VEHICLE AIR CONDITIONING

Abstract

Vehicle air conditioning system (1), comprising: an airflow path (11) in which air supplied to a passenger compartment flows, a refrigerant circuit (20) with a compressor (21) that compresses the refrigerant, a heat sink (16) that causes the refrigerant to release heat, and a heat sink (15) that causes the refrigerant to absorb heat. and an external heat exchanger (22) which is provided outside the passenger compartment and causes the refrigerant to release or absorb heat, an auxiliary heating section (30) comprising a heat transfer fluid heating device (32) which heats a heat transfer fluid, and includes an airflow path internal heat exchanger (34) which is provided on the airflow path (11) and causes the heat transfer medium to release heat, and in which the heat transfer medium heated at the heat transfer medium heating device (32) circulates, a heat transfer fluid-refrigerant heat exchanger (27) which causes the refrigerant flowing from a first refrigerant flow path (20c) formed between the external heat exchanger (22) and the heat sink (15) to absorb heat and thus carry out a heat exchange with the heat transfer fluid, an air conditioning operation performance evaluation section designed to assess whether air conditioning operation is possible using the refrigerant circuit (20), an auxiliary heating operation performance evaluation section, which is set up to assess whether an auxiliary heating function is added, an operating control section which is configured, when the air conditioning operation performance evaluation section determines that air conditioning operation using the refrigerant circuit (20) is possible, and the auxiliary heating operation performance evaluation section determines that adding the auxiliary heating function is necessary, to operate the heat transfer fluid heating device (32) while limiting its output power to or below a specified power limit value, and an outdoor air temperature assessment section designed to assess whether the outdoor air temperature is at or below a pre-set temperature threshold, wherein the refrigerant circuit (20) comprises a third refrigerant flow path (20e) which branches off from a second refrigerant flow path (20b) formed between the heat sink (16) and the external heat exchanger (22) and is connected to the first refrigerant flow path (20c) bypassing the external heat exchanger (22), wherein the auxiliary heating section (30) includes a first heat transfer fluid circuit (30b), which allows the heat transfer fluid heated at the heat transfer fluid heating device (32) to flow back into the heat transfer fluid heating device (32) via the heat transfer fluid-refrigerant heat exchanger (27), and comprises a second heat transfer fluid circuit (30c) which allows the heat transfer fluid heated at the heat transfer fluid heating device (32) to flow into the heat transfer fluid-refrigerant heat exchanger (27), allows the heat transfer fluid flowing out of the heat transfer fluid-refrigerant heat exchanger (27) to flow into the heat exchanger (34) within the airflow path, and allows the heat transfer fluid flowing out of the heat exchanger (34) within the airflow path to flow back into the heat transfer fluid heating device (32), wherein the operating control section is designed to circulate the heat transfer fluid in the first heat transfer fluid circuit (30b) and to effect a heat exchange at the heat transfer fluid-refrigerant heat exchanger (27) between the heat transfer fluid circulating in the first heat transfer fluid circuit (30b) and the refrigerant flowing into the heat transfer fluid-refrigerant heat exchanger (27) through the third refrigerant flow path (20e).

Description

TECHNICAL AREA

[0001] The present invention relates to a vehicle air conditioning system applicable to a vehicle such as an electric vehicle or a hybrid vehicle. STATE OF THE ART

[0002] For several years now, the automotive industry has been driving research and development for vehicles such as hybrid vehicles, plug-in hybrid vehicles, electric vehicles, and similar vehicles powered by an electric motor (hereinafter collectively referred to as "electric vehicles") in order to reduce energy consumption and thus lower CO2 emissions. An air conditioning system installed in an electric vehicle uses a heat pump circuit, which allows for heating operation when it cannot utilize waste heat from a combustion engine during electric driving.

[0003] For example, in JP 2016-107 745 A, an air conditioning system that uses a heat pump system is disclosed, comprising a refrigerant circuit in which a compressor that compresses and discharges a refrigerant, a heat sink provided in a passenger compartment and serving as a condenser which causes heat exchange with the refrigerant, a heat sink provided in the passenger compartment and serving as an evaporator which causes the refrigerant to absorb heat, and an external heat exchanger provided outside the passenger compartment and serving as an evaporator which causes the refrigerant to absorb heat from blown-in outside air, or as a condenser which causes it to release heat, are connected together.The air conditioning system can switch between different climate control modes, including a "heating mode" in which refrigerant discharged from the compressor releases heat at the heat sink and the refrigerant that has discharged heat at the heat sink absorbs heat at the external heat exchanger, a "cooling mode" in which refrigerant discharged from the compressor releases heat at the external heat exchanger and absorbs heat at the heat sink, a "dehumidifying heating mode" in which refrigerant discharged from the compressor releases heat at the heat sink and the refrigerant that has discharged heat at the heat sink absorbs heat at the heat sink and the external heat exchanger, and a "dehumidifying cooling mode" in which refrigerant discharged from the compressor releases heat at the heat sink and the external heat exchanger absorbs heat at the heat sink.

[0004] The air conditioning system from JP 2016-107 745 A includes, as a means of implementing the auxiliary heating function at low outside temperatures (e.g., 0 °C or below), a heat transfer circuit comprising a circulation pump, a heat transfer heating device (ECH), and a heat transfer-to-air heat exchanger. The heat transfer circuit is located on the upstream side of the heat sink in an airflow path through which air supplied to the passenger compartment flows. The heat transfer circuit supports heating operation by heating the heat transfer fluid circulated by the circulation pump through the heat transfer heating device, with the heat transfer-to-air heat exchanger in the airflow path acting as the heating element. BRIEF SUMMARY OF THE INVENTIONAL TASKS OF THE INVENTION

[0005] However, the problem with the state-of-the-art air conditioning system, which includes the device from JP 2016-107 745 A, is that at extremely low temperatures, such as an outside air temperature below -15 °C, the flow rate of the refrigerant being compressed at the compressor decreases as its density drops, and the compressor's performance decreases significantly, making normal heating operation impossible.

[0006] If, in a state-of-the-art air conditioning system, a heating element of the heat transfer fluid heating device is operated at maximum output power (100%), its service life is reduced and it can become a source of malfunction, which is why its operation is restricted to approximately 50% of the maximum output power.

[0007] At extremely low outside air temperatures, normal heating operation is therefore not possible with state-of-the-art air conditioning systems, and since the output power of the heat transfer fluid heating device is limited, the heating output is low, which makes it difficult to keep the environment in the passenger compartment comfortable.

[0008] The present invention is based on the objective of solving the problems of the prior art and providing a vehicle air conditioning system that largely prevents a reduction in the service life of the heat transfer fluid heating device and can thereby increase the heating output. SOLUTION OF THE TASKS

[0009] To achieve the aforementioned objective, a vehicle air conditioning system according to the present invention comprises an airflow path in which air supplied to a passenger compartment flows, a refrigerant circuit with a compressor that compresses refrigerant, a heat sink that causes the refrigerant to release heat, a heat sink that causes the refrigerant to absorb heat, and an external heat exchanger provided outside the passenger compartment that causes the refrigerant to release or absorb heat, an auxiliary heating section comprising a heat transfer fluid heating device that heats a heat transfer fluid, and an airflow path-internal heat exchanger provided at the airflow path that causes the heat transfer fluid to release heat, and in which the heat transfer fluid heated by the heat transfer fluid heating device circulates, and a heat transfer fluid-refrigerant heat exchanger that causesthat the refrigerant flowing from a first refrigerant flow path formed between the external heat exchanger and the heat sink absorbs heat and thus performs a heat exchange with the heat transfer fluid; an air conditioning operation performance evaluation section that assesses whether air conditioning operation is possible using the refrigerant circuit; an auxiliary heating operation performance evaluation section that assesses whether an auxiliary heating function is added; and an operation control section that, if the air conditioning operation performance evaluation section determines that air conditioning operation is possible using the refrigerant circuit and the auxiliary heating operation performance evaluation section determines that adding the auxiliary heating function is necessary, operates the heat transfer fluid heating device while limiting its output power to or below a specified power limit value.

