g., 5 degrees Celsius). If it is determined that the outside air temperature Tam is lower than the predetermined temperature T1, the CPU proceeds to step S42. Otherwise, if it is determined that the outside air temperature Tam is the predetermined temperature T1 or higher, the CPU proceeds to step S43. (Step S42)

[0128] When it is determined in step S41 that the outside air temperature Tam is lower than the predetermined temperature T1, the CPU determines to perform the heating operation in step S42 and ends the operation switching control process. (Step S43)

[0129] If it is determined in step S41 that the outside air temperature Tam is the predetermined temperature T1 or higher, the CPU determines in step S43 whether the target air blowing temperature TAO is the predetermined temperature T2 (e.g., 25 degrees Celsius) or higher. If it is determined that the target air blowing temperature TAO is the predetermined temperature T2 or higher, the CPU proceeds to step S44. Otherwise, if it is determined that the target air blowing temperature TAO is lower than the predetermined temperature T2, the CPU proceeds to step S46. (Step S44)

[0130] If it is determined in step S43 that the target air blowing temperature TAO is the predetermined temperature T2 or higher, the CPU determines in step S44 whether the outside air temperature Tam is lower than the predetermined temperature T3 (e.g., 15 degrees Celsius, T2>T3). If it is determined that the outside air temperature Tam is lower than the predetermined temperature T3, the CPU proceeds to step S45. Otherwise, if it is determined that the outside air temperature Tam is the predetermined temperature T3 or higher, the CPU proceeds to step S48. (Step S45)

[0131] When it is determined in step S44 that the outside air temperature Tam is lower than the predetermined temperature T3, the CPU determines to perform the first heating and dehumidifying operation in step S45 and ends the operation switching control process. (Step S46)

[0132] If it is determined in step S43 that the target air blowing temperature TAO is lower than the predetermined temperature T2, the CPU determines in step S46 whether or not the target air blowing temperature TAO is higher than the outside air temperature Tam. If it is determined that the target air blowing temperature TAO is higher than the outside air temperature Tam, the CPU proceeds to step S47. Otherwise, if it is determined that the target air blowing temperature TAO is the outside air temperature Tam or lower, the CPU proceeds to step S49. (Step S47)

[0133] If it is determined in step S46 that the target air blowing temperature TAO is higher than the outside air temperature Tam, the CPU determines in step S47 whether the outside air temperature Tam is lower than the predetermined temperature T4 (e.g., 20 to 25 degrees Celsius). If it is determined that the outside air temperature Tam is lower than the predetermined temperature T4, the CPU proceeds to step S48. Otherwise, if it is determined that the outside air temperature Tam is the predetermined temperature T4 or higher, the CPU proceeds to step S49. (Step S48)

[0134] When it is determined in step S44 that the outside air temperature Tam is the predetermined temperature T3 or higher, or when it is determined in step S47 that the outside air temperature Tam is lower than the predetermined temperature T4, the CPU determines to perform the second heating and dehumidifying operation in step S48 and ends the operation switching control process. (Step S49)

[0135] When it is determined in step S46 that the target air blowing temperature TAO is the outside air temperature Tam or lower, or when it is determined in step S47 that the outside air temperature Tam is the predetermined temperature T4 or higher, the CPU determines to perform the cooling operation or the cooling and dehumidifying operation in step S49 and ends the operation switching control process.

[0136] Next, the operation switching control process in the first power saving mode is described with reference to the Fig. The flowchart shown in Figure 26 is described. (Step S51)

[0137] In step S51, the CPU determines whether the outside air temperature Tam is lower than the predetermined temperature T1 (e.g., 5 degrees Celsius). If it is determined that the outside air temperature Tam is lower than the predetermined temperature T1, the CPU proceeds to step S52. Otherwise, if it is determined that the outside air temperature Tam is the predetermined temperature T1 or higher, the CPU proceeds to step S53. (Step S52)

[0138] When it is determined in step S51 that the outside air temperature Tam is lower than the predetermined temperature T1, or when it is determined that the conditions for fogging the window glasses are not satisfied based on the determination in step S55 and step S59 described later, the CPU determines to perform the heating operation in step S52 and ends the operation switching control process. (Step S53)

[0139] If it is determined in step S51 that the outside air temperature Tam is the predetermined temperature T1 or higher, the CPU determines in step S53 whether or not the target air blowing temperature TAO is the predetermined temperature T2 (e.g., 25 degrees Celsius) or higher. If it is determined that the target air blowing temperature TAO is the predetermined temperature T2 or higher, the CPU proceeds to step S54. Otherwise, if it is determined that the target air blowing temperature TAO is lower than the predetermined temperature T2, the CPU proceeds to step S57. (Step S54)

[0140] If it is determined in step S53 that the target air blowing temperature TAO is the predetermined temperature T2 or higher, the CPU determines in step S54 whether or not the outside air temperature Tam is lower than the predetermined temperature T3 (e.g., 15 degrees Celsius, T2>T3). If it is determined that the outside air temperature Tam is lower than the predetermined temperature T3, the CPU proceeds to step S55. Otherwise, if it is determined that the outside air temperature Tam is the predetermined temperature T3 or higher, the CPU proceeds to step S59. (Step S55)

[0141] If it is determined in step S54 that the outside air temperature Tam is lower than the predetermined temperature T3, the CPU determines in step S55 whether the conditions for fogging the window glass are met. If it is determined that the conditions for fogging the window glass are met, the CPU proceeds to step S56. Otherwise, if it is determined that the conditions for fogging the window glass are not met, the CPU proceeds to step S52.Here, the determination of whether the conditions for fogging the window glasses are met is made based on an estimated temperature of the surface of the window glasses calculated based on the outside air temperature Tam, the interior air temperature Tr, the degree of solar radiation Ts, and the speed V of the vehicle, and also based on a condensation point temperature calculated based on the interior air temperature Tr and the interior air humidity Th. To be more specific, the CPU determines that the conditions for fogging the window glasses are met when the estimated temperature of the surface of the window glasses is the condensation point temperature or lower. Otherwise, the CPU determines that the conditions for fogging the window glasses are not met when the estimated temperature of the surface of the window glasses is higher than the condensation point temperature of the air in the vehicle interior. (Step S56)

[0142] When it is determined in step S55 that the conditions for fogging the window glasses are met, the CPU determines in step S56 to perform the first heating and dehumidifying operation and ends the operation switching control process. (Step S57)

[0143] If it is determined in step S53 that the target air blowing temperature TAO is lower than the predetermined temperature T2, the CPU determines in step S57 whether or not the target air blowing temperature TAO is higher than the outside air temperature Tam. If it is determined that the target air blowing temperature TAO is higher than the outside air temperature Tam, the CPU proceeds to step S58. Otherwise, if it is determined that the target air blowing temperature TAO is the outside air temperature Tam or lower, the CPU proceeds to step S61. (Step S58)

[0144] If it is determined in step S57 that the target air blowing temperature TAO is higher than the outside air temperature Tam, the CPU determines in step S58 whether the outside air temperature Tam is lower than the predetermined temperature T4 (e.g., 20 to 25 degrees Celsius). If it is determined that the outside air temperature Tam is lower than the predetermined temperature T4, the CPU proceeds to step S59. Otherwise, if it is determined that the outside air temperature Tam is the predetermined temperature T4 or higher, the CPU proceeds to step S61. (Step S59)

[0145] If it is determined in step S54 that the outside air temperature Tam is the predetermined temperature T3 or higher, or if it is determined in step S58 that the outside air temperature Tam is lower than the predetermined temperature T4, the CPU determines in step S59 whether the conditions for fogging the window glass are met. If it is determined that the conditions for fogging the window glass are met, the CPU proceeds to step S60. Otherwise, if it is determined that the conditions for fogging the window glass are not met, the CPU proceeds to step S52. (Step S60)

[0146] When it is determined in step S59 that the conditions for fogging the window glasses are met, the CPU determines to perform the second heating and dehumidifying operation in step S60 and ends the operation switching control process. (Step S61)

[0147] When it is determined in step S57 that the target air blowing temperature TAO is the outside air temperature Tam or lower, or when it is determined in step S58 that the outside air temperature Tam is the predetermined temperature T4 or higher, the CPU determines to perform the cooling operation or the cooling and dehumidifying operation in step S61 and ends the operation switching control process.

