Vehicular air conditioner and method for controlling same

Abstract

The present invention provides a vehicular air conditioner that can suppress uneven liquid distribution of a heat medium inside a cooler core and a heater core or suppress a distribution of air temperatures occurring as a result of a heat medium temperature difference arising between the upstream and downstream sides when performing dehumidifying heating or dehumidifying cooling. The flow rates of a chilled water pump (32) and a hot water pump (22) and the valve positions of a cooler core–side flow control valve (30), a heater core–side flow control valve (20), and an external heat exchange–side flow control valve (40) are controlled such that the flow rates of chilled water through a cooler core (28) and hot water through a heater core (18) are each at a target value without falling below a prescribed value.

Description

Vehicle air conditioning system and control method thereof

[0001] The present disclosure relates to a vehicle air conditioning system and a control method thereof.

[0002] Patent Document 1 discloses a vehicle air conditioner that generates hot and cold water using a refrigeration cycle to condition the vehicle. The vehicle air conditioner absorbs heat from outside air to perform dehumidifying and heating in an outside air heat pump dehumidifying and heating mode (see FIG. 10 of the document). The document also discloses that a cold water flow rate that can transfer the required amount of heat is calculated and the discharge flow rate of the cold water pump is controlled (see paragraph

[0201] of the document).

[0003] Patent No. 6197657

[0004] The above-mentioned document only discloses that the flow rate of chilled water is based on the required heat amount, but does not disclose the minimum flow rate of chilled water to be flowed through the cooler core. Furthermore, the document also suggests that the flow rate of chilled water to the cooler core is reduced or flowed intermittently to avoid frost (paragraph

[0202] of the document).

[0005] However, if the flow rate of the cooler core falls below a predetermined value, the distribution of the cold water inside the heater core becomes uneven, or a temperature difference occurs between the upstream and downstream sides of the cold water, causing a distribution of the air temperature. These problems also occur with the hot water flowing through the heater core.

[0006] The present disclosure has been made in consideration of the above circumstances, and aims to provide a vehicle air conditioning system and a control method thereof that can prevent uneven distribution of heat transfer medium liquid inside the cooler core and heater core when performing dehumidifying heating or dehumidifying cooling, or prevent a temperature difference in the heat transfer medium between the upstream and downstream sides, causing a distribution in air temperature.

[0007] A vehicle air conditioning system according to one aspect of the present disclosure includes a refrigeration cycle having a compressor that compresses a refrigerant, a condenser that condenses the refrigerant compressed by the compressor, an expansion valve that expands the refrigerant condensed by the condenser, and an evaporator that evaporates the refrigerant expanded by the expansion valve; a cooler core that cools air to be introduced into a vehicle compartment; a heater core that heats the air to be introduced into the vehicle compartment; a cooler core side heat medium circulation flow path that circulates a heat medium between the cooler core and the evaporator; a heater core side heat medium circulation flow path that circulates the heat medium between the heater core and the condenser; an external heat exchanger that exchanges heat between the heat medium guided from the cooler core side heat medium circulation flow path or the heater core side heat medium circulation flow path and outside air; a cooler core side pump provided in the cooler core side heat medium circulation flow path that circulates the heat medium; a heater core side pump that is connected to the compressor and circulates the heat medium; a cooler core side flow regulation valve that adjusts the flow rate of the heat medium flowing through the cooler core; a heater core side flow regulation valve that adjusts the flow rate of the heat medium flowing through the heater core; an external heat exchanger side flow regulation valve that adjusts the flow rate of the heat medium flowing through the external heat exchanger; and a control unit that controls the compressor, the cooler core side pump, the heater core side pump, the cooler core side flow regulation valve, the heater core side flow regulation valve, and the external heat exchanger side flow regulation valve to perform dehumidifying heating or dehumidifying cooling, and the control unit controls the flow rates of the cooler core side pump and the heater core side pump, as well as the openings of the cooler core side flow regulation valve, the heater core side flow regulation valve, and the external heat exchanger side flow regulation valve so that the flow rates of the heat medium flowing through the cooler core and the heat medium flowing through the heater core do not fall below a predetermined value and reach a target value.

[0008] A method for controlling a vehicle air conditioning system according to one aspect of the present disclosure includes a refrigeration cycle including a compressor that compresses a refrigerant, a condenser that condenses the refrigerant compressed by the compressor, an expansion valve that expands the refrigerant condensed by the condenser, and an evaporator that evaporates the refrigerant expanded by the expansion valve, a cooler core that cools air to be introduced into a vehicle compartment, a heater core that heats the air to be introduced into the vehicle compartment, a cooler-core-side heat medium circulation flow path that circulates a heat medium between the cooler core and the evaporator, a heater-core-side heat medium circulation flow path that circulates a heat medium between the heater core and the condenser, an external heat exchanger that exchanges heat between the heat medium guided from the cooler-core-side heat medium circulation flow path or the heater-core-side heat medium circulation flow path and outside air, and a control valve that controls the control valve to control the control valve to control the control valve. a cooler core side pump provided in the heater core side heat medium circulation flow path for circulating the heat medium; a cooler core side flow control valve for adjusting the flow rate of the heat medium flowing through the cooler core; a heater core side flow control valve for adjusting the flow rate of the heat medium flowing through the heater core; and an external heat exchanger side flow control valve for adjusting the flow rate of the heat medium flowing through the external heat exchanger, wherein the flow rates of the cooler core side pump and the heater core side pump, as well as the openings of the cooler core side flow control valve, the heater core side flow control valve, and the external heat exchanger side flow control valve are controlled so that the flow rates of the heat medium flowing through the cooler core and the heat medium flowing through the heater core do not fall below predetermined values ​​and reach target values.

[0009] When performing dehumidifying heating or dehumidifying cooling, it is possible to prevent the liquid distribution of the heat transfer medium from becoming uneven inside the cooler core and heater core, or the temperature difference of the heat transfer medium from occurring between the upstream and downstream sides, causing a distribution in the air temperature.

[0010] 1 is a schematic configuration diagram of a vehicle air conditioner according to a first embodiment of the present disclosure. FIG. 1 is a schematic configuration diagram showing an operating mode in which chilled water temperature control by a compressor of the vehicle air conditioner of FIG. 1 [when the outside air temperature is low (high thermal load)] is performed. FIG. 1 is a schematic configuration diagram showing an operating mode in which chilled water temperature control by a compressor of the vehicle air conditioner of FIG. 1 [when the outside air temperature is low (low thermal load)] is performed. FIG. 1 is a schematic configuration diagram showing an operating mode in which chilled water temperature control by a compressor of the vehicle air conditioner of FIG. 1 [when the outside air temperature is high (low thermal load)] is performed. FIG. 1 is a schematic configuration diagram showing an operating mode in which hot water temperature control by a compressor of the vehicle air conditioner of FIG. 1 [when the outside air temperature is low (high thermal load)] is performed. 1 is a schematic configuration diagram showing an operation mode of hot water temperature control by the compressor of the vehicle air conditioner of FIG. 1 [when the outside air temperature is high (small thermal load)]. FIG. 1 is a schematic configuration diagram showing an operation mode of hot water temperature control by the compressor of the vehicle air conditioner of FIG. 1 [when the outside air temperature is high (large thermal load)]. FIG. 1 is a flowchart showing a control flow of a compressor according to a first embodiment of the present disclosure. FIG. 1 is a flowchart showing a control flow of a hot water pump according to a first embodiment of the present disclosure. FIG. 1 is a flowchart showing a control flow of a chilled water pump according to a first embodiment of the present disclosure. FIG. 1 is a flowchart showing a control flow of each flow regulation valve according to a first embodiment of the present disclosure. FIG. 13A is a flowchart showing a continuation of the control flow of FIG. 13A. FIG. 13B is a schematic configuration diagram of a vehicle air conditioner according to a second embodiment of the present disclosure, showing a schematic configuration diagram showing an operation mode of high-load dehumidifying heating operation [when the outside air temperature is even lower (largest thermal load)]. FIG. 13C is a schematic configuration diagram showing an operation mode of defrosting and dehumidifying operation [when the external heat exchanger is determined to be frosted] according to a second embodiment of the present disclosure. 1 is a schematic diagram showing an operation mode of a frost-avoidance dehumidifying operation [during continuous operation after defrosting of an external heat exchanger] according to a second embodiment of the present disclosure. 2 is a schematic diagram showing an operation mode of a high-load dehumidifying and cooling operation [when the outdoor air temperature is even higher (maximum heat load)] according to a second embodiment of the present disclosure. 3 is a flowchart showing a control flow according to a second embodiment of the present disclosure.18B is a flowchart showing a control flow following that of FIG. 18A.

[0011] Hereinafter, embodiments according to the present disclosure will be described with reference to the drawings. [First Embodiment] Hereinafter, a first embodiment according to the present disclosure will be described with reference to Fig. 1. Fig. 1 shows an outline of a vehicle air conditioner 1 according to this embodiment. The vehicle air conditioner 1 includes a refrigeration cycle 3, a heater core side heat medium circulation flow path 5, and a cooler core side heat medium circulation flow path 7.