[0010] Advantageously, the power limit value of the vehicle air conditioning system can be set to 50% or less of the maximum output power of the heat transfer fluid heating device.

[0011] According to the invention, the vehicle air conditioning system comprises an outside air temperature assessment section that assesses whether the outside air temperature is at or below a preset temperature threshold, wherein the refrigerant circuit comprises a third refrigerant flow path that branches off from a second refrigerant flow path formed between the heat sink and the external heat exchanger and is connected to the first refrigerant flow path, bypassing the external heat exchanger, wherein the auxiliary heating section comprises a first heat transfer fluid circuit that allows the heat transfer fluid heated at the heat transfer fluid heating device to flow back into the heat transfer fluid heating device via the heat transfer fluid-refrigerant heat exchanger, and a second heat transfer fluid circuit that allows the heat transfer fluid heated at the heat transfer fluid heating device to flow into the heat transfer fluid-refrigerant heat exchanger.The heat transfer fluid flowing from the heat transfer fluid-refrigerant heat exchanger is allowed to flow into the heat exchanger within the airflow path, and the heat transfer fluid flowing from the heat exchanger within the airflow path is allowed to flow back into the heat transfer fluid heating device, wherein the operating control section, in the event that the outside air temperature assessment section determines that the outside air temperature is at or below the temperature threshold, allows the heat transfer fluid to circulate in the first heat transfer fluid circuit and can effect a heat exchange at the heat transfer fluid-refrigerant heat exchanger between the heat transfer fluid circulating in the first heat transfer fluid circuit and the refrigerant flowing into the heat transfer fluid-refrigerant heat exchanger through the third refrigerant flow path.

[0012] Advantageously, in the case of the vehicle air conditioning system, the operating control section can, in the event that the air conditioning operation performance evaluation section determines that air conditioning operation using the refrigerant circuit is possible but no air conditioning operation takes place, or determines that no air conditioning operation using the refrigerant circuit is possible, override the power limitation of the heat transfer fluid heating device by the power limitation value and cause the heat transfer fluid to be heated, and allow the heat transfer fluid to circulate in the second heat transfer fluid circuit and heat the air flowing in the airflow path. EFFECTS OF THE INVENTION

[0013] According to the present invention, a reduction in the service life of the heat transfer fluid heating device can be largely prevented, while simultaneously increasing the heating power. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] They show: Fig. 1 a schematic configuration view of a vehicle air conditioning system of an embodiment of the present invention; Fig. 2 a block diagram of a tax system; Fig. 3 a schematic diagram of the vehicle air conditioning system, illustrating a flow path of refrigerant and heat transfer fluid in a first auxiliary heating mode; Fig. 4 A schematic diagram of the vehicle air conditioning system, illustrating a flow path of the refrigerant and the heat transfer fluid in a second normal auxiliary heating mode; Fig. 5 A schematic diagram of the vehicle air conditioning system, illustrating the flow path of the refrigerant and heat transfer fluid in a low-temperature auxiliary heating mode; Fig. 6 a schematic diagram of the vehicle air conditioning system, illustrating a flow path of the heat transfer fluid in an emergency auxiliary heating mode; and Fig. 7. A flowchart illustrating the content of processes when selecting the heating mode. DESCRIPTION OF THE EXECUTION FORMS

[0015] In the following, an embodiment of the present invention is described with reference to the figures.

[0016] The embodiment shown herein represents a concrete example to illustrate the technical concept of the present invention and is not intended to limit the present invention. Further embodiments, exemplary embodiments, and implementation techniques that a person skilled in the art can carry out without deviating from the scope of the present invention are all within the scope and teachings of the invention and are also included in the scope of the inventions set forth in the claims and their equivalents.

[0017] In the drawings accompanying this description, dimensions, vertical and horizontal dimensional ratios, shapes and the like may be modified or schematically represented to facilitate illustration and understanding, and they are merely examples and are not intended to limit the interpretation of the present invention.

[0018] A vehicle air conditioning system 1 of the present invention is applied to an electric vehicle that is capable of being driven by the driving force of an electric motor, such as a hybrid vehicle, a plug-in hybrid vehicle, an electric vehicle or the like.

[0019] In this description, the "temperature control target device" is an on-board device (on-board heat generation device) installed in the electric vehicle and used while driving or propelling the vehicle. It constitutes a heat source capable of generating heat during operation, such as a battery, an electric motor, an inverter, or an ECU (electronic control unit), and its temperature is regulated by cooling or heating to achieve a suitable operating temperature. In this embodiment, the description uses the example of a cooled battery as the temperature control target device 100. Overview of the device

[0020] Fig. Figure 1 shows a view of the structure of the vehicle air conditioning system 1 according to the present embodiment.

[0021] As in Fig. 1 or Fig. As shown in Figure 2, the vehicle air conditioning system 1 is a device that performs air conditioning (heating, cooling, dehumidifying, and ventilation) of a vehicle's passenger compartment. The vehicle air conditioning system 1 comprises an air conditioning unit 10 located inside the passenger compartment, a refrigerant circuit 20 located both inside and outside the passenger compartment, an auxiliary heating section 30 that cools a temperature control target device 100, and a control device 40 that controls the operation of the individual sections of the vehicle air conditioning system 1. air conditioning unit

[0022] The air conditioning unit 10 has an airflow path 11 for allowing air to flow into the interior of the passenger compartment.

[0023] On one end side of the airflow path 11, intake openings 12 are provided, which have an outside air intake opening 12a to allow air from outside the passenger compartment to flow into the airflow path 11, and an inside air intake opening 12b to allow air from inside the passenger compartment to flow into the airflow path 11.

[0024] At one end of the airflow path 11, an intake opening switching flap 13 is provided, which can open one of the external air intake openings 12a or 12b and close the other. Also at one end of the airflow path 11, an internal fan 14, such as a flat fan, is provided to allow air to flow from one end to the other of the airflow path 11.

[0025] At the other end of the airflow path 11, discharge openings are provided through which the air flowing through the airflow path 11 is discharged at specified locations in the passenger compartment. The discharge openings include a footwell discharge opening (not shown) to blow air onto an occupant's feet, a vent opening (not shown) to blow air onto the occupant's upper body, and a windshield discharge opening (not shown) to blow air onto a surface of the windshield in the passenger compartment. Discharge switching flaps (not shown) are provided to change the discharge direction of the air from the discharge openings.

[0026] On the downstream side of the internal fan 14 along the airflow path 11, a heat sink 15 is provided for cooling and dehumidifying the air flowing through the airflow path 11. On the downstream side of the heat sink 15 along the airflow path 11, a heat drain 16 is provided for heating the air flowing through the airflow path 11.

[0027] The heat sink 16 is arranged on one side orthogonal to the airflow path 11, and on the other side orthogonal to the airflow path 11, a bypass airflow path 11a is formed, which leads around the heat sink 16. An air mixing damper 17 is provided between the heat sink 15 and the heat sink 16 on the airflow path 11 to regulate the proportion of air flowing into the heat sink 16 and air flowing through the bypass airflow path 11a from the air flowing through the heat sink 15. The installation location of the heat sink 16 is not limited to the airflow path 11 and can also be located outside the air conditioning unit 10.