[0148] Next, the operation switching control process in the second power saving mode will be described with reference to the Fig. The flowchart shown in Figure 27 is described. (Step S71)

[0149] In step S71, the CPU determines whether the target air blowing temperature TAO is higher than the outside air temperature Tam. If it is determined that the target air blowing temperature TAO is higher than the outside air temperature Tam, the CPU proceeds to step S72. Otherwise, if it is determined that the target air blowing temperature TAO is the outside air temperature Tam or lower, the CPU proceeds to step S73. (Step S72)

[0150] When it is determined in step S71 that the target air blowing temperature TAO is higher than the outside air temperature Tam, the CPU determines to execute the heating operation in step S72 and ends the operation switching control process. (Step S73)

[0151] When it is determined in step S71 that the target air blowing temperature TAO is the outside air temperature Tam or lower, the CPU determines to perform the cooling operation or the cooling and dehumidifying operation in step S73 and ends the operation switching control process.

[0152] Next, a control method of the electric motor 21a and the electric motor 16a will be described. The electric motor 21a drives the compressor 21, and the electric motor 16a drives the air mixing damper 16 to allow air with the target air blowing temperature TAO to be blown out from the outlets 11c, 11d, and 11e.

[0153] First, the target air blowing temperature TAO is calculated based on the preset temperature Tset and environmental conditions such as the outside air temperature Tam, the indoor air temperature Tr, and an amount of solar radiation Ts, which are respectively detected by the outside air temperature sensor 41, the indoor air temperature sensor 42, and the solar radiation sensor 48.

[0154] In the normal mode and the second energy-saving mode, during the cooling operation and the cooling and dehumidifying operation, the rotational speed of the electric motor 21a is controlled based on the temperature detected by the cooled air temperature sensor 44 so that the temperature Te of the air cooled in the heat exchanger 14 is the predetermined target temperature Tet.

[0155] Meanwhile, in the first energy-saving mode, during the cooling operation and the cooling and dehumidification operation, the rotational speed of the electric motor 21a is controlled so that the temperature Te of the air cooled in the heat exchanger 14 is the target temperature Tet, that is, the condensation point temperature of the air at absolute humidity, in order to prevent the window glasses of the vehicle interior from fogging. Here, the target temperature Tet is calculated based on the outside air temperature Tam and the inside air temperature Tr, which are respectively detected by the outside air temperature sensor 41 and the inside air temperature sensor 42.

[0156] During the cooling operation and the cooling and dehumidifying operation, the temperature of the refrigerant flowing through the radiator 15 changes according to the outside air temperature Tam. Therefore, the estimated temperature Tct of the air heated in the radiator 15 is estimated based on the outside air temperature Tam.

[0157] During cooling operation and cooling and dehumidification operation, the outlet switching dampers 13b, 13c, and 13d are switched to the ventilation mode. The air mixing damper 16 is controlled to open to an opening SW calculated from the target air blowing temperature Ta, the estimated temperature Tct, and the target temperature Tet (SW=(TAO-Tet / (Tct-Tet)).

[0158] Since the refrigerant does not flow into the heat exchanger 14 during the heating operation, the target temperature Tet for the air cooled in the heat exchanger 14 is not set. During the heating operation, when the outlet switching dampers 13b, 13c, and 13d are set to the foot mode, the rotational speed of the electric motor 21a is controlled so that the temperature Tc of the air heated in the radiator 15 is the target heating temperature Tct, which is obtained based on the temperature detected by the heated air temperature sensor 45 by adding the predetermined temperature α to the target air blowing temperature TAO. Here, the predetermined temperature α is equivalent to the amount of heat while the refrigerant flows through the air flow passage 11. In this case, the opening of the air mixing damper 16 is set to 100%.

[0159] In addition, during the heating operation, when the outlet switching dampers 13b, 13c, and 13d are set to the two-level mode, the rotational speed of the electric motor 21a is controlled so that the temperature Tc of the air heated in the radiator 15 is the target heated temperature Tct, which is determined based on the temperature detected by the heated air temperature sensor 45 by adding the predetermined value β(α<β) to the target air blowing temperature TAO. Here, in the two-level mode, there is a predetermined temperature difference between the air blown from the foot outlet 11c and the air blown from the ventilation outlet 11d, so that part of the air flowing through the air flow passage 11 is not subjected to heat exchange.Therefore, the predetermined value β is the temperature corresponding to the amount of heat required to adjust the average temperature of all the air flowing through the air flow passage 11 to the target air blowing temperature TAO.

[0160] As described above, the opening SW of the air mixing damper 16 is calculated based on the target air blowing temperature TAO, the temperature Te of the air cooled in the heat exchanger 14, and the temperature Tc of the air heated in the radiator 15 (SW=(TAO-Te) / (Tc-Te)). During the heating operation, since the refrigerant does not flow into the heat exchanger 14, the temperature Te is one of the outside air temperature Tam and the indoor air temperature Tr, or the mixed air temperature of the outside air and the indoor air. When the opening SW is a fixed value (0.5 to 0.7), the temperature Tc is calculated based on the opening SW of the air mixing damper 16, the target air blowing temperature TAO, and the temperature Tc (Tc=(TAO-Te) / SW+Te). Therefore, when the outlet switching dampers 13b, 13c and 13d are set to the two-level operation mode, the target heated temperature Tct for the radiator 15 is calculated from the following equation. Tct=TAO+β=(TAO−Te) / SW+Te

[0161] In this case, the opening SW of the air mixing slide 16 is controlled within the range of, for example, 50% to 70%.

[0162] In the normal mode, during the first heating and dehumidifying operation, the opening of the first expansion valve 27a is controlled so that the temperature Te of the air cooled in the heat exchanger 14 is the predetermined target temperature Tet based on the temperature detected by the cooled air temperature sensor 44. Meanwhile, in the first energy-saving mode, the opening of the first expansion valve 27a is controlled so that the temperature Te of the air cooled in the heat exchanger 14 is the target temperature Tet, that is, the condensation temperature of the air at absolute humidity, in order to prevent the window glasses of the vehicle interior from fogging.

[0163] In addition, during the first heating and dehumidification operation, when the outlet switching dampers 13b, 13c, and 13d are set to the foot mode, the ventilation mode, the defroster mode, or the defroster foot mode, the rotational speed of the electric motor 21a is controlled so that the temperature Tc of the air heated in the radiator 15 is the target heated temperature Tct obtained based on the temperature detected by the heated air temperature sensor 45 by adding the predetermined value α to the target air blowing temperature TAO in the same manner as in the foot mode during the heating operation. In this case, the opening SW of the air mixing damper is set to 100%.