[0012] The refrigeration cycle 3 includes a compressor 10 that compresses a refrigerant, a condenser 11 that condenses the refrigerant compressed by the compressor 10, an expansion valve 12 that expands the refrigerant condensed by the condenser 11, an evaporator 13 that evaporates the refrigerant expanded by the expansion valve 12, and an accumulator 14 that separates the refrigerant guided from the evaporator 13 into gas and liquid. The compressor 10 may be, for example, a scroll compressor or a rotary compressor. The operation of the refrigeration cycle 3 is controlled by a control unit (not shown).

[0013] The heater core side heat transfer medium circulation flow path 5 is a flow path that mainly supplies hot water (heat transfer medium, coolant) heated in the condenser 11 to the heater core 18 and returns the hot water flowing out from the heater core 18 to the condenser 11.

[0014] A heater core side upstream three-way valve 20a is provided upstream of the heater core 18 (upper side in FIG. 1 ), and a heater core side downstream three-way valve 20b is provided downstream of the heater core 18 (lower side in FIG. 1 ). The opening degree of the heater core side upstream three-way valve 20a is controlled by a control unit (not shown), allowing hot water from the heater core side heat medium circulation channel 5 and cold water from the cooler core side heat medium circulation channel 7 to flow to the heater core 18. The heater core side downstream three-way valve 20b is controlled by a control unit (not shown), allowing hot water flowing out from the heater core 18 to flow to the heater core side heat medium circulation channel 5 and the cooler core side heat medium circulation channel 7. The opening degrees of the heater core side upstream three-way valve 20a and the heater core side downstream three-way valve 20b (hereinafter collectively referred to as the "heater core side flow adjustment valve 20") are controlled synchronously by a single actuator. The present disclosure is not limited to the above-described three-way valve, and other three-way valves or two-way valves may be combined.

[0015] A hot water pump (heater core side pump) 22 is provided downstream of the condenser 11 in the heater core side heat medium circulation flow path 5. The rotation speed, i.e., the flow rate, of the hot water pump 22 is controlled by a control unit (not shown). A hot water temperature sensor 24 is provided downstream of the hot water pump 22. The measurement value of the hot water temperature sensor 24 is sent to the control unit (not shown).

[0016] The cooler core side heat medium circulation passage 7 is a passage that mainly supplies cold water (heat medium, coolant) cooled in the evaporator 13 to the cooler core 28 and returns the cold water flowing out from the cooler core 28 to the evaporator 13.

[0017] A cooler core side upstream three-way valve 30a is provided upstream of the cooler core 28 (upper side in FIG. 1 ), and a cooler core side downstream three-way valve 30b is provided downstream of the cooler core 28 (lower side in FIG. 1 ). The opening degree of the cooler core side upstream three-way valve 30a is controlled by a control unit (not shown), allowing cold water from the cooler core side heat medium circulation channel 7 and hot water from the heater core side heat medium circulation channel 5 to flow to the cooler core 28. The cooler core side downstream three-way valve 30b is controlled by a control unit (not shown), allowing cold water flowing out from the cooler core 28 to flow to the cooler core side heat medium circulation channel 7 and the heater core side heat medium circulation channel 5. The opening degrees of the cooler core side upstream three-way valve 30a and the cooler core side downstream three-way valve 30b (hereinafter collectively referred to as the "cooler core side flow adjustment valve 30") are controlled synchronously by a single actuator. The present disclosure is not limited to the above-described three-way valve, and other three-way valves or two-way valves may be combined.

[0018] A chilled water pump (cooler core side pump) 32 is provided in the cooler core side heat medium circulation passage 7 downstream of the evaporator 13. The rotation speed, i.e., the flow rate, of the chilled water pump 32 is controlled by a control unit (not shown). A chilled water temperature sensor 34 is provided downstream of the chilled water pump 32. The measurement value of the chilled water temperature sensor 34 is sent to the control unit (not shown).

[0019] The heater core 18 and the cooler core 28 are used as a heating, ventilation, and air conditioning (HVAC) system (not shown). As shown by the white arrow in Fig. 1 , air cooled by the cooler core 28 is heated by the heater core 18 and guided into the vehicle cabin along an air flow A1. A warm air temperature sensor 36 is provided downstream of the air flow A1 from the heater core 18, and a cold air temperature sensor 37 is provided downstream of the air flow A1 from the cooler core 28. Measurement values ​​from the air temperature sensors 36 and 37 are sent to a control unit (not shown).

[0020] An external heat exchanger 38 is connected to the heater core side heat medium circulation passage 5 and the cooler core side heat medium circulation passage 7. The external heat exchanger 38 exchanges heat between hot water or cold water and outside air.

[0021] An external heat exchanger-side upstream three-way valve 40a is provided upstream of the external heat exchanger 38 (upper side in FIG. 1 ), and an external heat exchanger-side downstream three-way valve 40b is provided downstream of the external heat exchanger 38 (lower side in FIG. 1 ). The opening of the external heat exchanger-side upstream three-way valve 40a is controlled by a control unit (not shown), allowing cold water from the cooler core-side heat medium circulation channel 7 and hot water from the heater core-side heat medium circulation channel 5 to flow to the external heat exchanger 38. The external heat exchanger-side downstream three-way valve 40b is controlled by a control unit (not shown), allowing hot water or cold water flowing out of the external heat exchanger 38 to flow to the cooler core-side heat medium circulation channel 7 and the heater core-side heat medium circulation channel 5. The openings of the external heat exchanger-side upstream three-way valve 40a and the external heat exchanger-side downstream three-way valve 40b (hereinafter collectively referred to as the "external heat exchanger-side flow adjustment valves 40") are controlled synchronously by a single actuator. The present disclosure is not limited to the above-described three-way valve, and other three-way valves or two-way valves may be combined.

[0022] A bypass flow path 42 is provided between the upstream side of the hot water pump 22 and the upstream side of the cold water pump 32. The bypass flow path 42 allows hot water to flow from the heater core side heat medium circulation flow path 5 to the cooler core side heat medium circulation flow path 7, or allows cold water to flow from the cooler core side heat medium circulation flow path 7 to the heater core side heat medium circulation flow path 5. A reserve tank 44 that stores hot water or cold water (coolant) is provided in the bypass flow path 42.

[0023] The control unit is composed of, for example, a CPU (Central Processing Unit), RAM (Random Access Memory), ROM (Read Only Memory), and a computer-readable storage medium. A series of processes for realizing various functions is stored in a storage medium, for example, in the form of a program. The CPU reads this program into RAM and executes information processing and arithmetic operations to realize various functions. The program may be pre-installed in a ROM or other storage medium, provided in a state stored in a computer-readable storage medium, or distributed via wired or wireless communication means. Examples of computer-readable storage media include magnetic disks, magneto-optical disks, CD-ROMs, DVD-ROMs, and semiconductor memories.

[0024] Next, the operation of each operation mode using the vehicle air conditioner 1 having the above configuration will be described.

[0025] <Chilled Water Temperature Control by Compressor 10 [When the Outside Air Temperature is Low (High Heat Load)]> Figure 2 shows an operation mode of chilled water temperature control by compressor 10 [When the Outside Air Temperature is Low (High Heat Load)]. In this mode, chilled water temperature control is performed by compressor 10, controlling the rotation speed of compressor 10 so that the chilled water temperature measured by chilled water temperature sensor 34 reaches a target value. This is an operation mode when the outside air temperature is low and the heat load is high, such as in winter.

[0026] In the figure, the flow path through which hot water flows is indicated by a thick solid line, and the flow path through which cold water flows is indicated by a thick dashed line. In addition, the compressor, flow control valve, pump, etc. controlled by the control unit are indicated by dashed lines. These notations are the same in the following figures.

[0027] The vehicle air conditioner 1 shown in the figure performs dehumidifying and heating by operating a heat pump that absorbs heat from outside air.

[0028] The rotation speed of the compressor 10 is controlled by the control unit so that the chilled water temperature measured by the chilled water temperature sensor 34 becomes a target value.

[0029] The rotation speed of the chilled water pump 32 is controlled by the control unit so that the cooler core outlet air temperature measured by the chilled air temperature sensor 37 becomes a target value. The rotation speed of the chilled water pump 32 is also controlled so that the chilled water flow rate flowing through the cooler core 28 does not fall below a predetermined value. This predetermined value refers to the chilled water flow rate at which the chilled water liquid distribution inside the cooler core 28 becomes uneven or a temperature difference between the upstream and downstream sides of the heat medium occurs, causing a distribution in the air temperature.

[0030] The rotation speed of the hot water pump 22 is controlled by the control unit so that the heater core outlet air temperature measured by the hot air temperature sensor 36 becomes a target value. The rotation speed of the hot water pump 22 is also controlled so that the flow rate of hot water flowing through the heater core 18 does not fall below a predetermined value.

[0031] The heater core side flow adjustment valve 20 is fully opened by the control unit, thereby performing heating corresponding to a large heat load.

[0032] The external heat exchanger side flow regulation valve 40 is selected by the control unit to allow cold water to flow and is fully open, thereby absorbing a large amount of heat from the outside air to cope with a large heat load.

[0033] The cooler core side flow adjustment valve 30 is controlled by the control unit so that the hot water temperature measured by the hot water temperature sensor 24 becomes a target value. In this way, by throttling the cooler core side flow adjustment valve 30 and increasing the flow rate of cold water to the external heat exchanger 38, the amount of heat absorbed from the outside air is increased, and control is performed to maintain the hot water temperature.