[0028] Depending on the selected operating mode (air conditioning mode, unit cooling mode), the air mixing flap 17 closes the upstream side of one of the bypass flow path 11a and the heat sink 16 and opens the other, or it regulates the degree of opening of the upstream side of the heat sink 16 and opens both the bypass flow path 11a and the heat sink 16. The temperature of the blown air from the air conditioning unit 10 into the passenger compartment can be regulated by adjusting the opening position of the air mixing flap 17. Refrigerant circuit

[0029] The refrigerant circuit 20 comprises the heat sink 15 and the heat sink 16, a compressor 21 for compressing refrigerant, an external heat exchanger 22 for heat exchange between the refrigerant and air outside the passenger compartment, expansion valves 23 whose degree of opening is adjustable between fully closed and fully open (first expansion valve 23a, second expansion valve 23b and third expansion valve 23c), electromagnetic valves 24 for opening and closing the refrigerant flow path (first electromagnetic valve 24a, second electromagnetic valve 24b), check valves 25 for restricting the flow direction of the refrigerant in the refrigerant flow path (first check valve 25a, second check valve 25b), an accumulator 26 that separates gaseous and liquid refrigerant and causes the compressor 21 to draw in gaseous refrigerant,and a heat transfer fluid-refrigerant heat exchanger 27, which performs a heat exchange between the refrigerant flowing in the refrigerant circuit 20 and the heat transfer fluid flowing in the auxiliary heating section 30. The individual sections that form the refrigerant circuit 20 are connected by refrigerant flow paths 20a-20g, which are formed by refrigerant lines such as aluminum or copper lines, so that the refrigerant can circulate. For example, R-134a or the like is used as the refrigerant flowing in the refrigerant circuit 20.

[0030] The external heat exchanger 22 is located outside the passenger compartment in an engine compartment or the like, such that the airflow direction for heat exchange with the refrigerant is the front-to-back direction of the vehicle. An external fan 22a is provided in the area of ​​the external heat exchanger 22 to allow air from outside the passenger compartment to flow in a front-to-back direction when the vehicle is stationary.

[0031] In the refrigerant circuit 20, a refrigerant flow path 20a is formed, which connects the refrigerant discharge side of the compressor 21 and the refrigerant inlet side of the heat sink 16, and a refrigerant flow path 20b (corresponding to the "second refrigerant flow path" of the claims) is formed, which connects the refrigerant outlet side of the heat sink 16 and the refrigerant inlet side of the external heat exchanger 22. The first expansion valve 23a is provided on the refrigerant flow path 20b.

[0032] In the refrigerant circuit 20, a refrigerant flow path 20c (corresponding to the "first refrigerant flow path" of the claims) is formed, which connects the refrigerant outlet side of the external heat exchanger 22 and the refrigerant inlet side of the heat sink 15. The first check valve 25a and the second expansion valve 23b are provided on the refrigerant flow path 20c, starting from the external heat exchanger 22, in this order.

[0033] In the refrigerant circuit 20, a refrigerant flow path 20d is formed, which connects the refrigerant outlet side of the heat sink 15 and the refrigerant intake side of the compressor 21. The second check valve 25b and the accumulator 26 are provided along the refrigerant flow path 20d, starting from the heat sink 15, in this order.

[0034] In the refrigerant circuit 20, a refrigerant flow path 20e is formed between the heat sink 16 and the first expansion valve 23a on refrigerant flow path 20b. This path bypasses the external heat exchanger 22 and connects the first check valve 25a and the second expansion valve 23b on refrigerant flow path 20c. The first electromagnetic valve 24a is located on refrigerant flow path 20e.

[0035] In the refrigerant circuit 20, a refrigerant flow path 20f (corresponding to the "fifth refrigerant flow path" of the claims) is formed between the external heat exchanger 22 and the first check valve 25a on the refrigerant flow path 20c, which connects the heat sink 15 and the second check valve 25b on the refrigerant flow path 20d. The second electromagnetic valve 24b is provided in the refrigerant flow path 20f.

[0036] In the refrigerant circuit 20, a refrigerant flow path 20g is formed between the first check valve 25a and the second expansion valve 23b. This path is connected to the refrigerant inlet side of the heat transfer fluid-refrigerant heat exchanger 27 and, from the refrigerant outlet side of the heat transfer fluid-refrigerant heat exchanger 27, connects the second check valve 25b and the accumulator 26 on refrigerant flow path 20d. The third expansion valve 23c is provided on the refrigerant inlet side of the heat transfer fluid-refrigerant heat exchanger 27 on refrigerant flow path 20g. Refrigerant flow path 20g is designed to allow refrigerant diverted from refrigerant flow path 20c to flow through the heat transfer fluid-refrigerant heat exchanger 27 and then to refrigerant flow path 20d.When refrigerant 20 flows into the refrigerant flow path 20g in the refrigerant circuit, the refrigerant undergoes a pressure reduction through the third expansion valve 23c and flows into the heat transfer fluid-refrigerant heat exchanger 27. The refrigerant flowing into the heat transfer fluid-refrigerant heat exchanger 27 evaporates in the heat transfer fluid-refrigerant heat exchanger 27 and is subjected to heat exchange with the heat transfer fluid flowing in the auxiliary heating section 30. Auxiliary heating section

[0037] The auxiliary heating section 30 is designed by a circuit to circulate the heat transfer medium (for example, a liquid such as water, a refrigerant such as HFO-1234yf or coolant or air) to the battery, which is the temperature control target device 100, and to regulate the temperature of the temperature control target device 100.

[0038] The auxiliary heating section 30 comprises a circulation pump 31 serving as a circulation device, which circulates the heat transfer medium, a heat transfer medium heating device (ECH) 32, which heats the heat transfer medium, a direction reversing valve 33 such as a three-way valve, which changes the flow direction of the heat transfer medium circulating in the auxiliary heating section 30, and an airflow path-internal heat exchanger (heating core) 34, which is provided in the direction of the air flowing in the air conditioning unit 10 between the heat sink 15 and the heat drain 16 and carries out a heat exchange between the heat transfer medium and air.

[0039] In the auxiliary heating section 30, a heat transfer circuit 30a is formed by connecting the circulation pump 31, the heat transfer fluid heating device 32, the heat transfer fluid-refrigerant heat exchanger 27, the temperature control target device 100 and the air flow path internal heat exchanger 34 in a ring shape using heat transfer fluid lines, in which the flow path of the heat transfer fluid can be switched by means of the direction switching valve 33.

[0040] In the heat transfer circuit 30a in Fig. 1. The heat transfer fluid lines connect the discharge side of the circulation pump 31 and the heat transfer fluid inlet side of the heat transfer fluid heating device 32, the heat transfer fluid outlet side of the heat transfer fluid heating device 32 and the heat transfer fluid inlet side of the heat transfer fluid-refrigerant heat exchanger 27, and the heat transfer fluid outlet side of the heat transfer fluid-refrigerant heat exchanger 27 and the heat transfer fluid inlet side of the temperature control target device 100, as well as the heat transfer fluid outlet side of the temperature control target device 100 and the heat transfer fluid suction side (inlet side) of the circulation pump 31, thereby forming a first heat transfer fluid circuit 30b.In the first heat transfer circuit 30b, the heat transfer fluid flows from the circulation pump 31 sequentially from the circulation pump 31 to the heat transfer fluid heating device 32 → heat transfer fluid-refrigerant heat exchanger 27 → reversing valve 33 → temperature control target device 100 and then back to the circulation pump 31.

[0041] In the heat transfer circuit 30a in Fig. Furthermore, the heat transfer fluid outlet side of the heat transfer fluid-refrigerant heat exchanger 27 and the heat transfer fluid inlet side of the airflow path-integrated heat exchanger 34, as well as the heat transfer fluid outlet side of the airflow path-integrated heat exchanger 34 and the heat transfer fluid intake side of the circulation pump 31, are connected via the heat transfer fluid lines and the reversing valve 33, thus forming a second heat transfer fluid circuit 30c. In the second heat transfer fluid circuit 30c, the heat transfer fluid flows from the circulation pump 31 sequentially from the circulation pump 31 to the heat transfer fluid heating device 32 → heat transfer fluid-refrigerant heat exchanger 27 → reversing valve 33 → airflow path-integrated heat exchanger 34 and then back to the circulation pump 31. Control device

[0042] The control device 40 is formed by an ECU (electronic control unit) which is a known microcomputer comprising a CPU, ROM, RAM, and the like, along with peripheral circuitry. The control device 40 performs various calculations and processing operations based on a control program stored in the ROM and controls the operation of various control target objects connected to an output interface.