[0164] Moreover, during the first heating and dehumidifying operation, the rotational speed of the electric motor 21a is controlled so that the temperature Tc of the air heated in the radiator 15 is the target heated temperature Tct obtained based on the temperature detected by the heated air temperature sensor 45 by adding the predetermined value β (α<β) to the target air blowing temperature TAO in the same manner in the two-level mode during the heating operation.

[0165] In this case, the opening SW of the air mixing damper 16 is controlled within the range of, for example, 50% to 70% in the same manner as in the two-level mode during the heating operation.

[0166] During the second heating and dehumidifying operation, the rotational speed of the electric motor 21a is controlled so that the temperature Te of the air cooled in the heat exchanger 14 is the predetermined target temperature Tet.

[0167] In addition, during the second heating and dehumidifying operation, the opening SW of the air mixing damper 16 is controlled so that the temperature of the air blown from each of the outlets 11c, 11d and 11e is the target air blowing temperature TAO.

[0168] The control device 40 switches the operation mode between the foot operation mode, the ventilation mode, and the two-level operation mode depending on the target air blowing temperature TAO during each operation switched by the operation switching control process. To be more specific, the control device 40 sets the foot operation mode when the target air blowing temperature TAO is high, e.g., 40 degrees Celsius. Meanwhile, the control device 40 sets the ventilation mode when the target air blowing temperature TAO is low, e.g., lower than 25 degrees Celsius. Moreover, the control device 40 sets the two-level operation mode when the target air blowing temperature TAO is the temperature between the temperature for the foot operation mode and the temperature for the ventilation mode.

[0169] As described above, the vehicle air conditioning device according to the present invention has the normal operation mode for switching the operation to the heating operation, the heating and dehumidifying operation, the cooling operation, and the cooling and dehumidifying operation based on the ambient conditions; the first energy-saving operation mode for switching the operation to the heating operation, the heating and dehumidifying operation, the cooling operation, and the cooling and dehumidifying operation based on the ambient conditions, and, only when the fogging determination part determines that the conditions for fogging the window glasses are met, performs the heating and dehumidifying operation; and the second energy-saving operation mode for switching the operation to the heating operation, the cooling operation, and the cooling and dehumidifying operation based on the ambient conditions.These normal mode, first energy-saving mode, and second energy-saving mode can be switched by the operating part 50. This allows a passenger of the vehicle to switch the mode between the normal mode, the first energy-saving mode, and the second energy-saving mode. If the passenger selects the first energy-saving mode or the second energy-saving mode, whose power consumption is lower than the normal mode, it is possible to prevent the vehicle's cruising range from decreasing while continuously performing the air-conditioning operation in the vehicle interior.

[0170] In the normal operation mode, the heating operation is performed when the outside air temperature Tam is lower than the predetermined temperature T1; the first heating and dehumidifying operation is performed when the outside air temperature Tam is the predetermined temperature T1 or higher and the target air blowing temperature TAO is the predetermined temperature T2 or higher; the second heating and dehumidifying operation is performed when the outside air temperature is the predetermined temperature T1 or higher, the target air blowing temperature TAO is the predetermined temperature T2 or higher, and the outside air temperature is the predetermined temperature T3 or higher; the second heating and dehumidifying operation is performed when the outside air temperature is the predetermined temperature T1 or higher, the target air blowing temperature TAO is lower than the predetermined temperature T2 and higher than the outside air temperature Tam, and the outside air temperature Tam is lower than the predetermined temperature T4;the cooling operation or the cooling and dehumidifying operation is performed when the outside air temperature Tam is the predetermined temperature T1 or higher, the target air blowing temperature TAO is lower than the predetermined temperature T2 and higher than the outside air temperature Tam, and the outside air temperature is the predetermined temperature T4 or higher;and the cooling operation or the cooling and dehumidifying operation is performed when the outside temperature Tam is the predetermined temperature T1 or higher, the target air blowing temperature TAO is lower than the predetermined temperature T2, and the outside air temperature Tam is lower. By this measure, it is possible to reliably switch the operation between the heating operation, the first heating and dehumidifying operation, the second heating and dehumidifying operation, the cooling operation, and the cooling and dehumidifying operation. Consequently, it is possible to maintain the optimized temperature and humidity of the vehicle interior for the passengers.

[0171] In the first energy-saving mode, the heating operation is performed when the outside air temperature Tam is lower than the predetermined temperature T1; the heating operation is performed when the outside air temperature Tam is the predetermined temperature T1 or higher, the target air blowing temperature TAO is the predetermined temperature T2 or higher, the outside air temperature is lower than the predetermined temperature T3, and it is determined that the conditions for fogging the window glasses are not met; the first heating and dehumidifying operation is performed when the outside air temperature Tam is the predetermined temperature T1 or higher, the target air blowing temperature TAO is the predetermined temperature T2 or higher, the outside air temperature is lower than the predetermined temperature T3, and it is determined that the conditions for fogging the window glasses are met;The heating operation is performed when the outside air temperature Tam is the predetermined temperature T1 or higher, the target air blowing temperature TAO is the predetermined temperature T2 or higher, the outside air temperature is the predetermined temperature T3 or higher, and it is determined that the conditions for fogging the window glasses are not met; The second heating and dehumidifying operation is performed when the outside air temperature Tam is the predetermined temperature T1 or higher, the target air blowing temperature TAO is the predetermined temperature T2 or higher, the outside air temperature is the predetermined temperature T3 or higher, and it is determined that the conditions for fogging the window glasses are met;The heating operation is performed when the outside air temperature Tam is the predetermined temperature T1 or higher, the target air blowing temperature TAO is lower than the predetermined temperature T2 and higher than the outside air temperature Tam, the outside air temperature is lower than the predetermined temperature T4, and it is determined that the conditions for fogging the window glasses are not met; The second heating and dehumidifying operation is performed when the outside air temperature Tam is the predetermined temperature T1 or higher, the target air blowing temperature TAO is lower than the predetermined temperature T2 and higher than the outside air temperature Tam, the outside air temperature is lower than the predetermined temperature T4, and it is determined that the conditions for fogging the window glasses are met;The cooling operation or the cooling and dehumidifying operation is performed when the outside air temperature Tam is the predetermined temperature T1 or higher, the target air blowing temperature TAO is lower than the predetermined temperature T2 and higher than the outside air temperature Tam, and the outside air temperature Tam is higher than the predetermined temperature T4; The cooling operation or the cooling and dehumidifying operation is performed when the outside air temperature Tam is the predetermined temperature T1 or higher, and the target air blowing temperature TAO is lower than the predetermined temperature T2 and higher than the outside air temperature Tam;By this measure, in normal operation mode, when the conditions for switching to the first heating and dehumidification operation or the second heating and dehumidification operation are met, the first heating and dehumidification operation and the second heating and dehumidification operation are not performed. Instead, the heating operation is performed if it is determined that the conditions for fogging the window glass are not met. This measure makes it possible to reduce energy consumption compared to normal operation mode.

[0172] In the second energy-saving mode, when the target air blowing temperature TAO is higher than the outside air temperature Tam while the cooling operation or the cooling and dehumidification operation is being performed, the heating operation is performed when the target air blowing temperature TAO is the outside air temperature Tam or lower. By this measure, in the normal mode or the first energy-saving mode, when the conditions for switching the operation to the first heating and dehumidification operation or the second heating and dehumidification operation are met, the first heating and dehumidification operation or the second heating and dehumidification operation is not performed. Therefore, it is possible to reduce energy consumption compared to the normal mode and the first energy-saving mode.

