Vehicle air conditioning system

Abstract

To achieve an air conditioner for a vehicle which restrains temperature from being suddenly decreased while utilizing a heating system effectively by switching a circuit through which a heat medium circulates on the basis of temperature of the heat medium circulating through a first circuit when switching from HV to EV travel.SOLUTION: An air conditioner for a vehicle is an air conditioner of a hybrid vehicle and comprises: a heating system which blows out air of which temperature is raised by passing through a heater core 28 of a circulation path through which a heat medium circulates, into a cabin; and a control part 56. The circulation path includes a first circuit through which the heat medium circulates with an engine 36 used as a heat source and a second circuit though which the heat medium circulates with a heater 32 used as the heat source. The heating system includes a switching valve 38 which is disposed in the circulation path and switches circulation of the heat medium between the first circuit and the second circuit. The control part 56 controls the switching valve 38 on the basis of temperature of the heat medium which circulates through the first circuit when switching from HV to EV travel.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a vehicle air conditioner, and more particularly to an air conditioner mounted on a hybrid vehicle.

Background Art

[0002] Conventionally, an air conditioner has been used to control the heating of a vehicle. In a hybrid vehicle that selectively applies a driving mode in which an engine is driven (hereinafter, appropriately referred to as "HV driving") and a driving mode in which the engine is stopped (hereinafter, appropriately referred to as "EV driving"), a vehicle air conditioner adapted to the characteristics of the vehicle has been proposed.

[0003] For example, Patent Document 1 discloses a hybrid vehicle that controls an air conditioning facility in which a mode of performing heating using electric power stored in a power storage device and a mode of performing heating using an internal combustion engine as a heat source can be selectively implemented. The air conditioning facility is controlled to preferentially implement a mode of performing heating using the engine as a heat source during HV driving. With such a configuration, it is said that power consumption can be suppressed as compared with the case of uniformly performing heating using electric power stored in the power storage device regardless of whether it is HV driving or EV driving. Further, during EV driving in which the internal combustion engine is stopped and the vehicle is driven by the power of the electric motor, the heating capacity can be ensured without operating the internal combustion engine, so that it is said that heating control suitable for a hybrid vehicle can be performed.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] By the way, in hybrid vehicles, which use waste heat from the engine to heat the cabin during HV driving and a heater during EV driving, the engine is used as the heat source for the heating system during HV driving, so the water temperature circulating in the heating system is high. Therefore, in such heating systems, outside air is taken in and mixed with air heated by the engine's coolant to achieve a comfortable temperature for the occupants, and this mixed air is then blown into the cabin. Specifically, the degree to which the outside air and the air heated by the coolant are mixed is adjusted so that the temperature of the air blown into the cabin reaches the set temperature. To make this adjustment, the opening of the air mix damper is controlled, and generally, during HV driving when the water temperature is sufficiently high, the opening of the air mix damper is widened.

[0006] As described above, when the air mix damper is wide open, the water temperature circulating in the heating system tends to decrease. Also, generally, when switching from HV driving to EV driving, the circulation path in which the heat transfer medium circulates using the engine as a heat source is interrupted, and the circulation path switches to one that uses the heater as a heat source. In other words, when switching from HV driving to EV driving, in addition to the decrease in water temperature due to the opening of the air mix damper, a decrease in water temperature also occurs due to the use of the heater, which has a smaller heat capacity compared to the engine, as a heat source. As a result, the heating temperature may drop sharply.

[0007] Therefore, this specification provides for a vehicle air conditioning system that suppresses a rapid drop in heating temperature when switching from HV driving to EV driving. [Means for solving the problem]

[0008] The vehicle air conditioning system disclosed herein is a vehicle air conditioning system for a hybrid vehicle that heats the cabin using waste heat from the engine during HV driving and using a heater during EV driving, and comprises a heating system that blows air that has been heated by passing through a heater core in a circulation path through which a heat transfer medium circulates into the cabin, and a control unit, wherein the circulation path has a first circuit in which the heat transfer medium circulates with the engine as the heat source, and a second circuit in which the heat transfer medium circulates with the heater as the heat source, and the heating system has a switching valve arranged in the circulation path that switches the circulation of the heat transfer medium between the first circuit and the second circuit, and the control unit controls the switching valve based on the temperature of the heat transfer medium circulating in the first circuit when the vehicle switches from HV driving to EV driving.

[0009] With the above configuration, when switching from HV driving to EV driving, the circuit to which the heat transfer medium circulates can be switched based on the temperature of the heat transfer medium circulating in the first circuit. This allows for effective use of the heating system while suppressing a rapid drop in heating temperature.

[0010] Furthermore, the vehicle air conditioning system is characterized in that the control unit uses a threshold value obtained by adding a predetermined value to the target temperature of the heat transfer medium circulating in the heater core, and controls the switching valve to circulate the heat transfer medium in the first circuit when the temperature of the heat transfer medium circulating in the first circuit is equal to or greater than the threshold value, and controls the switching valve to circulate the heat transfer medium in the second circuit when the temperature of the heat transfer medium circulating in the first circuit is lower than the threshold value.