[0034] This operation mode is shown in the table below.

[0035] <Chilled Water Temperature Control by Compressor 10 [When the Outside Air Temperature is Low (Low Heat Load)]> Fig. 3 shows an operation mode of chilled water temperature control by compressor 10 [When the Outside Air Temperature is Low (Low Heat Load)]. This operation mode is for a case where the heat load is smaller than that of the operation mode shown in Fig. 2.

[0036] The vehicle air conditioner 1 shown in the figure performs dehumidifying and heating by operating a heat pump that absorbs heat from outside air. The difference from the operating mode in Figure 2 is that the external heat exchanger-side flow regulation valve 40 is opened from fully open to an intermediate position, and the cooler-core-side flow regulation valve 30 is fully opened. The external heat exchanger-side flow regulation valve 40 is controlled by the control unit so that the hot water temperature measured by the hot water temperature sensor 24 reaches a target value. In this way, the hot water temperature can be maintained by throttling the external heat exchanger-side flow regulation valve 40 and suppressing the amount of heat absorption. Since the cooler-core-side flow regulation valve 30 is fully open, a sufficient flow rate of cold water flowing through the cooler core 28 is ensured.

[0037] This operation mode is shown in the table below.

[0038] <Chilled Water Temperature Control by Compressor 10 [When the Outside Air Temperature is High (Low Heat Load)]> Figure 4 shows an operation mode of chilled water temperature control by the compressor 10 [When the Outside Air Temperature is High (Low Heat Load)]. In this mode, as in Figures 2 and 3, chilled water temperature control is performed by the compressor 10, controlling the rotation speed of the compressor 10 so that the chilled water temperature measured by the chilled water temperature sensor 34 reaches a target value. This is an operation mode when the outside air temperature is high and the heat load is low, such as in summer.

[0039] The vehicle air conditioner 1 shown in the figure performs dehumidifying and cooling by cooling operation in which heat is released to the outside air.

[0040] The rotation speed of the compressor 10 is controlled by the control unit so that the chilled water temperature measured by the chilled water temperature sensor 34 becomes a target value.

[0041] The rotation speed of the chilled water pump 32 is controlled by the control unit so that the cooler core outlet air temperature measured by the chilled air temperature sensor 37 becomes a target value. The cooler core side flow adjustment valve 30 is fully opened by the control unit. In addition, the rotation speed of the chilled water pump 32 is controlled so that the flow rate of chilled water flowing through the cooler core 28 does not fall below a predetermined value.

[0042] The rotation speed of the hot water pump 22 is controlled by the control unit so that the heater core outlet air temperature measured by the hot air temperature sensor 36 becomes a target value. The rotation speed of the hot water pump 22 is also controlled so that the flow rate of hot water flowing through the heater core 18 does not fall below a predetermined value.

[0043] The heater core side flow adjustment valve 20 is fully opened by the control unit.

[0044] The external heat exchanger side flow regulation valve 40 is selected by the control unit to allow hot water to flow, and is controlled so that the hot water temperature measured by the hot water temperature sensor 24 becomes the target value. In this way, by throttling the external heat exchanger side flow regulation valve 40 and allowing a small amount of hot water to flow, heat is released to the outside air and the hot water temperature is maintained.

[0045] This operation mode is shown in the table below.

[0046] <Chilled Water Temperature Control by Compressor 10 [When the Outside Air Temperature is High (Heavy Heat Load)]> Fig. 5 shows an operation mode of chilled water temperature control by compressor 10 [When the Outside Air Temperature is High (Heavy Heat Load)]. This operation mode is for a case where the heat load is greater than that of the operation mode shown in Fig. 4.

[0047] The vehicle air conditioner 1 shown in the figure performs dehumidifying and cooling by cooling operation that dissipates heat to outside air. The difference from the operating mode in Figure 4 is that the external heat exchanger side flow control valve 40 is changed from an intermediate opening to a fully open position, and the heater core side flow control valve 20 is changed from fully open to an intermediate opening position. The heater core side flow control valve 20 is controlled by the control unit so that the hot water temperature measured by the hot water temperature sensor 24 reaches a target value. In this way, by throttling the heater core side flow control valve 20 and increasing the hot water flow rate to the external heat exchanger 38, the amount of heat dissipated to the outside air is increased, and the hot water temperature is maintained.

[0048] This operation mode is shown in the table below.

[0049] <Hot Water Temperature Control by Compressor 10 [When the Outside Air Temperature is Low (High Heat Load)]> Figure 6 shows an operation mode of hot water temperature control by the compressor 10 [When the Outside Air Temperature is Low (High Heat Load)]. In this mode, hot water temperature control is performed by the compressor 10, controlling the rotation speed of the compressor 10 so that the hot water temperature measured by the hot water temperature sensor 24 reaches a target value. This is an operation mode when the outside air temperature is low and the heat load is high, such as in winter.

[0050] This operation mode differs from the operation mode shown in FIG. 2 in that the hot water temperature is controlled by the compressor 10 and the cold water temperature is controlled by the cooler core side flow adjustment valve 30, but the rest is the same.

[0051] This operation mode is shown in the table below.

[0052] <Hot water temperature control by compressor 10 [when outside air temperature is low (low thermal load)]> Figure 7 shows an operation mode for chilled water temperature control by compressor 10 [when outside air temperature is low (low thermal load)]. This operation mode is for a case where the thermal load is smaller than that of the operation mode shown in Figure 6. This operation mode is similar to the operation mode shown in Figure 3, but differs in that the compressor 10 is used for hot water temperature control.

[0053] The vehicle air conditioner 1 shown in the figure performs dehumidifying and heating by operating a heat pump that absorbs heat from outside air. The difference from the operating mode in Figure 6 is that the external heat exchanger-side flow regulation valve 40 is changed from fully open to an intermediate opening, and the cooler core-side flow regulation valve 30 is fully open. The external heat exchanger-side flow regulation valve 40 is controlled by the control unit so that the chilled water temperature measured by the chilled water temperature sensor 34 reaches a target value. In this way, the chilled water temperature can be maintained by throttling the external heat exchanger-side flow regulation valve 40 and reducing the amount of heat absorption.

[0054] This operation mode is shown in the table below.

[0055] <Hot Water Temperature Control by Compressor 10 [When the Outside Air Temperature is High (Low Thermal Load)]> Figure 8 shows an operation mode for hot water temperature control by the compressor 10 [When the outside air temperature is high (low thermal load)]. In this mode, similar to Figures 6 and 7, hot water temperature control is performed by the compressor 10, controlling the rotation speed of the compressor 10 so that the hot water temperature measured by the hot water temperature sensor 24 reaches a target value. This is an operation mode when the outside air temperature is high and the thermal load is low, such as in summer. Note that this operation mode is similar to the operation mode shown in Figure 4, but differs in that the compressor 10 is used for hot water temperature control.

[0056] The external heat exchanger side flow regulation valve 40 is selected by the control unit to allow hot water to flow, and is controlled so that the hot water temperature measured by the hot water temperature sensor 24 becomes the target value. In this way, by throttling the external heat exchanger side flow regulation valve 40 and allowing a small amount of hot water to flow, heat is released to the outside air and the cold water temperature is maintained.

[0057] This operation mode is shown in the table below.

[0058] <Hot water temperature control by compressor 10 [when outside air temperature is high (high thermal load)]> Figure 9 shows an operation mode for hot water temperature control by compressor 10 [when outside air temperature is high (high thermal load)]. This operation mode is for a case where the thermal load is greater than that of the operation mode shown in Figure 8. Note that this operation mode is similar to the operation mode shown in Figure 5, but differs in that the compressor 10 is used for hot water temperature control.

[0059] The vehicle air conditioner 1 shown in the figure performs dehumidifying and cooling by cooling operation that dissipates heat to outside air. The difference from the operating mode in Figure 8 is that the external heat exchanger side flow control valve 40 is changed from an intermediate opening to a fully open position, and the heater core side flow control valve 20 is changed from fully open to an intermediate opening position. The heater core side flow control valve 20 is controlled by the control unit so that the chilled water temperature measured by the chilled water temperature sensor 34 reaches a target value. In this way, by throttling the heater core side flow control valve 20 and increasing the hot water flow rate to the external heat exchanger 38, the amount of heat dissipated to the outside air is increased, and the chilled water temperature is maintained.

[0060] This operation mode is shown in the table below.

[0061] 10 shows a control flow of the compressor 10. The symbols in the following flowchart are as follows: Ta_h_A: Measurement value of the hot air temperature sensor 36 Ta_h_T: Heater core outlet air temperature target value Ta_c_A: Measurement value of the cold air temperature sensor 37 Ta_c_T: Cooler core outlet air temperature target value Tw_h_A: Measurement value of the hot water temperature sensor 24 Tw_h_T: Hot water temperature target value Tw_c_A: Measurement value of the cold water temperature sensor 34 Tw_c_T: Cold water temperature target value

[0062] The rotation speed of the compressor 10 is controlled by the control unit so that the hot water temperature or the chilled water temperature reaches a target value. In Fig. 10, in step S1, it is determined whether the measurement value Tw_h_A of the hot water temperature sensor 24 is smaller than the hot water temperature target value Tw_h_T and whether the measurement value Tw_c_A of the chilled water temperature sensor 34 is greater than the chilled water temperature target value Tw_c_T. If neither the hot water nor the chilled water has reached the target temperature (YES), the process proceeds to step S2, where the rotation speed of the compressor 10 is increased. Thereafter, the process proceeds to END and returns to START.