[0173] In the foot-level mode, during the heating operation, the rotational speed of the electric motor 21a is controlled so that the temperature Tc of the air after heat exchange in the radiator 15 is the target heating temperature Tct, and the opening of the air mixing damper 16 is controlled to maximize the percentage of air in the radiator that undergoes heat exchange with the refrigerant. In the two-level mode, during the heating operation, the rotational speed of the electric motor 21a is controlled so that the temperature Tc of the air after heat exchange in the radiator 15 is the target heating temperature Tct, and the air mixing damper 16 is controlled to open to an opening within the range of 50% to 70%, which is calculated based on the target heating temperature Tct, the temperature Te of the air flowing into the air flow passage, and the target air blowing temperature TAO.By this measure, the rotational speed of the electric motor 21a and the opening of the air mixing damper 16 are controlled according to the operation mode of the outlet switching dampers 13b, 13c, and 13d. Therefore, it is possible to reliably adjust the temperature of the air blown to the vehicle interior to the target air blowing temperature TAO.

[0174] In addition, the target heating temperature Tct of the foot mode during the heating operation is obtained by adding the heat amount corresponding to the heat loss while the air flows through the air flow passage 11 from the air blown to the vehicle interior to the target air blowing temperature. The target heating temperature Tct of the two-level mode during the heating operation is calculated based on the target air blowing temperature TAO, the temperature of the air flowing into the air flow passage 11, and the opening of the air mixing damper 16. By this measure, the target heating temperature Tct is set based on the operation mode of the outlet switching dampers 13b, 13c, and 13d, and therefore, it is possible to adjust the temperature of the air blown to the vehicle interior to the target air blowing temperature TAO.

[0175] During the first heating and dehumidification operation, the opening of the first expansion valve 27a, which is provided on the inlet side of the outdoor heat exchanger 22 into which the refrigerant flows, is controlled so that the temperature Te of the air after heat exchange in the heat exchanger 14 is the target temperature Tet after the air is cooled and dehumidified. In the foot mode, the ventilation mode, the defroster mode, and the defroster-foot mode, during the first heating and dehumidification operation, the speed of the electric motor 21a is controlled so that the temperature Tc of the air after the air is dehumidified after heat exchange in the radiator 15 is the target heating temperature Tct, and the opening of the air mixing damper 16 is controlled to maximize the percentage of air undergoing heat exchange with the refrigerant in the radiator 15.In the two-level operation mode, during the first heating and dehumidifying operation, the rotational speed of the electric motor 21a is controlled so that the temperature Tc of the air after the dehumidification is the target heating temperature Tct after heat exchange in the radiator 15, and the air mixing damper 16 is controlled to open to the opening within the range of 50 to 70%, which is calculated based on the target air blowing temperature TAO, the target temperature Tet of the air that has been cooled and dehumidified, and the target heating temperature Tct of the air that has been dehumidified. By this measure, the rotational speed of the electric motor 21a and the opening of the air mixing damper 16 are controlled according to the operation mode of the outlet switching dampers 13b, 13c, and 13d. Therefore, it is possible to securely adjust the temperature of the air blown to the vehicle interior to the target air blowing temperature TAO.

[0176] During the first heating and dehumidifying operation, the target temperature Tet of the air that has been cooled and dehumidified is calculated based on the indoor air temperature Tr, the indoor air humidity Th, and the target air blowing temperature TAO to set the target temperature Tet of the air that has been cooled and dehumidified to a predetermined target temperature of the air that has been cooled and dehumidified in the first switching mode, and to set the indoor air humidity Th in the second switching mode to a predetermined humidity or lower.In the foot mode, the ventilation mode, the defroster mode, and the defroster-foot mode, during the first heating and dehumidification operation, the target heating temperature Tct of the air that has been dehumidified is obtained by adding the amount of heat corresponding to the heat loss from the air to be blown out to the vehicle interior while the air flows through the air flow passage 11 to the target air blowing temperature TAO. In the two-level mode, during the heating and dehumidification operation, the target heating temperature Tct of the air that has been dehumidified is calculated based on the target air blowing temperature TAO, the target temperature Tet of the air that has been cooled and dehumidified, and the opening of the air mix damper 16.By this measure, the target temperature Tet of the air that has been cooled and dehumidified and the target heating temperature Tct of the air that has been dehumidified are set based on the operation mode of the outlet switching dampers 13b, 13c, and 13d. Therefore, it is possible to adjust the temperature of the air blown to the vehicle interior to the target air blowing temperature TAO.

[0177] Furthermore, during the cooling operation and the cooling and dehumidifying operation, the rotational speed of the electric motor 21a is controlled so that the temperature Te of the air after heat exchange in the heat exchanger 14 is the target temperature Tet of the air that has been cooled; the temperature Tc of the air after heat exchange in the radiator 15 is estimated as the estimated temperature Tct; and the air mixing damper 16 is controlled to open to the opening calculated based on the target air blowing temperature TAO, the target temperature Tet of the air that has been cooled, and the estimated temperature Tct. By this measure, the rotational speed of the electric motor 21a and the opening of the air mixing damper 16 are controlled according to the operation mode of the outlet switching dampers 13b, 13c, and 13d. Therefore, it is possible to securely adjust the temperature of the air blown to the vehicle interior to the target air blowing temperature TAO.

[0178] The target temperature Tet of the air that has been cooled is calculated based on the interior air temperature Tr, the interior air humidity Th, and the target air blowing temperature TAO, so as to set the target temperature Tet of the air that has been cooled to a predetermined target temperature Tet of the air cooled in the first switching mode and the third switching mode, and to set the interior air humidity Th to a predetermined humidity or lower. By this measure, the target temperature Tet and the estimated temperature Tct after the air is cooled are set according to the operation mode of the outlet switching dampers 13b, 13c, and 13d. Therefore, it is possible to securely set the temperature of the air blown to the vehicle interior to the target air blowing temperature TAO.

[0179] Here, in the present embodiment, a configuration has been described in which the heat of the air flowing through the airflow passage 11, which undergoes heat exchange with the refrigerant in the radiator 15, is used as the heat source for the first and second heating and dehumidification operations and the cooling and dehumidification operations. However, this is by no means limiting. If the amount of heat is insufficient, an auxiliary heat source may be provided. For example, in addition to the radiator 15 in the airflow passage 11, an electric heater may be provided as a heat source, which can directly heat the airflow passage 11. In addition, a water heating circuit is formed across the inside and outside of the airflow passage 11 to heat the water flowing through the water heating circuit outside the airflow passage 11 and release the heat from the heated water into the airflow passage 11.

[0180] Additionally, the present embodiment described a configuration in which the three-way valve 24 is used to switch between the refrigerant flow passages 20c and 20d. However, this is by no means limiting. Instead of the three-way valve 24, two solenoid valves may be used to switch between the refrigerant flow passages 20c and 20d.

[0181] Furthermore, with the present embodiment, the operation switching control process is executed based on the outside air temperature Tam, the target air blowing temperature TAO calculated based on the ambient conditions, and the determination of whether the window glass fogging conditions are met. As the ambient conditions, at least one of the outside air temperature Tam, the indoor air temperature Tr, the indoor air humidity Th, and the degree of solar radiation is used.

[0182] Furthermore, with the present embodiment, in the second switching mode during the first cooling and dehumidifying operation, the target temperature Tet of the air that has been cooled and dehumidified is calculated based on the indoor air temperature Tr, the indoor air humidity Th, and the target air blowing temperature TAO. In the second switching mode, during the first heating and dehumidifying operation, the target temperature Tet of the air that has been cooled and dehumidified can be calculated based on at least one of the outside air temperature Tam, the indoor air temperature Tr, the indoor air humidity Th, the degree of solar radiation Ts, the vehicle speed V, and the target air blowing temperature TAO.