[0043] With the control device 40, as in Fig. Figure 2 shows an outside air temperature sensor 41 for measuring the temperature outside the passenger compartment, an inside air temperature sensor 42 for measuring the temperature inside the passenger compartment, a heat sink temperature sensor 43 for measuring the temperature of the heat sink 15 (temperature of the air flowing through the heat sink 15, temperature of the heat sink 15 itself, or temperature of the refrigerant immediately after exiting the heat sink 15), a heat sink temperature sensor 44 for measuring the temperature of the heat sink 16 (temperature of the air flowing through the heat sink 16, temperature of the heat sink 16 itself, or temperature of the refrigerant immediately after exiting the heat sink 16), an inside air humidity sensor 45 for measuring the humidity in the passenger compartment, and an outlet air temperature sensor 46 for measuring the temperature of the air blown into the passenger compartment from the outlet openings.a heat sink pressure sensor 47 for detecting the refrigerant pressure of the heat sink 15 (pressure of the refrigerant in the heat sink 15 or pressure of the refrigerant immediately after exiting the heat sink 15), a heat drain pressure sensor 48 for detecting the refrigerant pressure of the heat drain 16 (pressure of the refrigerant in the heat drain 16 or pressure of the refrigerant immediately after exiting the heat drain 16), a discharge pressure sensor 49 for detecting the discharge refrigerant pressure of the compressor 21, a compressor temperature sensor 50 for detecting the temperature of the refrigerant drawn into the compressor 21 and of the refrigerant discharged from it, an intake pressure sensor 51 for detecting the refrigerant intake pressure of the compressor 21,a temperature sensor 52 of the external heat exchanger for detecting the temperature of the external heat exchanger 22 (temperature of the external heat exchanger 22 itself or temperature of the refrigerant immediately after exiting the external heat exchanger 22), a pressure sensor 53 of the external heat exchanger for detecting the refrigerant pressure of the external heat exchanger 22 (pressure of the refrigerant in the external heat exchanger 22 or pressure of the refrigerant immediately after exiting the external heat exchanger 22), a temperature sensor 54 of the airflow path internal heat exchanger for detecting the temperature of the airflow path internal heat exchanger 34 (temperature of the airflow path internal heat exchanger 34 itself, temperature of the heat transfer fluid exiting the airflow path internal heat exchanger 34 or temperature of the heat transfer fluid entering the airflow path internal heat exchanger 34),A light incidence sensor 55, of a photosensor type, for detecting the amount of incident light, a speed sensor 56 for detecting the vehicle speed, a device temperature sensor 57 for detecting the temperature of the temperature control target device 100 (temperature of the temperature control target device 100 itself, temperature of the heat transfer fluid exiting the temperature control target device 100, or temperature of the heat transfer fluid entering the temperature control target device 100), and an adjustment control section 58 for making adjustments regarding the set temperature in the passenger compartment or the operating contents of the air conditioning system by the occupant are connected. The aforementioned sensors are installed at positions in the passenger compartment (or outside of it) where they can acquire the information of their detection object.

[0044] The control device 40 also includes, as described in Fig. 2 shown, the internal fan 14, the air mixing flap 17, the compressor 21, the external fan 22a, the expansion valves 23 (first expansion valve 23a to third expansion valve 23c), the electromagnetic valves 24 (first electromagnetic valve 24a, second electromagnetic valve 24b), the heat transfer fluid heating device 32 and the direction switching valve 33 connected.

[0045] The control device 40 controls the operation of the elements connected to it based on the information acquired by the sensors and the operating signals from the setting control section 58. When a setting command for the operating mode is entered from the setting control section 58, the control device 40 also controls the operation of the elements such that an air conditioning mode is executed as the operating mode, in which the air conditioning unit 10 and the refrigerant circuit 20 are operated and the air conditioning of the passenger compartment is managed, and an auxiliary heating mode is executed, in which the heating mode set as the air conditioning mode is operated with the addition of an auxiliary heating function.

[0046] When the auxiliary heating mode is executed and the control device 40 determines that air conditioning operation using the refrigerant circuit 20 is possible, it also initiates operation in which the output power of the heat transfer fluid heating device 32 is limited to or below a preset power limit value. The power limit value serves to prevent a reduction in service life by operating the heat transfer fluid heating device 32 at maximum output power and, although it also depends on the device capacity of the heat transfer fluid heating device 32, can be set to approximately 50% or less of the maximum output power.

[0047] Furthermore, when executing the auxiliary heating mode, the control device 40 can only cancel the power output of the heat transfer fluid heating device 32 according to the power limit value and allow operation up to the maximum output power if it is judged that air conditioning operation using the refrigerant circuit 20 is possible, but no air conditioning operation is taking place, or air conditioning operation using the refrigerant circuit 20 is not possible.

[0048] The control device 40 assesses whether air conditioning operation is possible using the refrigerant circuit 20 by comprehensively considering the outside air temperature, the temperature of the refrigerant drawn in by the compressor 21, the discharge pressure of the compressor 21, and similar factors. If the compressor 21 is malfunctioning and not operating, or if, for example, the refrigerant temperature is too low and the compressor 21's performance drops drastically, the control device 40 determines that air conditioning operation using the refrigerant circuit 20 is not possible (or does not occur) in order to prevent damage to the compressor 21.

[0049] Next, the air conditioning mode is described, which is an operating mode of the vehicle air conditioning system 1 according to the present embodiment.

[0050] The climate control mode is a mode for regulating and managing the temperature / humidity control and similar aspects of the passenger compartment and includes a cooling mode in which cooling is performed to lower the temperature of the passenger compartment, a dehumidifying cooling mode in which dehumidifying cooling is performed to lower the humidity of the passenger compartment and simultaneously lower the temperature, a heating mode in which heating is performed to raise the temperature of the passenger compartment, and a dehumidifying heating mode in which dehumidifying heating is performed to lower the humidity of the passenger compartment and simultaneously raise the temperature. Cooling mode

[0051] In cooling mode, the internal fan 14 of the air conditioning unit 10 is operated, and the opening degree of the air mixing flap 17 is adjusted so that no air flows in on the side of the heat sink 16. In the refrigerant circuit 20, the compressor 21 is operated in a state in which the first expansion valve 23a is fully open, the second expansion valve 23b is open to a defined degree, and the first electromagnetic valve 24a and the second electromagnetic valve 24b are closed.

[0052] The refrigerant flowing in the refrigerant circuit 20 therefore flows, after being discharged from the compressor 21, through the heat sink 16 and the first expansion valve 23a into the external heat exchanger 22. The refrigerant flowing into the external heat exchanger 22 is cooled and condenses by outside air blown towards it by the external fan 22a.

[0053] The refrigerant flowing from the external heat exchanger 22 passes through the first check valve 25a and reaches the second expansion valve 23b, where its pressure is reduced. It then flows into the heat sink 15 and evaporates. The refrigerant flowing from the heat sink 15 then passes through the second check valve 25b into the accumulator 26, where the gas and liquid phases are separated, and is then drawn in by the compressor 21. The refrigerant circulates in this way within the refrigerant circuit 20.

[0054] The air flowing through the airflow path 11 undergoes a heat exchange with the refrigerant, which absorbs heat at the heat sink 15, is thereby cooled to the target discharge temperature and is blown into the passenger compartment. Dehumidification cooling mode

[0055] In dehumidifying cooling mode, the opening degree on the air conditioning unit 10 is set such that air is blown through both the bypass flow path 11a and the air mixing flap 17. In the refrigerant circuit 20, the compressor 21 is operated in a state in which the first expansion valve 23a is fully open, the second expansion valve 23b is open to a defined degree, and the first electromagnetic valve 24a and the second electromagnetic valve 24b are closed.