[0063] If the answer is NO in step S1, the process proceeds to step S3, where it is determined whether the measurement value Tw_h_A of the hot water temperature sensor 24 is greater than the hot water temperature target value Tw_h_T, or whether the measurement value Tw_c_A of the chilled water temperature sensor 34 is less than the chilled water temperature target value Tw_c_T. If either the hot water or the chilled water exceeds the target water temperature (YES), the process proceeds to step S4, where the rotation speed of the compressor 10 is reduced. After that, the process proceeds to END and returns to START again.

[0064] If the answer is NO in step S3, the process proceeds to END and returns to START. In this way, the rotation speed of the compressor 10 is controlled so that either the hot water or the cold water reaches the target temperature, thereby avoiding overshooting of the hot water temperature and undershooting of the cold water temperature.

[0065] 11 shows a control flow of the hot water pump 22. The hot water pump 22 is controlled by the control unit so that the outlet air temperature of the heater core 18 reaches a target value. In FIG. 11, in step S11, it is determined whether the measured value Ta_h_A of the hot air temperature sensor 36 is smaller than the heater core outlet air temperature target value Ta_h_T. If the outlet air temperature of the heater core 18 has not reached the target value (YES), the process proceeds to step S12, where the rotation speed of the hot water pump 22 is increased. Thereafter, the process proceeds to END and returns to START again.

[0066] If the answer is NO in step S11, the process proceeds to step S13, where it is determined whether the measured value Ta_h_A of the hot air temperature sensor 36 has exceeded the heater core outlet air temperature target value Ta_h_T. If the outlet air temperature of the heater core 18 has exceeded the target value (YES), the process proceeds to step S14, where the rotation speed of the hot water pump 22 is reduced. Thereafter, the process proceeds to END and returns to START again.

[0067] As described above, by adjusting the rotation speed of the hot water pump 22, the outlet air temperature of the heater core 18 is controlled to reach a target value.

[0068] 12 shows a control flow of the chilled water pump 32. The chilled water pump 32 is controlled by the control unit so that the outlet air temperature of the cooler core 28 reaches a target value. In FIG. 12, in step S21, it is determined whether the measurement value Ta_c_A of the chilled air temperature sensor 37 is greater than the cooler core outlet air temperature target value Ta_c_T. If the outlet air temperature of the cooler core 28 has not reached the target value (YES), the process proceeds to step S22, where the rotation speed of the chilled water pump 32 is increased. Thereafter, the process proceeds to END and returns to START again.

[0069] If the answer is NO in step S21, the process proceeds to step S23, where it is determined whether the measurement value Ta_c_A of the coolant temperature sensor 37 exceeds the cooler core outlet air temperature target value Ta_c_T. If the outlet air temperature of the cooler core 28 exceeds the target value (YES), the process proceeds to step S24, where the rotation speed of the coolant pump 32 is reduced. Thereafter, the process proceeds to END and returns to START again.

[0070] As described above, by adjusting the rotation speed of the chilled water pump 32, the outlet air temperature of the cooler core 28 is controlled to reach the target value.

[0071] 13A and 13B show the control flows for the flow regulation valves 20, 30, and 40. The control unit controls the opening of each flow regulation valve 20, 30, and 40 so that the other of the hot water temperature and chilled water temperature that have reached their target values ​​in the compressor 10 remains at their target values. In FIG. 13A , in step S31, it is determined whether the measurement value Tw_h_A of the hot water temperature sensor 24 is smaller than the hot water temperature target value Tw_h_T and whether the measurement value Tw_c_A of the chilled water temperature sensor 34 is equal to or smaller than the chilled water temperature target value Tw_c_T. If the hot water temperature has not reached its target value and the chilled water temperature has reached its target value (YES), the process proceeds to step S32, where the flow regulation valves 20, 30, and 40 are controlled to control the hot water temperature to the target value.

[0072] In step S32, it is determined whether hot water is flowing through the external heat exchanger 38. If hot water is flowing through the external heat exchanger 38 (YES), that is, if the cooling mode is selected, the process proceeds to step S32-1, where it is determined whether the heater core side flow regulation valve 20 is fully open. If the heater core side flow regulation valve 20 is not fully open (NO), the process proceeds to step S33-1, where the opening of the heater core side flow regulation valve 20 is increased. Thereafter, the process proceeds to END and returns to START. If the heater core side flow regulation valve 20 is fully open in step S32-1 (YES), the process proceeds to step S34-1, where the opening of the hot water side of the external heat exchanger side flow regulation valve 40 is reduced.

[0073] If, in step S32, hot water is not flowing through the external heat exchanger 38 (NO), i.e., if the system is in heat pump mode, the process proceeds to step S32-2, where it is determined whether the external heat exchanger-side flow regulation valve 40 is fully open to the chilled water side. If the external heat exchanger-side flow regulation valve 40 is not fully open to the chilled water side (NO), the process proceeds to step S33-2, where the chilled water side opening of the external heat exchanger-side flow regulation valve 40 is increased. The process then proceeds to END and returns to START. If, in step S32-2, the external heat exchanger-side flow regulation valve 40 is fully open to the chilled water side (YES), the process proceeds to step S34-2, where the opening of the cooler core-side flow regulation valve 30 is reduced. This increases the proportion of chilled water flowing through the external heat exchanger 38 as much as possible, thereby increasing the amount of heat absorbed by the external heat exchanger 38. The process then proceeds to END and returns to START.

[0074] If the answer is NO in step S31, the process proceeds to step S35, where it is determined whether the measurement value Tw_c_A of the chilled water temperature sensor 34 is greater than the chilled water temperature target value Tw_c_T and whether the measurement value Tw_h_A of the hot water temperature sensor 24 is greater than or equal to the hot water temperature target value Tw_h_T. If the chilled water temperature has not reached the target value and the hot water temperature has reached the target value (YES), the process proceeds to step S36, where the chilled water temperature is controlled by the flow adjustment valves 20, 30, 40 to reach the target value.

[0075] In step S36, it is determined whether or not chilled water is flowing through the external heat exchanger 38. If chilled water is flowing through the external heat exchanger 38 (YES), that is, if the system is in heat pump mode, the process proceeds to step S36-1, where it is determined whether or not the cooler core side flow regulation valve 30 is fully open. If the cooler core side flow regulation valve 30 is not fully open (NO), the process proceeds to step S37-1, where the opening of the cooler core side flow regulation valve 30 is increased. Thereafter, the process proceeds to END and returns to START. If the cooler core side flow regulation valve 30 is fully open in step S36-1 (YES), the process proceeds to step S38-1, where the opening of the chilled water side of the external heat exchanger side flow regulation valve 40 is reduced.

[0076] If, in step S36, cold water is not flowing through the external heat exchanger 38 (NO), i.e., if the cooling mode is selected, the process proceeds to step S36-2, where it is determined whether the external heat exchanger-side flow regulation valve 40 is fully open to the hot water side. If the external heat exchanger-side flow regulation valve 40 is not fully open to the hot water side (NO), the process proceeds to step S37-2, where the opening degree of the hot water side of the external heat exchanger-side flow regulation valve 40 is increased. The process then proceeds to END and returns to START. If, in step S36-2, the external heat exchanger-side flow regulation valve 40 is fully open to the hot water side (YES), the process proceeds to step S38-2, where the opening degree of the heater core-side flow regulation valve 20 is reduced. This increases the proportion of hot water flowing through the external heat exchanger 38 as much as possible, thereby increasing the amount of heat dissipated by the external heat exchanger 38. The process then proceeds to END and returns to START.

[0077] In this way, when either the hot water or the cold water reaches the target temperature by controlling the compressor speed as shown in Figure 10, the flow control valves 20, 30, and 40 are controlled so that the temperature of the other water reaches the target temperature.

[0078] The effects of the present embodiment described above are as follows. To perform dehumidifying heating or dehumidifying cooling, hot water is circulated through the heater core 18 and cold water is circulated through the cooler core 28. By controlling the flow rates of the hot water pump 22 and the cold water pump 32 and the openings of the heater core side flow regulation valve 20, the cooler core side flow regulation valve 30, and the external heat exchanger side flow regulation valve 40, the flow rates of the cold water flowing through each core 18, 28 are kept above a predetermined value and are set to a target value. This prevents the cold water flowing through the heater core 18 and the cooler core 28 from falling below the predetermined value, thereby preventing uneven distribution of the cold water within the heater core 18 and the cooler core 28 or a temperature difference between the upstream and downstream sides of the cold water, resulting in a distribution of air temperature.

[0079] Either the temperature of the hot water that has undergone heat exchange in the condenser 11 or the temperature of the cold water that has undergone heat exchange in the evaporator 13 is controlled by the rotation speed of the compressor 10, and the other is controlled by the heat exchange amount of the external heat exchanger 38. This makes it possible to control the temperatures of both the hot water and the cold water without overshooting or undershooting.