[0183] Furthermore, with the present embodiment, in the second switching mode, during the cooling operation and the cooling and dehumidifying operation, the target temperature Tet of the air that has been cooled is calculated based on the indoor air temperature Tr, the indoor air humidity Th, and the target air blowing temperature TAO. In the second switching mode, during the cooling operation and the cooling and dehumidifying operation, the target temperature Tet of the air that has been cooled can be calculated based on at least one of the outside air temperature Tam, the indoor air temperature Tr, the indoor air humidity Th, the degree of solar radiation Ts, the vehicle speed V, and the target air blowing temperature TAO.

[0184] Fig. 28 to 32 show Embodiment 6 according to the present invention.

[0185] As in Fig. 28, the vehicle air conditioning device according to the present invention includes the air conditioning unit 10 provided in the vehicle interior and the refrigerant circuit 20 formed across the vehicle interior and the exterior.

[0186] The air conditioning unit 10 includes an airflow passage 11 that allows air to be supplied to the vehicle interior to pass through. An outside air inlet 11a and an inside air inlet 11b are provided on the first end side of the airflow passage 11. The outside air inlet 11a is configured to allow outside air to flow into the airflow passage 11, and the inside air inlet 11b is configured to allow inside air to flow into the airflow passage 11. Meanwhile, a foot outlet 11c, a ventilation outlet 11d, and a defroster outlet 11e are provided on the second end side of the airflow passage 11. The foot outlet 11c is configured to allow the air flowing through the airflow passage 11 to be blown to the feet of the passengers in the vehicle.The ventilation outlet 11d is configured to allow the air flowing through the airflow passage 11 to be blown toward the upper bodies of the passengers in the vehicle. The defroster outlet 11e is configured to allow the air flowing through the airflow passage 11 to be blown toward the inner surface of the front window.

[0187] An interior fan 12, such as a sirocco fan, configured to allow air to flow through the airflow passage 11 from end to end, is provided on the first end side of the airflow passage 11. This interior fan 12 is driven by the electric motor 12a.

[0188] Also, on the first end side of the airflow passage 11, there is an inlet switching damper 13 configured to open one of the outside air inlet 11a and the indoor air inlet 11b and close the other. This inlet switching damper 13 is driven by the electric motor 13a. When the inlet switching damper 13 closes the indoor air inlet 11b and opens the outside air inlet 11a, the operation mode is switched to an outside air supply mode in which air flows from the outside air inlet 11a into the airflow passage 11. Meanwhile, when the inlet switching damper 13 closes the outside air inlet 11a and opens the indoor air inlet 11b, the operation mode is switched to an indoor air recirculation mode in which air flows from the indoor air inlet 11b into the airflow passage 11.Moreover, when the inlet switching damper 13 is placed between the outside air inlet 11a and the indoor air inlet 11b, and the outside air inlet 11a and the indoor air inlet 11b are opened, the operation mode is switched to a two-way operation mode in which the air flows into the air flow passage 11 from both the outside air inlet 11a and the indoor air inlet 11b according to the opening ratio of the outside air inlet 11a and the indoor air inlet 11b.

[0189] The outlet switching dampers 13b, 13c, and 13d, which are configured to open and close the foot outlet 11c, the ventilation outlet 11d, and the defroster outlet 11e, are provided in the foot outlet 11c, the ventilation outlet 11d, and the defroster outlet 11e, respectively, on the second side of the air flow passage 11. These outlet switching dampers 13b, 13c, and 13d are configured to move together by a rod (not shown) and are opened and closed by the electric motor 13e. Here, when the outlet switching dampers 13b, 13c, and 13d open the foot outlet 11c, close the ventilation outlet 11d, and slightly open the defroster outlet 11e, most of the air flowing through the air flow passage 11 is discharged from the foot outlet 11c, and the remaining air is discharged from the defroster outlet 11e. This operation mode is referred to as the "foot operation mode."Meanwhile, when the outlet switching dampers 13b, 13c, and 13d close the foot outlet 11c and the defroster outlet 11e and open the ventilation outlet 11d, all the air flowing through the air flow passage 11 is blown out of the ventilation outlet 11d. This operation mode is referred to as "ventilation mode." In addition, when the outlet switching dampers 13b, 13c, and 13d open the foot outlet 11c and the ventilation outlet 11d and close the defroster outlet 11e, the air flowing through the air flow passage 11 is blown out of the foot outlet 11c and the ventilation outlet 11d. This operation mode is referred to as "two-level mode." Furthermore, when the outlet switching dampers 13b, 13c, and 13d close the foot outlet 11c and the ventilation outlet 11d and open the defroster outlet 11e, the air flowing through the air flow passage 11 is blown out of the defroster outlet 11e. This operation mode is referred to as "defroster mode."Furthermore, when the outlet switching dampers 13b, 13c, and 13d close the ventilation outlet 11d and open the foot outlet 11c and the defroster outlet 11e, the air flowing through the air flow passage 11 is blown out of the foot outlet 11c and the defroster outlet 11e. This operation mode is referred to as "defroster foot mode." Here, in the two-level operation mode, the air flow passage 11, the foot outlet 11c, the ventilation outlet 11d, and a heat exchanger and a radiator, which will be described later, are arranged and configured so that the temperature of the air blown out of the foot outlet 11c is higher than the temperature of the air blown out of the ventilation outlet 11d.

[0190] The heat exchanger 14 is provided in the air flow passage 11 downstream of the air flow from the indoor fan 12. The heat exchanger 14 is configured to cool and dehumidify the air flowing through the air flow passage 11. In addition, the radiator 15 is provided in the air flow passage 11 downstream of the air flow from the heat exchanger 14. The radiator 15 is configured to heat the air flowing through the air flow passage 11. The heat exchanger 14 and the radiator 15 are heat exchangers, each formed by fins and tubes, and configured to perform heat exchange between the refrigerant flowing through the refrigerant circuit 20 and the air flowing through the air flow passage 11.

[0191] The air mixing damper 16 is provided in the air flow passage 11 between the heat exchanger 14 and the radiator 15 and is configured to control the percentage of air to be heated flowing through the air flow passage 11. The air mixing damper 16 is driven by the electric motor 16a. When the air mixing damper 16 is arranged upstream of the radiator 15 in the air flow passage 11, the percentage of air subjected to heat exchange in the radiator 15 is reduced. Meanwhile, when the air mixing damper 16 is moved to a position other than the radiator 15 in the air flow passage 11, the percentage of air subjected to heat exchange is increased.In the air flow passage 11, when the air mix damper 16 closes the upstream side of the radiator 15 and opens the portion other than the radiator 15, the opening is 0%, and otherwise, when the air mix damper 16 opens the upstream side of the radiator 15 and closes the portion other than the radiator 15, the opening is 100%.

[0192] The refrigerant circuit 20 includes: a heat exchanger 14; the radiator 15; the compressor 21 configured to compress a refrigerant; the outdoor heat exchanger 22 configured to perform heat exchange between the refrigerant and the outside air; the indoor heat exchanger 23 configured to perform heat exchange between the refrigerant flowing out of the radiator 15 or through the outdoor heat exchanger 22 and the refrigerant flowing out of the heat exchanger 14; the three-way valve 24 configured to switch the passage of the refrigerant; the first to fourth solenoid valves 25a to 25d; the first and second check valves 26a and 26b; the first and second expansion valves 27a and 27b configured to decompress the flowing refrigerant; the collection tank 28 configured to accumulate additional refrigerant.and the accumulator 29, which is configured to separate the refrigerant vapor from the refrigerant liquid to prevent the refrigerant liquid from being sucked into the compressor 21. These components are connected by a copper pipe or an aluminum pipe. The compressor 21 and the outdoor heat exchanger 22 are arranged outside the vehicle interior. The compressor 21 is driven by the electric motor 21a. The outdoor heat exchanger 22 is provided with the outdoor fan 30, which is configured to perform heat exchange between the outside air and the refrigerant when the vehicle is stopped. The outdoor fan 30 is driven by the electric motor 30a. The first expansion valve 27a is an electronic expansion valve with an adjustable opening.