[0056] The refrigerant flowing in the refrigerant circuit 20, after being discharged from the compressor 21, flows into the heat sink 16, undergoes heat exchange with the air in the airflow path 11, which extracts heat and cools it, and condenses. When the refrigerant flowing from the heat sink 16 reaches the first expansion valve 23a, its pressure is reduced and it then flows into the external heat exchanger 22. The refrigerant flowing into the external heat exchanger 22 is cooled by outside air blown towards it by the external fan 22a and condenses.

[0057] The refrigerant flowing from the external heat exchanger 22 passes through the first check valve 25a and reaches the second expansion valve 23b, where its pressure is reduced. It then flows into the heat sink 15 and evaporates. The refrigerant flowing from the heat sink 15 then passes through the second check valve 25b into the accumulator 26, where the gas and liquid phases are separated, and is then drawn in by the compressor 21. The refrigerant circulates in this way within the refrigerant circuit 20.

[0058] The air flowing in the airflow path 11 undergoes a heat exchange with the refrigerant, which absorbs heat in the heat sink 15, and is thereby cooled and dehumidified, reheated by heat exchange with the refrigerant, which releases heat at the heat drain 16, and regulated to a target discharge temperature and blown into the passenger compartment. Heating mode

[0059] In heating mode, the internal fan 14 of the air conditioning unit 10 is operated, and the opening degree of the air mixing flap 17 is adjusted so that the air is blown towards the heat sink 16. In the refrigerant circuit 20, the compressor 21 is operated in a state in which the first expansion valve 23a is set to a defined opening degree below full opening, the second expansion valve 23b and the first electromagnetic valve 24a are closed, and the second electromagnetic valve 24b is fully open.

[0060] The refrigerant flowing in the refrigerant circuit 20, after being discharged from the compressor 21, flows into the heat sink 16, undergoes heat exchange with the air in the airflow path 11, which extracts heat and cools it, and condenses. When the refrigerant flowing from the heat sink 16 reaches the first expansion valve 23a, its pressure is reduced and it then flows into the external heat exchanger 22. The refrigerant flowing into the external heat exchanger 22 evaporates and absorbs heat from the air blown in by the external fan 22a.

[0061] The refrigerant flowing from the external heat exchanger 22 passes through the second electromagnetic valve 24b and the second check valve 25b into the accumulator 26, where the gas and liquid phases are separated, and is then drawn in by the compressor 21. The refrigerant thus circulates in the refrigerant circuit 20.

[0062] The air flowing in the airflow path 11 undergoes a heat exchange with the refrigerant, which releases heat in the heat sink 16, and is thereby heated and regulated to the target discharge temperature and blown into the passenger compartment. Dehumidification heating mode

[0063] The dehumidification heating mode includes a first dehumidification heating mode and a second dehumidification heating mode. First dehumidification heating mode

[0064] In the first dehumidification heating mode, the internal fan 14 of the air conditioning unit 10 is operated and its opening degree is set such that air is blown through both the bypass flow path 11a and the air mixing flap 17. In the refrigerant circuit 20, the compressor 21 is operated in a state in which the first expansion valve 23a and the second expansion valve 23b are each set to a defined opening degree below full opening, and the first electromagnetic valve 24a and the second electromagnetic valve 24b are closed.

[0065] The refrigerant flowing in the refrigerant circuit 20, after being discharged from the compressor 21, flows into the heat sink 16, undergoes heat exchange with the air in the airflow path 11, which extracts heat and cools it, and condenses. When the refrigerant flowing from the heat sink 16 reaches the first expansion valve 23a, its pressure is reduced and it then flows into the external heat exchanger 22. The refrigerant flowing into the external heat exchanger 22 evaporates and absorbs heat from the air blown in by the external fan 22a.

[0066] The refrigerant flowing from the external heat exchanger 22 passes through the first check valve 25a and reaches the second expansion valve 23b, where its pressure is reduced. It then flows into the heat sink 15 and evaporates. The refrigerant flowing from the heat sink 15 then passes through the second check valve 25b into the accumulator 26, where the gas and liquid phases are separated, and is then drawn in by the compressor 21. The refrigerant circulates in this way within the refrigerant circuit 20.

[0067] The air flowing through the airflow path 11 undergoes a heat exchange with the refrigerant, which absorbs heat in the heat sink 15, and is thereby dehumidified and cooled, heated by heat exchange with the refrigerant, which releases heat in the heat drain 16, and regulated to the target discharge temperature and blown into the passenger compartment. Second dehumidification heating mode

[0068] In the second dehumidification heating mode, the internal fan 14 of the air conditioning unit 10 is operated and its opening degree is adjusted so that air is blown through both the bypass flow path 11a and the air mixing flap 17. In the refrigerant circuit 20, the compressor 21 is operated in a state in which the first expansion valve 23a is closed, the second expansion valve 23b is open to a defined degree, and the first electromagnetic valve 24a is open while the second electromagnetic valve 24b is closed.

[0069] The refrigerant flowing in the refrigerant circuit 20, after being discharged from the compressor 21, flows into the heat sink 16, undergoes heat exchange with the air in the airflow path 11, which extracts heat and cools it, and condenses. The refrigerant flowing from the heat sink 16 passes through the first electromagnetic valve 24a and reaches the second expansion valve 23b, where it experiences a pressure reduction, and then flows into the heat sink 15 and evaporates. The refrigerant flowing from the heat sink 15 then flows through the second check valve 25b into the accumulator 26, where the gas and liquid phases are separated, and is then drawn in by the compressor 21. The refrigerant circulates in this way within the refrigerant circuit 20.

[0070] The air flowing through the airflow path 11 undergoes a heat exchange with the refrigerant, which absorbs heat in the heat sink 15 and is thereby cooled, and is heated by heat exchange with the refrigerant, which releases heat in the heat drain 16, and regulated to the target discharge temperature and blown into the passenger compartment.

[0071] Next, with reference to Fig. Figures 3 to 6 describe an auxiliary heating mode implemented in the vehicle air conditioning system 1 according to the present embodiment. The arrows in the figures indicate the flow of the refrigerant or heat transfer fluid in the respective mode.

[0072] The auxiliary heating mode is a mode that switches to when the heating mode is set to air conditioning mode, if the control unit 40 determines that the auxiliary heating function is required. That is, if the user has set the heating mode and, according to the control unit 40, no auxiliary heating function is needed for heating operation, the heating mode is set; and if the auxiliary heating function is required, the auxiliary heating mode is activated.

[0073] The auxiliary heating mode includes a normal auxiliary heating mode and a low-temperature auxiliary heating mode, in which air conditioning operation using refrigerant circuit 20 is possible and which are set so that the auxiliary heating function supplements the operation in heating mode, and an emergency auxiliary heating mode, which is set when it is judged that air conditioning operation using the refrigerant circuit is possible but does not take place, or if air conditioning operation using refrigerant circuit 20 is not possible, for example if the outside air temperature is extremely low at below -15 °C or if there is a fault in the compressor 21 itself.

[0074] The control device 40 selects and sets the normal auxiliary heating mode and the low-temperature auxiliary heating mode based on the evaluation result of a comparison between the outside air temperature and a preset mode selection temperature threshold. The mode selection temperature threshold can, for example, be set to -10 °C when the output of the compressor 21 begins to decrease, whereby the control device 40 then sets the normal auxiliary heating mode when the outside air temperature is higher than -10 °C and then sets the low-temperature auxiliary heating mode when the outside air temperature is at or below -10 °C.