[0080] When the heat load is large, for example, when the outside air temperature is lower or higher than a predetermined value, the opening of the external heat exchanger-side flow regulation valve 40 is controlled to be increased (steps S33-2, S34-2, S37-2, and S38-2 in FIGS. 13A and 13B), thereby increasing the amount of heat absorbed or released as much as possible and increasing capacity. In addition, by increasing the valve opening and reducing fluid loss at the external heat exchanger-side flow regulation valve 40, the pump power can be reduced and the COP can be improved.

[0081] Second Embodiment Next, a second embodiment of the present disclosure will be described. In this embodiment, the same vehicle air conditioner 1 as in the first embodiment is used, but in a different operating mode.

[0082] <Heavy-load dehumidifying and heating operation [when the outdoor temperature is even lower (maximum heat load)]> Fig. 14 shows an operation mode of heavy-load dehumidifying and heating operation [when the outdoor temperature is even lower (maximum heat load)]. This mode is an operation mode when the heat load is even greater (maximum heat load) than the case in which the heat load is large in the heating and dehumidifying operation described with reference to Figs. 2 and 6.

[0083] The vehicle air conditioner 1 shown in the figure performs dehumidifying and heating by operating a heat pump that absorbs heat from outside air.

[0084] The rotation speed of the compressor 10 is controlled by the control unit so that the hot water temperature measured by the hot water temperature sensor 24 becomes a target value.

[0085] The rotation speed of the chilled water pump 32 is set to the maximum rotation speed by the control unit in order to supply a larger amount of chilled water to the external heat exchanger 38 and maximize the amount of heat absorption.

[0086] The rotation speed of the hot water pump 22 is controlled by the control unit so that the heater core outlet air temperature measured by the hot air temperature sensor 36 reaches a target value.

[0087] The heater core side flow adjustment valve 20 is fully opened by the control unit, thereby performing heating corresponding to a large heat load.

[0088] The cooler core-side flow adjustment valve 30 controls the cooler core-side upstream three-way valve 30a via a control unit to mix hot water with cold water. As a result, a mixture of cold water and hot water is guided to the cooler core 28. In FIG. 14 , the flow path through which the mixture flows is indicated by a thick dashed line (the same applies to the notation for a mixture of cold water and hot water below). The opening of the cooler core-side upstream three-way valve 30a is controlled so that the cooler core outlet air temperature measured by the air temperature sensor 37 is 0°C or higher. This prevents frosting in the cooler core 28. Furthermore, mixing cold water and hot water increases the flow rate, ensuring that the coolant flow rate flowing to the cooler core 28 is at or above a predetermined value.

[0089] The external heat exchanger side flow regulation valve 40 is selected by the control unit to allow cold water to flow and is fully open, thereby supplying cold water below 0°C to the external heat exchanger 38, which absorbs a large amount of heat from the outside air to accommodate a large heat load.

[0090] The cold water flows from the cooler core side heat medium circulation flow path 7 to the heater core side heat medium circulation flow path 5 through the bypass flow path 42. This is because the cold water flows in such a way as to eliminate the imbalance in the heat medium flow rate (coolant flow rate) between the heater core side heat medium circulation flow path 5 and the cooler core side heat medium circulation flow path 7 caused by mixing the cold water with hot water by the cooler core side upstream three-way valve 30a.

[0091] This operation mode is shown in the table below.

[0092] 15 shows an operation mode in which the defrosting and dehumidifying operation is performed when the external heat exchanger 38 is determined to have frost. The control unit determines whether the external heat exchanger 38 has frost, using a frost sensor or the like provided in the external heat exchanger 38.

[0093] The rotation speed of the compressor 10 is controlled by the control unit so that the chilled water temperature measured by the chilled water temperature sensor 34 becomes a target value.

[0094] The rotation speed of the chilled water pump 32 is controlled by the control unit so that the cooler core outlet air temperature measured by the chilled air temperature sensor 37 becomes a target temperature.

[0095] The rotation speed of the hot water pump 22 is controlled by the control unit so that the heater core outlet air temperature measured by the hot air temperature sensor 36 reaches a target value.

[0096] The external heat exchanger side flow regulation valve 40 is selected by the control unit to allow hot water to flow and is fully open, whereby defrosting is performed by the hot water in the external heat exchanger 38.

[0097] The cooler core side flow adjustment valve 30 is fully opened by the control unit. Cold water of 0° C. or higher is introduced into the cooler core 28, thereby preventing frost.

[0098] The opening of the heater core side flow adjustment valve 20 is controlled by the control unit so that the hot water temperature measured by the hot water temperature sensor 24 becomes a target value, thereby ensuring heating capacity.

[0099] The heater core side downstream three-way valve 20b is controlled by the control unit to open to mix a portion of the hot water with the cold water. As a result, a mixture of cold water and hot water is guided from the downstream side of the heater core 18 to the evaporator 13 (see the thick dashed line). By flowing mixed water at a higher temperature than the cold water through the evaporator 13, the low pressure is increased, and the capacity of the compressor 10 is increased, making it possible to raise the hot water temperature.

[0100] The cold water flows from the cooler core side heat medium circulation flow path 7 to the heater core side heat medium circulation flow path 5 through the bypass flow path 42. This is because the cold water flows in such a way as to eliminate the imbalance in the heat medium flow rate (coolant flow rate) between the heater core side heat medium circulation flow path 5 and the cooler core side heat medium circulation flow path 7 caused by mixing the cold water with hot water by the heater core side downstream three-way valve 20b.

[0101] In this operation mode, the heating capacity can be increased by keeping the cold water temperature at 0°C or higher, mixing hot water and cold water through the heater core side downstream three-way valve 20b, and increasing the low pressure of the evaporator 13. As a result, defrosting is performed by flowing hot water through the external heat exchanger 38 while maintaining the blown air temperature during heating.

[0102] This operation mode is shown in the table below. In the above-described operation modes, the compressor 10 controls the chilled water temperature, but the compressor 10 may also control the hot water temperature. Also, the heater core side flow adjustment valve 20 may control the chilled water temperature.

[0103] <Frost-avoiding dehumidifying operation [during continuous operation after defrosting of external heat exchanger 38]> FIG. 16 shows an operation mode of the frost-avoiding dehumidifying operation that is performed after defrosting of the external heat exchanger 38.

[0104] The rotation speed of the compressor 10 is controlled by the control unit so that the chilled water temperature measured by the chilled water temperature sensor 34 becomes a target value.

[0105] The rotation speed of the chilled water pump 32 is controlled by the control unit so that the cooler core outlet air temperature measured by the chilled air temperature sensor 37 becomes a target temperature.

[0106] The rotation speed of the hot water pump 22 is controlled by the control unit so that the heater core outlet air temperature measured by the hot air temperature sensor 36 reaches a target value.

[0107] The external heat exchanger-side flow regulation valve 40 is selected by the control unit to allow cold water to flow and is fully open. Cold water above 0°C flows through the external heat exchanger 38, preventing frost from forming again. When the outside air temperature is below 0°C, the external heat exchanger 38 cannot absorb heat, so the external heat exchanger-side flow regulation valve 40 is fully closed to prevent cold water from flowing.

[0108] The cooler core side flow regulation valve 30 is set to the minimum opening by the control unit. By setting the cooler core side flow regulation valve 30 to the minimum opening, as much cold water as possible is passed through the external heat exchanger 38 to ensure the amount of heat absorption. Cold water of 0°C or higher is introduced into the cooler core 28, preventing frost. When the external heat exchanger side flow regulation valve 40 is fully closed, the cooler core side flow regulation valve 30 is fully opened.

[0109] The opening degree of the heater core side flow adjustment valve 20 is controlled by the control unit so that the hot water temperature measured by the hot water temperature sensor 24 becomes a target value.

[0110] The heater core side downstream three-way valve 20b is controlled by the control unit to open to mix a portion of the hot water with the cold water. As a result, a mixture of cold water and hot water is guided from the downstream side of the heater core 18 to the evaporator 13 (see the thick dashed line). By flowing mixed water at a higher temperature than the cold water through the evaporator 13, the low pressure is increased, and the capacity of the compressor 10 is increased, making it possible to raise the hot water temperature.

[0111] The cold water flows from the cooler core side heat medium circulation flow path 7 to the heater core side heat medium circulation flow path 5 through the bypass flow path 42. This is because the cold water flows in such a way as to eliminate the imbalance in the heat medium flow rate (coolant flow rate) between the heater core side heat medium circulation flow path 5 and the cooler core side heat medium circulation flow path 7 caused by mixing the cold water with hot water by the heater core side downstream three-way valve 20b.

[0112] In this operating mode, after defrosting the external heat exchanger 38, the cold water temperature is kept above 0°C to prevent frost from forming again in the external heat exchanger 38, and while absorbing heat from the external heat exchanger 38, hot water and cold water are mixed in the heater core side downstream three-way valve 20b, and the low pressure of the evaporator 13 is increased, thereby increasing the heating capacity.

[0113] This operation mode is shown in the table below.

[0114] In the above-described operation modes, the compressor 10 controls the chilled water temperature, but the compressor 10 may also control the hot water temperature. Also, the heater core side flow adjustment valve 20 may control the chilled water temperature.