[0193] To be more specific, the inlet side of the radiator 15, into which the refrigerant flows, is connected to the discharge side of the compressor 21, from which the refrigerant is discharged, to form the refrigerant flow passage 20a. In addition, the inlet side of the outdoor heat exchanger 22, into which the refrigerant flows, is connected to the outlet side of the radiator 15, from which the refrigerant is discharged, to thereby form the refrigerant flow passage 20b. The three-way valve 24 is provided in the refrigerant flow passage 20b. One side of the three-way valve 24, from which the refrigerant is discharged, and the other side, from which the refrigerant is discharged, are parallel to each other and are connected to the inlet side of the outdoor heat exchanger 22, into which the refrigerant flows, to thereby form the refrigerant flow passages 20c and 20d.In the refrigerant flow passage 20d, the header tank 28, the first expansion valve 27a, and the first check valve 26a are provided in order from the upstream of the refrigerant flow. The suction side of the compressor 21, into which the refrigerant is sucked, and the part of the refrigerant flow passage 20d between the three-way valve 24 and the header tank 28 are connected in parallel with the outlet side of the outdoor heat exchanger 22, from which the refrigerant is discharged, thereby forming the refrigerant flow passages 20e and 20f. The first solenoid valve 25a and the accumulator 29 are provided in the refrigerant flow passage 20e in order from the upstream of the refrigerant flow. The second solenoid valve 25b and the second check valve 26b are provided in the refrigerant flow passage 20f in the order from the upstream of the flow of the refrigerant.The inlet side of the indoor heat exchanger 23, into which a high-pressure refrigerant flows, is connected to the part of the refrigerant flow passage 20d between the header tank 28 and the first expansion valve 27a, thereby forming the refrigerant flow passage 20g. The third solenoid valve 25c is provided in the refrigerant flow passage 20g. The inlet side of the heat exchanger 14, into which the refrigerant flows, is connected to the outlet side of the indoor heat exchanger 23, from which the high-pressure refrigerant is discharged, thereby forming the refrigerant flow passage 20h. The second expansion valve 27b is provided in the refrigerant flow passage 20h. The inlet side of the indoor heat exchanger 23, into which a low-pressure refrigerant flows, is connected to the outlet side of the heat exchanger 14, from which the refrigerant is discharged, thereby forming the refrigerant flow passage 20i.The portion of the refrigerant flow passage 20e between the first solenoid valve 25a and the accumulator 29 is connected to the outlet side of the indoor heat exchanger 23, from which the low-pressure refrigerant is discharged, to thereby form the refrigerant flow passage 20j. The inlet side of the outdoor heat exchanger 22, into which the refrigerant flows, is connected to the refrigerant flow passage 20a, to thereby form the refrigerant flow passage 20k. The fourth solenoid valve 25d is provided in the refrigerant flow passage 20k.

[0194] In addition, the vehicle air conditioning device also includes a control device 40 that controls the temperature and humidity of the vehicle interior to be the preset temperature and humidity.

[0195] The control device 40 includes a CPU, a ROM, and a RAM. In the control device, the CPU, upon receiving an input signal from a device connected to the input side, reads the program stored in the ROM according to the input signal, stores the state detected by the input signal in the RAM, and transmits an output signal to the device connected to the output side.

[0196] As in Fig. 29, the electric motor 12a for driving the indoor fan 12; the electric motor 13a for driving the inlet switching damper 13; the electric motor 13e for driving the outlet switching dampers 13b, 13c, and 13d; the electric motor 16a for driving the air mixing damper 16; the electric motor 21a for driving the compressor 21; the three-way valve 24; the first to fourth solenoid valves 25a to 25b; the first expansion valve 27a; and the electric motor 30a for driving the outdoor fan 30 are connected to the output side of the control device 40.

[0197] As in Fig. 29 are the outside air temperature sensor 41 configured to detect a temperature Tam outside the vehicle interior; the inside air temperature sensor 42 configured to detect the temperature Tr in the vehicle interior; the inlet temperature sensor 43 configured to detect a temperature Ti of the air flowing into the air flow passage 11; the cooled air temperature sensor 44 configured to detect a temperature Te of the air cooled in the heat exchanger 14; the heated air temperature sensor 45 configured to detect a temperature Tc of the air heated in the radiator 15; the inside air humidity sensor 46 configured to detect the air humidity Th in the vehicle interior; a refrigerant temperature sensor 47 configured to detect a temperature Thex of the refrigerant after heat exchange in the outside heat exchanger 22;the solar radiation sensor 48, such as a photosensor, configured to detect an amount of solar radiation Ts; the speed sensor 49, configured to detect a speed V of the vehicle; the operating part 50, configured to set operation modes regarding the target setting temperature Tset and switching of the operation; and a pressure sensor 51, configured to detect a pressure P of the refrigerant in the outdoor heat exchanger 22, connected to the input side of the control device 40.

[0198] The vehicle air conditioning system, which has the configuration described above, performs a cooling operation, a cooling and dehumidifying operation, a heating operation, a heating and dehumidifying operation, and a defrosting operation. Each operation will now be explained.

[0199] During the cooling operation and the cooling and dehumidifying operation, in the refrigerant circuit 20, the flow passage of the three-way valve 24 is set to the side of the refrigerant flow passage 20c; the second and third solenoid valves 25b and 25c are opened, and the first and fourth solenoid valves 25a and 25d are closed; and the compressor 21 is operated. By this measure, as shown in Fig. 30, the refrigerant discharged from the compressor 21 passes in this order through: the refrigerant flow passage 20a; the radiator 15; the refrigerant flow passages 20b and 20c; the outdoor heat exchanger 22; the refrigerant flow passages 20f, 20d and 20g; the high pressure side of the indoor heat exchanger 23; the refrigerant flow passage 20h; the heat exchanger 14; the refrigerant flow passage 20i; the low pressure side of the indoor heat exchanger 23; and the refrigerant flow passages 20j and 20e, and is sucked into the compressor 21. The refrigerant flowing through the refrigerant circuit 20 releases the heat in the outdoor heat exchanger 22 and absorbs the heat in the heat exchanger 14. When the air mixing damper 16 is opened during the cooling and dehumidification operation, the refrigerant also releases the heat into the radiator 15.

[0200] In this case, in the air conditioning unit 10, during the cooling operation, the interior fan 12 is operated to force air through the air flow passage 11, and the air undergoes heat exchange with the refrigerant in the heat exchanger 14 and is cooled. The temperature of the cooled air becomes the target air blowing temperature TAO of the air to be blown from the outlets 11c, 11d, and 11e to adjust the temperature of the vehicle interior to the target setting temperature Tset. Then, the air at the temperature TAO is blown into the vehicle interior.

[0201] Meanwhile, in the air conditioning unit 10, during the cooling and dehumidification operation, the interior fan 12 is operated to force air through the air flow passage 11. The air undergoes heat exchange with the refrigerant that absorbs heat in the heat exchanger 14, and is thus cooled and dehumidified. The air dehumidified in the heat exchanger 14 undergoes heat exchange with the refrigerant that releases heat in the radiator 15, and is thus heated. As a result, the air is blown into the vehicle interior at the target air blowing temperature TAO.