[0075] In the present embodiment, the auxiliary heating mode is described as a mode that is set under the condition that the heating mode is set, but the auxiliary heating mode can also be set in the dehumidification heating mode or independently without setting the heating mode. Normal auxiliary heating mode

[0076] The normal auxiliary heating mode is a mode that is set when the outside air temperature is, for example, 0 °C to -9 °C and therefore the auxiliary heating function is required. In this mode, the air flowing in the airflow path 11 is heated, and this heating is supplemented by the heat transfer fluid heated by the heat transfer fluid heating device 32. The normal auxiliary heating mode comprises a first normal auxiliary heating mode and a second normal auxiliary heating mode. In the normal auxiliary heating mode, the heat transfer fluid circulates in the second heat transfer fluid circuit 30c, such that it flows through the heat exchanger 34, which serves as the heating core within the airflow path. In both the first and second normal auxiliary heating modes, the output power of the heat transfer fluid heating device 32 is limited to at or below a preset power limit value. First normal auxiliary heating mode

[0077] In Fig. Figure 3 shows the flow of refrigerant and heat transfer fluid in the first normal auxiliary heating mode. The refrigerant flow due to the heating mode performed in the first normal auxiliary heating mode is identical to the refrigerant flow in refrigerant circuit 20 in the heating mode described above and is therefore not described here.

[0078] As in Fig. As shown in Figure 3, in the first normal auxiliary heating mode, the heat transfer fluid flows into the heat transfer fluid heating device 32 in the auxiliary heating section 30 when it is supplied by the circulation pump 31. The heat transfer fluid flowing into the heat transfer fluid heating device 32 is heated to a set temperature, then passes through the heat transfer fluid-refrigerant heat exchanger 27 and flows into the airflow path internal heat exchanger 34.

[0079] The heat transfer fluid flowing into the heat exchanger 34 within the airflow path undergoes heat exchange with the air flowing in the airflow path 11. The heat transfer fluid flowing out of the heat exchanger 34 within the airflow path is drawn in by the circulation pump 31.

[0080] In the first normal auxiliary heating mode, the air flowing in the airflow path 11 is additionally heated in the heat exchanger 34 inside the airflow path, and this air is heated even further in the heat drain 16. Second normal auxiliary heating mode

[0081] In Fig. Figure 4 shows the flow of refrigerant and heat transfer fluid in the second normal auxiliary heating mode. In heating mode during the second normal auxiliary heating mode, the refrigerant flows in the refrigerant circuit 20 after being discharged from the compressor 21, as shown in Figure 4. Fig. The refrigerant shown in section 4, entering the heat sink 16, undergoes a heat exchange with the air in the airflow path 11, which extracts heat from it and cools it, causing it to condense. When the refrigerant flowing from the heat sink 16 reaches the first expansion valve 23a, its pressure is reduced and it then flows into the external heat exchanger 22. The refrigerant flowing into the external heat exchanger 22 evaporates and absorbs heat from the air blown in by the external fan 22a.

[0082] The refrigerant flowing from the external heat exchanger 22 passes through the second electromagnetic valve 24b and the second check valve 25b into the accumulator 26, where the gas and liquid phases are separated, and is then drawn in by the compressor 21. The refrigerant thus circulates in the refrigerant circuit 20.

[0083] A portion of the refrigerant flowing from the heat sink 16 passes through the first electromagnetic valve 24a, bypasses the refrigerant flow path 20e, and reaches the third expansion valve 23c via the refrigerant flow path 20c. At the third expansion valve 23c, the refrigerant experiences a pressure reduction and then flows into the heat transfer fluid-refrigerant heat exchanger 27, evaporates, and absorbs heat from the heat transfer fluid. The refrigerant flowing from the heat transfer fluid-refrigerant heat exchanger 27 then flows into the accumulator 26, where the gas and liquid phases are separated, and is then drawn in by the compressor 21.

[0084] In the second normal auxiliary heating mode, the heat transfer fluid flows into the heat transfer fluid heating device 32 in the auxiliary heating section 30 when it is supplied by the circulation pump 31. The heat transfer fluid flowing into the heat transfer fluid heating device 32 is heated to a set temperature and flows into the heat transfer fluid-refrigerant heat exchanger 27.

[0085] The heat transfer fluid flowing into the heat transfer fluid-refrigerant heat exchanger 27 undergoes heat exchange with the refrigerant flowing in the heat transfer fluid-refrigerant heat exchanger 27 and then flows into the heat exchanger 34 located within the airflow path. The heat transfer fluid flowing into the heat exchanger 34 located within the airflow path undergoes heat exchange with the air flowing in the airflow path 11. The heat transfer fluid flowing out of the heat exchanger 34 located within the airflow path is drawn in by the circulation pump 31.

[0086] In the second normal auxiliary heating mode, as in the first auxiliary heating mode, the air flowing in the airflow path 11 is additionally heated in the heat exchanger 34 inside the airflow path, and this air is heated even further by flowing into the heat drain 16.

[0087] In order to prevent a reduction in the performance of the compressor 21 in the second normal auxiliary heating mode as the refrigerant temperature drops, the temperature of the refrigerant is increased by exchanging heat with the heat transfer fluid heated at the heat transfer fluid heating device 32 at the heat transfer fluid-refrigerant heat exchanger 27 before it is drawn in by the compressor 21. Low-temperature auxiliary heating mode

[0088] The low-temperature auxiliary heating mode is a mode that is activated when the outside air temperature drops to a low temperature, such as -10 °C to -15 °C, which is lower than the temperature for which the normal auxiliary heating mode is set. In this mode, in conjunction with the heating of the air flowing in the airflow path 11, the temperature of the refrigerant is increased by the refrigerant undergoing heat exchange with the heat transfer fluid heated at the heat transfer fluid heating device 32 at the heat transfer fluid-refrigerant heat exchanger 27 before it is drawn in by the compressor 21. In the low-temperature auxiliary heating mode, the heat transfer fluid circulates in the first heat transfer fluid circuit 30b without flowing through the airflow path internal heat exchanger 34, which serves as the heating core.In low-temperature auxiliary heating mode, as in normal auxiliary heating mode, the output power of the heat transfer fluid heating device 32 is limited so that it is at or below a preset power limit value.

[0089] In Fig. Figure 5 shows the flow rate of the refrigerant and heat transfer fluid in low-temperature auxiliary heating mode. The refrigerant flow rate in refrigerant circuit 20 is identical to the refrigerant flow rate in normal auxiliary heating mode during low-temperature auxiliary heating mode and is therefore not described here.

[0090] As in Fig. As shown in Figure 5, the heat transfer fluid in the auxiliary heating section 30 flows into the heat transfer fluid heating device 32 in low-temperature auxiliary heating mode when it is supplied by the circulation pump 31. The heat transfer fluid flowing into the heat transfer fluid heating device 32 is heated to a set temperature and flows into the heat transfer fluid-refrigerant heat exchanger 27.

[0091] The heat transfer fluid flowing into the heat transfer fluid-refrigerant heat exchanger 27 undergoes a heat exchange with the refrigerant flowing in the heat transfer fluid-refrigerant heat exchanger 27 and then flows into the temperature control target device 100. The heat transfer fluid flowing into the temperature control target device 100 performs a temperature regulation of the temperature control target device 100 and is then drawn in by the circulation pump 31.

[0092] If the outside air temperature is low, between -10 °C and -15 °C, and the heat exchange between the refrigerant and the outside air through the external heat exchanger 22 might be insufficient, it is possible in low-temperature auxiliary heating mode to regulate the temperature of the temperature of the refrigerant by increasing the temperature of the refrigerant through heat exchange between the heat transfer fluid heated by the heat transfer fluid heating device 32 and the refrigerant at the heat transfer fluid-refrigerant heat exchanger 27, thereby regulating the temperature of the temperature control target device 100 by means of heat exchange with the refrigerant.