[0115] <Heavy-load dehumidifying and cooling operation [when the outdoor temperature is even higher (maximum heat load)]> Fig. 17 shows an operation mode of heavy-load dehumidifying and heating operation [when the outdoor temperature is even lower (maximum heat load)]. This mode is an operation mode when the heat load is even higher (maximum heat load) than the high heat load cases in the dehumidifying and cooling operation described with reference to Figs. 5 and 9.

[0116] The vehicle air conditioner 1 shown in the figure performs dehumidifying and cooling by cooling operation in which heat is released to the outside air.

[0117] The rotation speed of the compressor 10 is controlled by the control unit so that the chilled water temperature measured by the chilled water temperature sensor 34 becomes a target value.

[0118] The rotation speed of the chilled water pump 32 is controlled by the control unit so that the cooler core outlet air temperature measured by the chilled air temperature sensor 37 becomes a target value.

[0119] The rotation speed of the hot water pump 22 is set to the maximum rotation speed by the control unit in order to supply as much hot water as possible to the external heat exchanger 38 and maximize the amount of heat radiation.

[0120] The external heat exchanger side flow regulation valve 40 is selected by the control unit to allow hot water to flow and is fully open, thereby dissipating a large amount of heat to the outside air in order to cope with the large heat load in the external heat exchanger 38.

[0121] The cooler core side flow adjustment valve 30 is fully opened by the control unit, thereby performing cooling corresponding to a large heat load.

[0122] The heater core side flow adjustment valve 20 controls the heater core side upstream three-way valve 20a via a control unit to mix cold water with hot water. This causes the mixed water of cold water and hot water to be guided to the heater core 18 (see the thick dashed line). By flowing the mixed water through the heater core 18, the temperature rise of the hot water is suppressed while the coolant flow rate to the heater core 18 is ensured to be equal to or greater than a predetermined value. The opening of the heater core side upstream three-way valve 20a is controlled so that the heater core outlet air temperature measured by the hot air temperature sensor 36 reaches a target value.

[0123] The hot water flows from the heater core side heat medium circulation flow path 5 to the cooler core side heat medium circulation flow path 7 through the bypass flow path 42. This is because the hot water flows in such a way as to eliminate the imbalance in the heat medium flow rate (coolant flow rate) between the heater core side heat medium circulation flow path 5 and the cooler core side heat medium circulation flow path 7 caused by mixing the hot water with cold water by the heater core side upstream three-way valve 20a.

[0124] In this operating mode, when the outside air temperature is high and the heat load is even greater, the heater core side flow control valve 20 mixes hot water and cold water, suppressing the temperature rise of the hot water flowing into the heater core 18 while raising the hot water temperature to the external heat exchanger 38, thereby increasing the amount of heat released into the outside air.

[0125] This operation mode is shown in the table below.

[0126] Next, the control flow of the operation modes of this embodiment will be described with reference to Figures 18A to 18C. This flowchart is the same as the flowcharts of Figures 13A and 13B, except that each operation mode of this embodiment has been added.

[0127] In step S41, it is determined whether or not frost has formed in the external heat exchanger 38. If frost has formed (YES), the process proceeds to step S42, where the flag Deice_Flag is set to ON. Then, the process proceeds to step S43, where the defrosting and dehumidifying operation described with reference to FIG. 15 is performed.

[0128] If it is determined in step S41 that there is no frost (NO), the process proceeds to step S44, where it is determined whether the flag Deice_Flag is on. If the flag Deice_Flag is on and there is a determination that there is frost on the external heat exchanger 38 at least once during operation (YES), the process proceeds to step S45, and the frost avoidance dehumidification operation described in FIG. 16 is performed.

[0129] If the answer is NO in step S44, the process proceeds to step S46, where it is determined whether the measurement value Tw_h_A of the hot water temperature sensor 24 is smaller than the hot water temperature target value Tw_h_T and whether the measurement value Tw_c_A of the cold water temperature sensor 34 is equal to or smaller than the cold water temperature target value Tw_c_T. If the hot water temperature has not reached the target value and the cold water temperature has reached the target value (YES), the process proceeds to step S47, where the hot water temperature is controlled by the flow adjustment valves 20, 30, 40 to reach the target value.

[0130] In step S47, it is determined whether hot water is flowing through the external heat exchanger 38. If hot water is flowing through the external heat exchanger 38 (YES), that is, if the cooling mode is selected, the process proceeds to step S47-1, where it is determined whether the heater core side flow regulation valve 20 is fully open. If the heater core side flow regulation valve 20 is not fully open (NO), the process proceeds to step S48-1, where the opening of the heater core side flow regulation valve 20 is increased. Thereafter, the process proceeds to END and returns to START. If the heater core side flow regulation valve 20 is fully open in step S47-1 (YES), the process proceeds to step S48-2, where the opening of the external heat exchanger side flow regulation valve 40 is decreased.

[0131] If, in step S47, hot water is not flowing through the external heat exchanger 38 (NO), i.e., if the system is in heat pump mode, the process proceeds to step S47-2, where it is determined whether the external heat exchanger-side flow regulation valve 40 is fully open to the chilled water side. If the external heat exchanger-side flow regulation valve 40 is not fully open to the chilled water side (NO), the process proceeds to step S48-3, where the opening of the external heat exchanger-side flow regulation valve 40 is increased to the chilled water side. Thereafter, the process proceeds to END and returns to START. If, in step S47-2, the external heat exchanger-side flow regulation valve 40 is fully open to the chilled water side (YES), the process proceeds to step S49, where it is determined whether the cooler-core-side flow regulation valve 30 is at its minimum opening. If the cooler-core-side flow regulation valve 30 is not at its minimum opening (NO), the process proceeds to step S50, where the opening of the cooler-core-side flow regulation valve 30 is reduced. Thereafter, the process proceeds to END and returns to START.

[0132] If the cooler core side flow adjustment valve 30 has reached the minimum opening (YES), the process proceeds to step S51, and the high load dehumidifying and heating operation described with reference to FIG. 14 is performed.

[0133] 18C, it is determined whether the measured value Tw_c_A of the chilled water temperature sensor 34 is greater than the target chilled water temperature value Tw_c_T and whether the measured value Tw_h_A of the hot water temperature sensor 24 is greater than or equal to the target hot water temperature value Tw_h_T. If the chilled water temperature has not reached the target value and the hot water temperature has reached the target value (YES), it proceeds to step S53, and the flow adjustment valves 20, 30, 40 are controlled to adjust the chilled water temperature to the target value.

[0134] In step S53, it is determined whether or not chilled water is flowing through the external heat exchanger 38. If chilled water is flowing through the external heat exchanger 38 (YES), that is, if the system is in heat pump mode, the process proceeds to step S53-1, where it is determined whether or not the cooler core side flow regulation valve 30 is fully open. If the cooler core side flow regulation valve 30 is not fully open (NO), the process proceeds to step S54-1, where the opening of the cooler core side flow regulation valve 30 is increased. Thereafter, the process proceeds to END and returns to START again. If the cooler core side flow regulation valve 30 is fully open in step S53-1 (YES), the process proceeds to step S54-2, where the opening of the chilled water side of the external heat exchanger side flow regulation valve 40 is reduced.

[0135] If, in step S53, cold water is not flowing through the external heat exchanger 38 (NO), i.e., if the cooling mode is selected, the process proceeds to step S53-2, where it is determined whether the external heat exchanger-side flow regulation valve 40 is fully open to the hot water side. If the external heat exchanger-side flow regulation valve 40 is not fully open to the hot water side (NO), the process proceeds to step S54-3, where the opening degree of the hot water side of the external heat exchanger-side flow regulation valve 40 is increased. The process then proceeds to END and returns to START. If, in step S53-2, the external heat exchanger-side flow regulation valve 40 is fully open (YES), the process proceeds to step S55, where it is determined whether the heater core-side flow regulation valve 20 is at its minimum opening. If the heater core-side flow regulation valve 20 is not at its minimum opening (NO), the process proceeds to step S56, where the opening degree of the heater core-side flow regulation valve 20 is reduced. The process then proceeds to END and returns to START.

[0136] If the heater core side flow adjustment valve 20 has reached the minimum opening (YES), the process proceeds to step S57, and the high load dehumidifying and cooling operation described with reference to FIG. 17 is performed.

[0137] If NO in step S52, the process proceeds to END and returns to START again.

[0138] The above-described embodiment has the following advantages. The cooler core 28 is introduced with cold water flowing through the cooler-core-side heat medium circulation passage 7, and a portion of the warm water flowing through the heater-core-side heat medium circulation passage 5 is mixed with the cold water. This allows the temperature of the heat medium flowing through the cooler core 28 to be 0°C or higher, preventing frosting of the cooler core 28.

[0139] Defrosting operation is performed by flowing hot water from the heater core side heat medium circulation flow path 5 to the external heat exchanger 38. At this time, the external heat exchanger 38 cannot absorb heat, resulting in insufficient heating capacity, but by supplying part of the hot water flowing out from the heater core 18 to the cooler core side heat medium circulation flow path 7, the coolant temperature exchanging heat with the evaporator 13 is raised, thereby increasing the low pressure of the refrigeration cycle. This allows the heating capacity to be maintained.