[0202] During the heating operation, in the refrigerant circuit 20, the flow passage of the three-way valve 24 is set to the side of the refrigerant flow passage 20d, the first solenoid valve 25a is opened, and the second to fourth solenoid valves 25b to 25d are closed; and the compressor 21 is operated. By this measure, as shown in Fig. 31, the refrigerant discharged from the compressor 21 passes in this order through: 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 20e, and is sucked into the compressor 21. The refrigerant flowing through the refrigerant circuit 20 releases the heat in the radiator 15 and absorbs the heat in the outdoor heat exchanger 22.

[0203] In this case, in the air conditioning unit 10, the interior fan 12 is operated to force the air to flow through the air flow passage 11. The flowing air does not undergo heat exchange with the refrigerant in the heat exchanger 14, but rather undergoes heat exchange with the refrigerant in the radiator 15 and is therefore heated. As a result, the air is blown into the vehicle interior at the target air blowing temperature TAO.

[0204] During the heating and dehumidifying operation, in the refrigerant circuit 20, the flow passage of the three-way valve 24 is set to the side of the refrigerant flow passage 20d; the first and third solenoid valves 25a and 25c are opened, and the second and fourth solenoid valves 25b and 25d are closed; and the compressor 21 is operated. By this measure, as shown in Fig. 32, the refrigerant discharged from the compressor 21 passes through, in this order: the refrigerant flow passage 20a; the radiator 15; and the refrigerant flow passages 20b and 20d. Part of the refrigerant flowing through the refrigerant flow passage 20d passes through, in this order: the outdoor heat exchanger 22; and the refrigerant flow passage 20e, and is sucked into the compressor 21. Meanwhile, the remaining refrigerant flowing through the refrigerant flow passage 20d passes through, in this order: the refrigerant flow passage 20g; the high-pressure side of the indoor heat exchanger 23; the refrigerant flow passage 20h; the heat exchanger 14; the refrigerant flow passage 20i; the low-pressure side of the indoor heat exchanger 23; and the refrigerant flow passages 20j and 20e, and is sucked into the compressor 21.The refrigerant flowing through the refrigerant circuit 20 releases the heat into the radiator 15 and absorbs the heat in the heat exchanger 14 and the outdoor heat exchanger 22.

[0205] In this case, in the air conditioning unit 10, the interior fan 12 is operated to force air through the airflow passage 11. The flowing air undergoes heat exchange with the refrigerant in the heat exchanger 14 and is thus cooled and dehumidified. A portion of the air dehumidified in the heat exchanger 14 undergoes heat exchange with the refrigerant in the radiator 15 and is heated. As a result, the air is blown into the vehicle interior at the target air blowing temperature TAO.

[0206] During the defrosting operation, in the refrigerant circuit 20, the flow passage of the three-way valve 24 is set to the side of the refrigerant flow passage 20d; the first and fourth solenoid valves 25a and 25d are opened, and the second and third solenoid valves 25b and 25c are closed; and the compressor 21 is operated. By this measure, as shown in Fig. 33, a portion of the refrigerant discharged from the compressor 21 passes through the refrigerant flow passage 20a, the radiator 15, and the refrigerant flow passages 20b and 20d, in this order, and flows into the outdoor heat exchanger 22. Meanwhile, the remaining 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 from 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 releases heat in the radiator 15 and absorbs heat at this time in the outdoor heat exchanger 22.

[0207] In this case, in the air conditioning unit 10, the interior fan 12 is operated to flow the air through the air flow passage 11. The flowing air does not undergo heat exchange with the refrigerant in the heat exchanger 14, but undergoes heat exchange with the refrigerant that releases heat in the radiator 15, and is therefore heated and then blown to the vehicle interior.

[0208] While the automatic switch of the operating part 50 is turned on, the control device 40 executes an operation switching control process to switch the operation between the cooling operation, the cooling and dehumidifying operation, the heating operation, the heating and dehumidifying operation, and the defrosting operation based on indoor and outdoor environmental conditions such as temperature.

[0209] The control device 40 switches the operation mode between the foot operation mode, the ventilation mode, and the two-level operation mode depending on the target air blowing temperature TAO during each operation switched by the operation switching control process. To be more specific, when the target air blowing temperature TAO is high, e.g., 40 degrees Celsius, the control device 40 sets the foot operation mode. Meanwhile, when the target air blowing temperature TAO is low, e.g., lower than 25 degrees Celsius, the control device sets the ventilation mode. Furthermore, when the target air blowing temperature TAO is the temperature between the temperature for the foot operation mode and the temperature for the ventilation mode, the control device 40 sets the two-level operation mode.

[0210] The control device 40 switches the operation mode of the outlets 11c, 11d and 11e using the outlet switching dampers 13b, 13c and 13d, and controls the opening of the air mixing damper 16 to adjust the temperature of the air blown from the outlets 11c, 11d and 11e to the target air blowing temperature TAO.

[0211] In addition, during the heating operation and the heating and dehumidification operation, the control device 40 executes a superheat control process to optimize the superheat of the refrigerant flowing out of the outdoor heat exchanger 22. The operation of the control device 40 for this process will now be described with reference to the Fig. The flowchart shown in Figure 34 explains this. (Step 81)

[0212] In step 81, the CPU sets a predetermined value A (e.g., 2 to 5 degrees Celsius) as the target superheat SHt when the operation is the superheat operation, and sets a value calculated based on the outside air temperature Tam and the target temperature Tet of the heat exchanger 14 as the target superheat SHt when the operation is the heating and dehumidifying operation. (Step S82)

[0213] In step S82, the CPU calculates a correction amount H for the target superheat SHt set in step S81 based on the temperature Te and the target temperature Tet of the heat exchanger 14. To be more specific, the CPU determines whether the temperature Te detected by the cooled air temperature sensor 44 is equal to or lower than a temperature (Tet-α) obtained by subtracting a predetermined temperature α from the target temperature Te. If it is determined that the temperature Te is Tet-α or lower, the CPU determines a correction amount H (H<0) to decrease the target superheat SHt. Otherwise, if it is determined that the temperature Te is higher than Tet-α, the CPU determines a correction amount H (H>0) to increase the target superheat SHt. (Step S83)

[0214] In step S83, the CPU calculates a corrected target superheat SHtc obtained by adding the correction amount H to the target superheat SHt. (Step S84)

[0215] In step S84, the CPU calculates the superheat SH of the refrigerant based on 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. (Step S85)

[0216] In step S85, the CPU controls the opening of the first expansion valve 27a based on the corrected target superheat SHtc and the superheat SH.

[0217] In this way, with the vehicle air conditioning device according to the present invention, the opening of the first expansion valve 27a is controlled based on the target superheat SHt and the refrigerant superheat SH. The target superheat SHt is assigned the predetermined value A during the heating operation, whereas during the heating and dehumidification operation, it is assigned the value based on the outside air temperature Tam and the target temperature Tet of the heat exchanger 14. The refrigerant superheat SH is calculated based on 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. Thus, by controlling the superheat SH of the refrigerant flowing out of the outdoor heat exchanger 22, it is possible to optimize the amount of heat absorbed in the outdoor heat exchanger 22 and therefore maintain the temperature Tr and the humidity Th of the vehicle interior in a good state.

[0218] Fig. Figure 35 shows Embodiment 7 of the present invention. Here, the same components are assigned the same numbers as in the above-described embodiments.