[0093] By preventing the heat transfer fluid from flowing through the airflow path internal heat exchanger 34 in low-temperature auxiliary heating mode, the intake pressure at the compressor 21 increases further than in normal heating mode, making it possible to increase the output power of the compressor 21, thus reducing the output power of the heat transfer fluid heating device 32.

[0094] To prevent a reduction in the lifespan / performance of the battery forming the temperature control target device 100, the temperature of the heat transfer medium is also regulated in low-temperature auxiliary heating mode so that the operating temperature is, for example, in the range of 10 °C to 40 °C. Emergency heating mode

[0095] The emergency auxiliary heating mode is a mode that is activated in urgent cases when the outside air temperature drops extremely low below -15 °C and the refrigerant temperature falls too low, posing a risk of compressor 21 failure, or when compressor 21 is indeed defective, and the control device 40 determines that air conditioning operation using refrigerant circuit 20 is possible, but no air conditioning operation takes place, or air conditioning operation using refrigerant circuit 20 is not possible. In emergency auxiliary heating mode, operation according to the heating mode does not occur; instead, the air flowing in the airflow path 11 is heated only by means of the heat transfer fluid heated at the heat transfer fluid heating device 32. Therefore, this heat transfer fluid circulates in the second heat transfer fluid circuit 30c in such a way that it flows through the heat exchanger 34, which serves as the heating core of the airflow path.

[0096] Fig. Figure 6 shows the flow of the heat transfer fluid in emergency auxiliary heating mode. As in Fig. As shown in Figure 6, the heat transfer fluid in the auxiliary heating section 30 flows into the heat transfer fluid heating device 32 in emergency auxiliary heating mode when it is supplied by the circulation pump 31. The heat transfer fluid flowing into the heat transfer fluid heating device 32 is heated to a set temperature, then passes through the heat transfer fluid-refrigerant heat exchanger 27 and flows into the airflow path internal heat exchanger 34.

[0097] The heat transfer fluid flowing into the heat exchanger 34 within the airflow path undergoes heat exchange with the air flowing in the airflow path 11. The heat transfer fluid flowing out of the heat exchanger 34 within the airflow path is drawn in by the circulation pump 31.

[0098] Since heating operation according to the heating mode is not possible in emergency auxiliary heating mode, heat exchange takes place between the heat transfer medium and the air flowing in the airflow path 11 via the heat exchanger 34 located within the airflow path, and the air heated by this heat exchange is used for heating. The power limitation of the heat transfer medium heating device 32 is therefore only lifted in emergency auxiliary heating mode, allowing it to operate at maximum output power.

[0099] As described above, in the vehicle air conditioning system 1 according to the present embodiment, one of three broadly subdivided modes is set as the auxiliary heating mode. The control device 40 assesses whether air conditioning operation is possible using the refrigerant circuit 20, and if it assesses that air conditioning operation is possible using the refrigerant circuit 20, it sets the normal auxiliary heating mode or the low-temperature auxiliary heating mode according to the outside air temperature. If it assesses that air conditioning operation is possible using the refrigerant circuit 20, but no air conditioning operation takes place, or if air conditioning operation is not possible using the refrigerant circuit 20, it sets the emergency auxiliary heating mode, in which the power limitation of the heat transfer fluid heating device 32 is lifted.

[0100] When the heating mode is set in the vehicle air conditioning system 1, it can be assessed, based on the condition of the compressor 21 and the outside air temperature, whether air conditioning operation using the refrigerant circuit 20 is possible, and the appropriate auxiliary heating mode can be set, and the environment in the passenger compartment can be kept comfortable, while a reduction in the service life of the heat transfer fluid heating device 32 is prevented as far as possible. Processing operations

[0101] Next, with reference to Fig. 7 describes the processing operations of the vehicle air conditioning system 1 according to the present embodiment when the heating mode is executed.

[0102] The steps for the processes described below are given in an exemplary sequence, but there is no restriction to the specified sequence. As long as no conflicts arise regarding the processing result, the sequence of the flowchart can therefore be used. Fig. 7 will be changed.

[0103] When the heating mode is executed as air conditioning mode (ST1), the control device 40 assesses, as in Fig. 7 shown, in its function as an auxiliary heating operation performance evaluation section, whether it is necessary to switch to the auxiliary heating mode as the operating mode (ST2).

[0104] If the control device 40 in ST2 judges that it is necessary to switch to the auxiliary heating mode as the operating mode (ST2: Yes), it next assesses, in its function as the air conditioning operation execution assessment section, whether the air conditioning operation is possible using the refrigerant circuit 20 (i.e., whether the air conditioning operation should be carried out) (ST3).

[0105] If, on the other hand, the control device 40 decides in ST2 that it is not necessary to switch to the auxiliary heating mode as the operating mode (ST2: No), it controls the operation of the individual components in its function as an operating control section in such a way that the operation continues according to the set heating mode (ST4), and the processing ends.

[0106] If the control device 40 in ST3 judges that air conditioning operation is possible using the refrigerant circuit 20 (ST3: Yes), it next assesses, in its function as an outside air temperature assessment section, whether the outside air temperature is at or below the preset mode selection temperature threshold (ST5).

[0107] If, on the other hand, the control device 40 judges in ST3 that air conditioning operation using the refrigerant circuit 20 is not possible or does not take place (ST3: No), it controls the operation of the individual components in its function as an operating control section in such a way that the processing is carried out in accordance with the emergency auxiliary heating mode (ST6), and the processing ends.

[0108] If the control device 40 in ST5 judges that the outside air temperature is at or below the mode selection temperature threshold (ST5: Yes), in its function as an operating control section, it controls the operation of the individual components in such a way that the processing is carried out in accordance with the low temperature auxiliary heating mode (ST7), and the processing ends.

[0109] If, on the other hand, the control device 40 judges in ST5 that the outside air temperature is above the mode selection temperature threshold (ST5: No), it controls the operation of the individual components in its function as an operating control section in such a way that the processing is carried out according to the normal auxiliary heating mode (ST8), and the processing ends. Mode of action

[0110] As described above, the vehicle air conditioning system 1 according to the present embodiment includes the airflow path 11, in which air supplied to the passenger compartment flows, the refrigerant circuit 20 with the compressor 21, which compresses the refrigerant, the heat sink 16, which causes the refrigerant to release heat, the heat sink 15, which causes the refrigerant to absorb heat, and the external heat exchanger 22, which is provided outside the passenger compartment and causes the refrigerant to release or absorb heat, the auxiliary heating section 30, which includes the heat transfer fluid heating device 32, which heats the heat transfer fluid, and the airflow path internal heat exchanger 34, which is provided on the airflow path 11 and causes the heat transfer fluid to release heat, and in which the heat transfer fluid heated at the heat transfer fluid heating device 32 circulates, and the heat transfer fluid-refrigerant heat exchanger 27.which is connected in parallel with the heat sink 15, causes the refrigerant flowing from the first refrigerant flow path (refrigerant flow path 20c) formed between the external heat exchanger 22 and the heat sink 15 to experience a pressure reduction at the third expansion valve 23c, and causes the refrigerant, which has experienced a pressure reduction through the third expansion valve 23c, to absorb heat and thus perform a heat exchange with the heat transfer fluid, and the control device 40, which, when it judges that air conditioning operation is possible using the refrigerant circuit 20 and the addition of the auxiliary heating function is necessary, operates the heat transfer fluid heating device 32 based on a power limit value that is set to 50% or less of the maximum output power of the heat transfer fluid heating device 32.

[0111] When the heating mode is set, the appropriate auxiliary heating mode can therefore be selected based on the operating state of the compressor 21 and the outside air temperature, and the environment in the passenger compartment can be kept comfortable. Since the power output of the heat transfer fluid heating device 32 is operated at or below a power limit value that is set such that its service life is not reduced, the environment in the passenger compartment can be kept comfortable, while a reduction in the service life of the heat transfer fluid heating device 32 is prevented as far as possible.