[0140] After the defrost operation is completed, cold water is circulated from the cooler core-side heat medium circulation passage 7 to the external heat exchanger 38 to return to heat pump operation. At this time, to prevent frost from forming again in the external heat exchanger 38, the temperature of the cold water circulated in the external heat exchanger 38 is controlled to be 0°C or higher. On the other hand, there is a risk that the external heat exchanger 38 will not absorb enough heat and the heating capacity will be insufficient. However, by supplying a portion of the hot water flowing out from the heater core 18 to the cooler core-side heat medium circulation passage 7, the temperature of the coolant exchanging heat with the evaporator 13 is increased, thereby raising the low pressure of the refrigeration cycle. This makes it possible to maintain the heating capacity.

[0141] During dehumidifying and cooling, hot water is supplied to the external heat exchanger 38 from the heater core side heat medium circulation flow path 5, and heat is dissipated to the outside air. At this time, part of the cold water flowing through the cooler core side heat medium circulation flow path 7 is made to flow through the heater core 18. This makes it possible to increase the hot water temperature at the outlet of the condenser 11 while suppressing a temperature rise in the coolant flowing through the heater core 18, and to increase the amount of heat dissipated in the external heat exchanger 38.

[0142] The vehicle air conditioner and the control method thereof described in each of the above-described embodiments can be understood, for example, as follows.

[0143] A vehicle air conditioning system (1) according to a first aspect of the present disclosure includes a refrigeration cycle (3) having a compressor (10) that compresses a refrigerant, a condenser (11) that condenses the refrigerant compressed by the compressor, an expansion valve (12) that expands the refrigerant condensed by the condenser, and an evaporator (13) that evaporates the refrigerant expanded by the expansion valve, a cooler core (28) that cools air to be introduced into a vehicle compartment, a heater core (18) that heats the air to be introduced into the vehicle compartment, and a cooling system (19) for cooling the air to be introduced into the vehicle compartment. a cooler core side heat medium circulation flow path (7) for circulating a heat medium between the heater core and the evaporator; a heater core side heat medium circulation flow path (5) for circulating a heat medium between the heater core and the condenser; an external heat exchanger (38) for exchanging heat between the heat medium introduced from the cooler core side heat medium circulation flow path or the heater core side heat medium circulation flow path and outside air; a cooler core side pump (32) provided in the cooler core side heat medium circulation flow path for circulating the heat medium; A heater core side pump (22) provided in a heater core side heat medium circulation flow path for circulating the heat medium, a cooler core side flow regulation valve (30) for regulating the flow rate of the heat medium flowing through the cooler core, a heater core side flow regulation valve (20) for regulating the flow rate of the heat medium flowing through the heater core, an external heat exchanger side flow regulation valve (40) for regulating the flow rate of the heat medium flowing through the external heat exchanger, and and a control unit that controls the cooler core side pump and the heater core side pump, as well as the opening degrees of the cooler core side flow regulation valve, the heater core side flow regulation valve, and the external heat exchanger side flow regulation valve to perform dehumidifying heating or dehumidifying cooling, and the control unit controls the flow rates of the cooler core side pump and the heater core side pump, and the cooler core side flow regulation valve, the heater core side flow regulation valve, and the external heat exchanger side flow regulation valve so that the flow rates of the heat medium flowing through the cooler core and the heat medium flowing through the heater core do not fall below a predetermined value and reach a target value.

[0144] A heat medium is circulated through the cooler core and the heater core to perform dehumidifying heating or dehumidifying cooling. By controlling the flow rates of the cooler core-side pump and the heater core-side pump and the openings of the cooler core-side flow control valve, heater core-side flow control valve, and external heat exchanger-side flow control valve, the flow rate of the heat medium flowing through each core is prevented from falling below a predetermined value and is set to a target value. This prevents the heat medium flowing through the cooler core and the heater core from falling below the predetermined value, resulting in uneven distribution of the heat medium liquid inside the cooler core and the heater core, or a temperature difference between the upstream and downstream sides of the heat medium, causing a distribution in the air temperature. For example, even when the opening of the external heat exchanger-side flow control valve is fully opened to increase the amount of heat absorption or release in the external heat exchanger, the flow rate of the cooler core-side pump or the heater-side pump is increased to prevent the heat medium flow rate through the cooler core and the heater core from falling below the predetermined value.

[0145] In the vehicle air conditioning system according to the second aspect of the present disclosure, in the first aspect, the control unit controls the rotation speed of the compressor so that the temperature of either the heat medium that has undergone heat exchange in the condenser or the heat medium that has undergone heat exchange in the evaporator becomes a target value, and also controls the heat exchange amount of the external heat exchanger so that the temperature of the other of the heat medium that has undergone heat exchange in the condenser or the heat medium that has undergone heat exchange in the evaporator becomes a target value.

[0146] Either the temperature of the heat medium (hot heat medium) heat-exchanged in the condenser or the temperature of the heat medium (cold heat medium) heat-exchanged in the evaporator is controlled by the compressor rotation speed, and the other is controlled by the heat exchange amount of the external heat exchanger. This allows the temperatures of both the hot heat medium and the cold heat medium to be controlled without overshooting or undershooting. The heat exchange amount of the external heat exchanger can be controlled by the opening of the external heat exchanger side flow control valve, the cooler core side pump, the heater core side pump, etc.

[0147] In the vehicle air conditioning device according to the third aspect of the present disclosure, in the second aspect, when the heat load is greater than a predetermined value, the control unit controls the external heat exchanger side flow control valve to increase the opening degree so that the temperature of the other heat medium becomes a target value.

[0148] When the heat load is greater than a predetermined value, the opening of the external heat exchanger side flow regulation valve can be controlled to increase, thereby increasing the heat absorption or heat release amount as much as possible and increasing the capacity. Furthermore, increasing the valve opening reduces fluid loss in the flow regulation valve, thereby reducing pump power and improving COP. Here, a heat load greater than a predetermined value refers to, for example, a case where the outdoor air temperature is lower than the outdoor air temperature expected in normal heating operation, or a case where the outdoor air temperature is higher than the outdoor air temperature expected in normal cooling operation.

[0149] In the vehicle air conditioning device according to a fourth aspect of the present disclosure, in any one of the first to third aspects, the control unit causes a portion of the heat medium flowing through the heater core side heat medium circulation flow path to flow into the cooler core.

[0150] The heat transfer medium (cold heat transfer medium) flowing through the heat transfer medium circulation passage on the cooler core side is introduced to the cooler core, but a portion of the heat transfer medium (hot heat transfer medium) flowing through the heat transfer passage on the heater core side is mixed in. This allows the temperature of the heat transfer medium flowing through the cooler core to be maintained above 0°C, preventing frost on the cooler core.

[0151] In the vehicle air conditioning device according to a fifth aspect of the present disclosure, in any one of the first to fourth aspects, when a heat medium is caused to flow from the heater core side heat medium circulation flow path to the external heat exchanger to perform defrosting operation, the control unit supplies a portion of the heat medium flowing out from the heater core to the cooler core side heat medium circulation flow path.

[0152] Defrosting is performed by flowing the heat transfer medium (hot heat transfer medium) from the heater core side heat transfer medium circulation flow path to the external heat exchanger. At this time, the external heat exchanger cannot absorb heat, resulting in insufficient heating capacity, but by supplying some of the heat transfer medium flowing out of the heater core to the cooler core side heat transfer medium circulation flow path, the temperature of the heat transfer medium exchanging heat with the evaporator is raised, increasing the low pressure of the refrigeration cycle. This allows the heating capacity to be maintained.

[0153] In the vehicle air conditioning device according to a sixth aspect of the present disclosure, in the fifth aspect, after the defrosting operation is completed, the control unit causes the heat medium to flow from the cooler core side heat medium circulation flow path to the external heat exchanger at a temperature of 0°C or higher, and supplies a portion of the heat medium flowing out from the heater core to the cooler core side heat medium circulation flow path.

[0154] After the defrost operation ends, the heat pump operation is resumed by flowing the heat transfer medium (cold heat transfer medium) from the cooler core side heat transfer medium circulation passage to the external heat exchanger. At this time, to prevent frost from forming again in the external heat exchanger, the temperature of the heat transfer medium flowing through the external heat exchanger is controlled to be 0°C or higher. While there is a risk of insufficient heat absorption in the external heat exchanger, resulting in insufficient heating capacity, some of the heat transfer medium flowing out of the heater core is supplied to the cooler core side heat transfer medium circulation passage, thereby raising the temperature of the heat transfer medium exchanging heat with the evaporator and increasing the low pressure of the refrigeration cycle. This allows the heating capacity to be maintained.

[0155] In the vehicle air conditioning device according to a seventh aspect of the present disclosure, in any one of the first to sixth aspects, the control unit causes a portion of the heat medium flowing through the cooler core side heat medium circulation flow path to flow into the heater core when the heat medium from the heater core side heat medium circulation flow path is supplied to the external heat exchanger.