[0219] In the vehicle air conditioning device according to the present invention, the control device 40 executes a process as shown in the flowchart in Fig. 35, with the same configuration as Embodiment 6. (Step S91)

[0220] In step S91, when the operation is the heating operation, the CPU sets a predetermined value A (e.g., 2 to 5 degrees Celsius) as the target superheat SHt, and when the operation is the heating and dehumidifying operation, it sets a value calculated based on the outside air temperature Tam and the target temperature Tet of the heat exchanger 14 as the target superheat SHt. (Step S92)

[0221] In step S92, the CPU calculates a switchable setpoint EXVtgtFF for opening the first expansion valve 27a based on the target superheat SHt set in step S91. The switchable setpoint EXVtgtFF is calculated based on the outside air temperature Tam, a voltage BLV of the electric motor 12a for driving the indoor fan 12, and a rotational speed Nc of the electric motor 21a for driving the compressor 21 (EXVtgtFF = KaxTam+KbxBLV+KcxNc+d, where Ka, Kb, Kc, and d are preset fixed values). (Step S93)

[0222] In step S93, the CPU calculates a target value SHtgt responsive to the target superheat based on the target superheat SHt set in step S91.

[0223] The addressable setpoint SHtgtf is caused to respond to the setpoint superheat SHt with a first-order delay. (Step S94)

[0224] In step S94, the CPU calculates the superheat SH of the refrigerant based on 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. (Step S95)

[0225] In step S95, the CPU calculates a feedback set value EXVtgtFB for the opening of the first expansion valve 27a based on the responsive set value SHTtgtf calculated in step S93 and the refrigerant superheat SH calculated in step S94. The feedback setpoint EXVtgtFB is an output value of a proportional plus integral (PI) control calculated based on the responsive setpoint SHtgtf and the refrigerant superheat SH calculated in step S94 (EXVtgtFB = EXVtgtfbp + EXVtgtfbi, EXVtgtfbp = Kp x (SHtgtf - SH), EXVtgtfbi = EXVtgtfbi_n-1 + Kp / Tix(SHtgtf-SH), where Kp is a constant value as a proportional gain; Ti is an integral time; and EXVtgtfbi_n-1 is the previous value of EXVtgtfbi). (Step S96)

[0226] In step S96, the CPU controls the opening of the first expansion valve 27a based on the switchable setpoint EXVtgtFF calculated in step S92 and the feedback setpoint EXVtgtFB calculated in step S95.

[0227] As described above, with the vehicle air conditioning system according to the present invention, by controlling the superheat SH of the refrigerant flowing out of the outdoor heat exchanger 22, it is possible to optimize the amount of heat absorbed in the outdoor heat exchanger 22 in the same manner as in the above-described embodiment. Therefore, it is possible to maintain the indoor air temperature Tr and the indoor air humidity Th in a good state.

[0228] In addition, the switchable setpoint EXVtgtFF for opening the first expansion valve 27a is calculated based on the target superheat SHt. The setpoint SHtgtf responsive to the target superheat SHt is calculated. The feedback setpoint EXVtgtFB for opening the first expansion valve 27a is calculated based on the switchable setpoint SHtgtf and the refrigerant superheat SH. The opening of the first expansion valve 27a is controlled based on the switchable setpoint EXVtgtFF and the feedback setpoint EXVtgtFB. This measure makes it possible to improve the control performance of the indoor temperature Tr and indoor humidity Th.

[0229] Here, in the present embodiment, a configuration has been described in which the heat quantity of the air flowing through the air flow passage 11, which undergoes heat exchange with the refrigerant in the radiator 15, is used as the heat source for the heating operation, the heating and dehumidification operation, and the cooling and dehumidification operation. However, this is by no means limiting. If the heat quantity is insufficient, an auxiliary heat source may be provided. For example, in addition to the radiator 15, an electric heater may be provided in the air flow passage 11 as a heat source that can directly heat the air flow passage 11. In addition, a water heating circuit is formed across the inside and outside of the air flow passage 11 to heat the water flowing through the water heating circuit outside the air flow passage 11 and release the heat from the heated water into the air flow passage 11.

[0230] Additionally, a configuration was described in which the three-way valve 24 is used to switch between the refrigerant flow passages 20c and 20d. However, this is by no means limiting. Instead of the three-way valve 24, two solenoid valves can be used to switch between the refrigerant flow passages 20c and 20d. List of reference symbols

[0231] 10 Air conditioning unit; 14 Heat exchanger; 15 Radiator; 20 Refrigerant circuit; 20a to 20k Refrigerant flow passage; 20l Bypass flow passage; 21 Compressor; 22 Outdoor heat exchanger; 24 Three-way valve; 25a First solenoid valve; 25b Second solenoid valve; 25c Third solenoid valve, on-off valve; 25d Fourth solenoid valve; 25e Bypass solenoid valve; 26a to 26c First to third check valves; 27a First expansion valve; 27b Second expansion valve; 27c Electronic expansion valve; 40 Control device; 41 Outdoor air temperature sensor; 42 Indoor air temperature sensor; 43 Inlet temperature sensor; 44 Refrigerated air temperature sensor; 45 Heated air temperature sensor; 46 Interior humidity sensor; 47 Refrigerant temperature sensor; 48 Solar radiation sensor; 49 Speed ​​sensor; 50 Actuator; 51 Pressure sensor.

Claims

[1] Vehicle air conditioning device, comprising: a compressor (21) configured to compress and discharge a refrigerant; a radiator (15) provided in a vehicle interior and configured to release heat from the refrigerant; a heat exchanger (14) provided in the vehicle interior and configured to absorb the heat into the refrigerant; and an external heat exchanger (22) provided outside the vehicle interior and configured to release the heat from the refrigerant or to absorb the heat into the refrigerant, where the vehicle air conditioning system performs: a cooling operation to release the heat from the refrigerant discharged from the compressor (21) into the outdoor heat exchanger (22), decompress the refrigerant through a second expansion valve (27b), and absorb the heat in the heat exchanger (14) into the refrigerant; a cooling and dehumidifying operation to release the heat from the refrigerant discharged from the compressor (21) into the radiator (15) and the outdoor heat exchanger (22), decompress the refrigerant through the second expansion valve (27b), and absorb the heat in the heat exchanger (14) into the refrigerant; a heating operation to release the heat from the refrigerant discharged from the compressor (21) into the radiator (15), decompress the refrigerant through a first expansion valve (27a), and absorb the heat into the refrigerant in the outdoor heat exchanger (22); and a heating and dehumidifying operation to release the heat from the refrigerant discharged from the compressor (21) into the radiator (15), decompress a part of the refrigerant through the second expansion valve (27b), and absorb the heat in the heat exchanger (14) into the refrigerant, while a remaining refrigerant is decompressed by the first expansion valve (27a) and then the heat is absorbed in the outdoor heat exchanger (22) into the refrigerant, wherein the vehicle air conditioning device further comprises: an on-off valve (25c) provided in a refrigerant flow passage (20g) for allowing the refrigerant to flow into the heat exchanger (14) and configured to be capable of opening and closing the refrigerant flow passage (20g); characterized by that the vehicle air conditioning system continues to have: a cooled air temperature sensor (44) configured to detect a temperature (Te) of air cooled in the heat exchanger (14); and a refrigerant flow restricting part configured to restrict the refrigerant from flowing into the heat exchanger (14) using the on-off valve (25c) when the evaporation temperature detected by the cooled air temperature sensor (44) is a predetermined temperature or lower during the heating and dehumidifying operation.

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