[0112] In the vehicle air conditioning system 1 according to the present embodiment, the refrigerant circuit 20 comprises the third refrigerant flow path (refrigerant flow path 20e) branching off from the second refrigerant flow path (refrigerant flow path 20b) formed between the heat sink 16 and the external heat exchanger 22, which is connected to the first refrigerant flow path bypassing the external heat exchanger 22; the auxiliary heating section 30 comprises the first heat transfer fluid circuit 30b, which allows the heat transfer fluid heated at the heat transfer fluid heating device 32 to flow back into the heat transfer fluid heating device 32 via the heat transfer fluid-refrigerant heat exchanger 27; and the second heat transfer fluid circuit 30c, which allows the heat transfer fluid heated at the heat transfer fluid heating device 32 to flow into the heat transfer fluid-refrigerant heat exchanger 27.The control device 40 allows the heat transfer fluid flowing from the heat transfer fluid-refrigerant heat exchanger 27 to flow into the heat exchanger 34 located within the airflow path, and allows the heat transfer fluid flowing from the heat exchanger 34 located within the airflow path to flow again into the heat transfer fluid heating device 32, wherein the control device 40, when the outside air temperature is at or below a preset mode selection temperature threshold, effects a heat exchange at the heat transfer fluid-refrigerant heat exchanger 27 between the heat transfer fluid circulating in the first heat transfer fluid circuit 30b and the refrigerant flowing into the heat transfer fluid-refrigerant heat exchanger 27 through the third refrigerant flow path.

[0113] The heat transfer fluid circulates in the first heat transfer circuit 30b without flowing through the heat exchanger 34 located within the airflow path, and the refrigerant circulating in the refrigerant circuit 20 undergoes heat exchange with the heat transfer fluid flowing in the first heat transfer circuit 30b at the heat transfer-refrigerant heat exchanger 27. Therefore, operation in heating mode is possible with increased output power from the compressor 21. Even at low outside air temperatures of, for example, -10 °C or below, the interior of the passenger compartment can thus be kept comfortable.

[0114] In the vehicle air conditioning system 1 according to the present embodiment, the control device 40 also removes the power limitation of the heat transfer fluid heating device 32 by the power limitation value in the event that it judges that air conditioning operation using the refrigerant circuit 20 is possible, but no air conditioning operation takes place, or judges that no air conditioning operation using the refrigerant circuit 20 is possible, and causes the heat transfer fluid to be heated, and allows the heat transfer fluid to circulate in the second heat transfer fluid circuit 30c and to heat the air flowing in the airflow path 11.

[0115] Only in emergencies, for example in the case of an extremely low outside air temperature of below -15 °C or if the compressor 21 is actually defective, and air conditioning operation using the refrigerant circuit 20 is possible, but no air conditioning operation takes place, or air conditioning operation using the refrigerant circuit 20 is not possible, is the power limitation of the heat transfer fluid heating device 32 lifted and the heating function thus achieved, which is why the environment in the passenger compartment can be kept comfortable, while a reduction in the service life of the heat transfer fluid heating device 32 is prevented as far as possible. LIST OF REFERENCE MARKS 1 Vehicle air conditioning 10 air conditioning units 11 Airflow path (11a Bypass airflow path) 12 Intake opening (12a Outside air intake opening, 12b Inside air intake opening) 13 Intake opening switching flap 14 internal fans 15 Heat sinks 16 heat sinks 17 Air mixing flap 20 Refrigerant circuit (20a-20g refrigerant flow path) 21 Compressor 22 external heat exchangers 23 Expansion valve (23a: first expansion valve, 23b: second expansion valve, 23c: third expansion valve) 24 electromagnetic valve (24a: first electromagnetic valve, 24b: second electromagnetic valve) 25 Check valve (25a: first check valve, 25b: second check valve) 26 Accumulator 27 Heat transfer fluid-refrigerant heat exchangers 28 Control valve 30 Auxiliary heating section (30a: heat transfer fluid circuit, 30b: first heat transfer fluid circuit, 30c: second heat transfer fluid circuit) 31 Circulation pump 32 Heat transfer fluid heating device 33 Directional changeover valve 34 airflow path internal heat exchanger 40 Control device

Claims

[1] Vehicle air conditioning system (1), comprising: an airflow path (11) in which air supplied to a passenger compartment flows, a refrigerant circuit (20) with a compressor (21) that compresses the refrigerant, a heat sink (16) that causes the refrigerant to release heat, and a heat sink (15) that causes the refrigerant to absorb heat. and an external heat exchanger (22) which is provided outside the passenger compartment and causes the refrigerant to release or absorb heat, an auxiliary heating section (30) comprising a heat transfer fluid heating device (32) which heats a heat transfer fluid, and includes an airflow path internal heat exchanger (34) which is provided on the airflow path (11) and causes the heat transfer medium to release heat, and in which the heat transfer medium heated at the heat transfer medium heating device (32) circulates, a heat transfer fluid-refrigerant heat exchanger (27) which causes the refrigerant flowing from a first refrigerant flow path (20c) formed between the external heat exchanger (22) and the heat sink (15) to absorb heat and thus carry out a heat exchange with the heat transfer fluid, an air conditioning operation performance evaluation section designed to assess whether air conditioning operation is possible using the refrigerant circuit (20), an auxiliary heating operation performance evaluation section, which is set up to assess whether an auxiliary heating function is added, an operating control section which is configured, when the air conditioning operation performance evaluation section determines that air conditioning operation using the refrigerant circuit (20) is possible, and the auxiliary heating operation performance evaluation section determines that adding the auxiliary heating function is necessary, to operate the heat transfer fluid heating device (32) while limiting its output power to or below a specified power limit value, and an outdoor air temperature assessment section designed to assess whether the outdoor air temperature is at or below a pre-set temperature threshold, wherein the refrigerant circuit (20) comprises a third refrigerant flow path (20e) which branches off from a second refrigerant flow path (20b) formed between the heat sink (16) and the external heat exchanger (22) and is connected to the first refrigerant flow path (20c) bypassing the external heat exchanger (22), wherein the auxiliary heating section (30) includes a first heat transfer fluid circuit (30b), which allows the heat transfer fluid heated at the heat transfer fluid heating device (32) to flow back into the heat transfer fluid heating device (32) via the heat transfer fluid-refrigerant heat exchanger (27), and comprises a second heat transfer fluid circuit (30c) which allows the heat transfer fluid heated at the heat transfer fluid heating device (32) to flow into the heat transfer fluid-refrigerant heat exchanger (27), allows the heat transfer fluid flowing out of the heat transfer fluid-refrigerant heat exchanger (27) to flow into the heat exchanger (34) within the airflow path, and allows the heat transfer fluid flowing out of the heat exchanger (34) within the airflow path to flow back into the heat transfer fluid heating device (32), wherein the operating control section is designed to circulate the heat transfer fluid in the first heat transfer fluid circuit (30b) and to effect a heat exchange at the heat transfer fluid-refrigerant heat exchanger (27) between the heat transfer fluid circulating in the first heat transfer fluid circuit (30b) and the refrigerant flowing into the heat transfer fluid-refrigerant heat exchanger (27) through the third refrigerant flow path (20e). [2] Vehicle air conditioning system (1) according to claim 1, wherein the power limiting value is set to 50% or less of the maximum output power of the heat transfer fluid heating device (32). [3] Vehicle air conditioning system (1) according to claim 1 or 2, wherein the operating control section, in the event that the air conditioning operation performance evaluation section determines that air conditioning operation using the refrigerant circuit (20) is possible but no air conditioning operation takes place, or determines that no air conditioning operation using the refrigerant circuit (20) is possible, removes the power limitation of the heat transfer fluid heating device (32) by the power limitation value and causes the heat transfer fluid to be heated, and allows the heat transfer fluid to circulate in the second heat transfer fluid circuit (30c) and to heat the air flowing in the airflow path (11).

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