[0156] During dehumidifying and cooling, a heat transfer medium (hot heat transfer medium) is supplied to the external heat exchanger from the heater core side heat transfer medium circulation passage and heat is dissipated to the outside air. At this time, a portion of the heat transfer medium flowing through the cooler core side heat transfer medium circulation passage is diverted to the heater core. This makes it possible to increase the temperature of the hot water at the condenser outlet while suppressing the increase in the temperature of the hot water flowing through the heater core, thereby increasing the amount of heat absorbed by the external heat exchanger.

[0157] In the vehicle air conditioning device according to an eighth aspect of the present disclosure, in any one of the first to seventh aspects, a bypass flow path (42) through which a heat medium flows is provided between the cooler core side heat medium circulation flow path and the heater core side heat medium circulation flow path.

[0158] By providing a bypass flow path through which the heat medium flows between the cooler core side heat medium circulation flow path and the heater core side heat medium circulation flow path, it is possible to adjust the imbalance in the flow rate of the heat medium flowing through the cooler core side heat medium circulation flow path and the heater core side heat medium circulation flow path. Note that a reserve tank for storing the heat medium may be provided in the bypass flow path.

[0159] A control method for a vehicle air conditioner according to a first aspect of the present disclosure includes a refrigeration cycle having a compressor that compresses a refrigerant, a condenser that condenses the refrigerant compressed by the compressor, an expansion valve that expands the refrigerant condensed by the condenser, and an evaporator that evaporates the refrigerant expanded by the expansion valve, a cooler core that cools air to be introduced into a vehicle compartment, a heater core that heats the air to be introduced into the vehicle compartment, a cooler core side heat medium circulation flow path that circulates a heat medium between the cooler core and the evaporator, a heater core side heat medium circulation flow path that circulates a heat medium between the heater core and the condenser, an external heat exchanger that exchanges heat between the heat medium introduced from the cooler core side heat medium circulation flow path or the heater core side heat medium circulation flow path and outside air, and a control circuit for controlling the cooler core side heat medium circulation flow path. a cooler core side pump provided in the heater core side heat medium circulation flow path for circulating the heat medium; a heater core side pump provided in the heater core side heat medium circulation flow path for circulating the heat medium; a cooler core side flow control valve for adjusting the flow rate of the heat medium flowing through the cooler core; a heater core side flow control valve for adjusting the flow rate of the heat medium flowing through the heater core; and an external heat exchanger side flow control valve for adjusting the flow rate of the heat medium flowing through the external heat exchanger, wherein the flow rates of the cooler core side pump and the heater core side pump, as well as the openings of the cooler core side flow control valve, the heater core side flow control valve, and the external heat exchanger side flow control valve are controlled so that the flow rates of the heat medium flowing through the cooler core and the heat medium flowing through the heater core do not fall below predetermined values ​​and reach target values.

[0160] REFRIGERATION CYCLE 1 VEHICLE AIR CONDITIONER 3 REFRIGERATION CYCLE 5 HEATER CORE SIDE HEAT TRANSFER CIRCULATION FLOW CHANNEL 7 COOLER CORE SIDE HEAT TRANSFER CIRCULATION FLOW CHANNEL 10 COMPRESSOR 11 CONDENSER 12 EXPANSION VALVE 13 EVAPORATOR 14 ACCUMULATOR 18 HEATER CORE 20 HEATER CORE SIDE FLUX 20A HEATER CORE SIDE UPPER 3-WAY VALVE 20B HEATER CORE SIDE DOWNPER 3-WAY VALVE 22 HOT WATER PUMP (HEATER CORE SIDE PUMP) 24 HOT WATER TEMPERATURE SENSOR 28 COOLER CORE 30 COOLER CORE SIDE FLUX 30A COOLER CORE SIDE UPPER 3-WAY VALVE 30B COOLER CORE SIDE DOWNPER 3-WAY VALVE 32 COLD WATER PUMP (COOLER CORE SIDE PUMP) 34 COLD WATER TEMPERATURE SENSOR 36 HOT AIR TEMPERATURE SENSOR 37 COLD AIR TEMPERATURE SENSOR 38 EXTERNAL HEAT EXCHANGER 40 EXTERNAL HEAT EXCHANGER SIDE FLUX 40A EXTERNAL HEAT EXCHANGER SIDE UPPER 3-WAY VALVE 40b External heat exchange side downstream three-way valve 42 Bypass flow path 44 Reserve tank

Claims

1. A refrigeration cycle having a compressor that compresses a refrigerant, a condenser that condenses the refrigerant compressed by the compressor, an expansion valve that expands the refrigerant condensed by the condenser, and an evaporator that evaporates the refrigerant expanded by the expansion valve; a cooler core that cools air to be introduced into a passenger compartment; a heater core that heats the air to be introduced into the passenger compartment; a cooler core side heat medium circulation flow path that circulates a heat medium between the cooler core and the evaporator; a heater core side heat medium circulation flow path that circulates a heat medium between the heater core and the condenser; an external heat exchanger that exchanges heat between the heat medium introduced from the cooler core side heat medium circulation flow path or the heater core side heat medium circulation flow path and outside air; a cooler core side pump that is provided in the cooler core side heat medium circulation flow path and circulates the heat medium; a heater core side pump that is provided in the heater core side heat medium circulation flow path and circulates the heat medium; and a cooler core side flow adjustment valve that adjusts the flow rate of the heat medium flowing through the cooler core. an external heat exchanger side flow regulation valve that regulates the flow rate of the heat medium flowing through the heater core; and a control unit that controls the compressor, the cooler core side pump, the heater core side pump, the cooler core side flow regulation valve, the heater core side flow regulation valve, and the external heat exchanger side flow regulation valve to perform dehumidifying heating or dehumidifying cooling, wherein the control unit controls the flow rates of the cooler core side pump and the heater core side pump, and the openings of the cooler core side flow regulation valve, the heater core side flow regulation valve, and the external heat exchanger side flow regulation valve so that the flow rates of the heat medium flowing through the cooler core and the heat medium flowing through the heater core do not fall below a predetermined value and reach a target value.

2. The vehicle air conditioning system of claim 1, wherein the control unit controls the temperature of either the heat medium that has undergone heat exchange in the condenser or the heat medium that has undergone heat exchange in the evaporator to reach a target value by controlling the rotation speed of the compressor, and controls the heat exchange amount of the external heat exchanger to reach a target value by controlling the temperature of the other heat medium that has undergone heat exchange in the condenser or the heat medium that has undergone heat exchange in the evaporator.

3. The vehicle air conditioning system according to claim 2, wherein the control unit controls the external heat exchanger side flow adjustment valve to increase its opening when the heat load is greater than a predetermined value.

4. The vehicle air conditioning system according to claim 1, wherein the control unit causes a portion of the heat medium flowing through the heater core side heat medium circulation flow passage to flow into the cooler core.

5. A vehicle air conditioning system as described in claim 1, wherein the control unit supplies a portion of the heat medium flowing out of the heater core to the cooler core side heat medium circulation flow path when the heat medium flows from the heater core side heat medium circulation flow path to the external heat exchanger to perform defrosting operation.

6. A vehicle air conditioning system as described in claim 5, wherein the control unit, after the defrosting operation is completed, causes the heat medium to flow from the cooler core side heat medium circulation flow path to the external heat exchanger at a temperature of 0°C or higher, and supplies a portion of the heat medium flowing out from the heater core to the cooler core side heat medium circulation flow path.

7. A vehicle air conditioning system as described in claim 1, wherein the control unit causes a portion of the heat medium flowing through the cooler core side heat medium circulation flow path to flow into the heater core when the heat medium from the heater core side heat medium circulation flow path is supplied to the external heat exchanger.

8. The vehicle air conditioning system according to claim 1, wherein a bypass passage through which the heat medium flows is provided between the cooler core side heat medium circulation passage and the heater core side heat medium circulation passage.

9. A refrigeration cycle having a compressor that compresses a refrigerant, a condenser that condenses the refrigerant compressed by the compressor, an expansion valve that expands the refrigerant condensed by the condenser, and an evaporator that evaporates the refrigerant expanded by the expansion valve; a cooler core that cools air to be introduced into a passenger compartment; a heater core that heats the air to be introduced into the passenger compartment; a cooler core side heat medium circulation flow path that circulates a heat medium between the cooler core and the evaporator; a heater core side heat medium circulation flow path that circulates a heat medium between the heater core and the condenser; an external heat exchanger that exchanges heat between the heat medium introduced from the cooler core side heat medium circulation flow path or the heater core side heat medium circulation flow path and outside air; a cooler core side pump that is provided in the cooler core side heat medium circulation flow path and circulates the heat medium; a heater core side pump that is provided in the heater core side heat medium circulation flow path and circulates the heat medium; and a cooler core side flow adjustment valve that adjusts the flow rate of the heat medium flowing through the cooler core. A control method for a vehicle air conditioning system comprising: a heater core side flow regulation valve that regulates the flow rate of the heat medium flowing through the heater core; and an external heat exchanger side flow regulation valve that regulates the flow rate of the heat medium flowing through the external heat exchanger, wherein the control method controls the flow rates of the cooler core side pump and the heater core side pump, as well as the openings of the cooler core side flow regulation valve, the heater core side flow regulation valve, and the external heat exchanger side flow regulation valve, so that the flow rates of the heat medium flowing through the cooler core and the heat medium flowing through the heater core do not fall below a predetermined value and reach target values.

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