[0011] With the above configuration, the circuit through which the heat transfer medium circulates can be switched based on a comparison between the temperature of the heat transfer medium circulating in the first circuit and a threshold value obtained by adding a predetermined value to the target temperature. This allows for the effective utilization of engine waste heat that is hotter than the threshold value. [Effects of the Invention]

[0012] According to the vehicle air conditioning system disclosed herein, when switching from HV driving to EV driving, instead of uniformly switching the circuit through which the heat transfer medium circulates from the first circuit to the second circuit, the circuit through which the heat transfer medium circulates can be switched based on the temperature of the heat transfer medium circulating in the first circuit. This makes it possible to effectively utilize the heating system while suppressing a rapid drop in heating temperature. [Brief explanation of the drawing]

[0013] [Figure 1] This diagram schematically shows an example of the configuration of a vehicle air conditioning system. [Figure 2] This is a flowchart illustrating the processing procedure executed by the control unit. [Modes for carrying out the invention]

[0014] The vehicle air conditioning system will be described below with reference to the drawings. However, the present invention is not limited to the embodiments described herein.

[0015] Figure 1 is a schematic diagram illustrating an example of the configuration of a vehicle air conditioning system. In Figure 1, "Up" indicates the area above the vehicle. The vehicle air conditioning system described with reference to Figure 1 is installed in known hybrid vehicles that use waste heat from the engine during HV driving and a heater during EV driving to heat the cabin. The vehicle air conditioning system in this example comprises a heating system and a control unit. The control unit controls a switching valve located in the circulation path to adjust the temperature of the air blown into the cabin. Further details about the heating system, control unit, and switching valve will be described later.

[0016] In this example, the hybrid vehicle equipped with a vehicle air conditioning system is provided with a ventilation duct 10. As shown in Figure 1, the ventilation duct 10 has an interior air intake 12 and an exterior air intake 14. The interior air intake 12 takes in air from inside the vehicle, drawing in interior air from openings provided at the front and rear of the vehicle interior. The exterior air intake 14 takes in outside air from outside the vehicle, usually drawing in outside air from an opening provided at the front of the vehicle.

[0017] A blower 16 is positioned inside the inner air intake 12 and outer air intake 14 of the ventilation duct 10. The blower 16 has a fan 20 driven by a motor 18, and the rotation of the fan 20 draws in air (i.e., inner and outer air) from the inner air intake 12 and outer air intake 14. A damper 22 is positioned inside the inner air intake 12 and outer air intake 14. The damper 22 adjusts the opening degree of the inner air intake 12 and outer air intake 14, and the position of the damper 22 allows adjustment from 100% inner air (0% outer air) to 0% inner air (100% outer air). Note that the blower 16 and damper 22 may be provided separately for inner air and outer air, respectively, and controlled independently.

[0018] An evaporator 24 is located downstream of the blower 16 in the ventilation duct 10. A circulation path (not shown) is formed in the evaporator 24. A heat pump system is constructed by circulating a heat transfer medium through this circulation path.

[0019] On the downstream side of the evaporator 24, an air mix damper 26 is arranged. The air mix damper 26 is movable from an upper closed position to a lower closed position. A heater core 28 is arranged in the lower passage downstream of the air mix damper 26. When the air mix damper 26 is in the lower closed position, 100% of the air flowing in the ventilation duct 10 will bypass the heater core 28. On the other hand, when the air mix damper 26 is in the upper closed position, 100% of the air flowing in the ventilation duct 10 will pass through the heater core 28. In other words, by moving the air mix damper 26 from the upper closed position to the lower closed position, the mixing ratio of the air passing through the heater core 28 and the air not passing through the heater core 28 can be changed.

[0020] A circulation path including a circuit in which water circulates in the EV driving where a water pump (WP) 30 and a heater 32 are connected to the heater core 28 and a circuit in which water circulates in the HV driving where WP 34 and an engine 36 are connected is formed, and a heating system is constituted. Hereinafter, the circuit in which water circulates with the engine 36 as a heat source (that is, the circuit in which WP 34 and the engine 36 are connected) is referred to as the "first circuit". Also, the circuit in which water circulates with the heater 32 as a heat source (that is, the circuit in which WP 30 and the heater 32 are connected) is referred to as the "second circuit". In addition, a switching valve 38 arranged between the first circuit and the second circuit is provided in the circulation path of this heating system. By operating this switching valve 38, it is possible to switch which of the first circuit and the second circuit the water flows through. The operation of the switching valve 38 will be described later.

[0021] Also, in this example, in the circulation path of the heating system, water circulates as a heat medium as described above, and the air that has passed through the heater core 28 and has been heated in temperature is blown into the passenger compartment. The heater 32 is, for example, an electric heater and heats the circulating water. The temperature of the circulating water is measured by a water temperature sensor 40.

[0022] On the downstream side of the heater core 28, three outlets are provided: a foot outlet 42, a passenger outlet 44, and a defrost outlet 46. The foot outlet 42 blows air from within the ventilation duct 10 toward the feet of the driver and passenger in the driver's and front passenger's seats. The passenger outlet 44 blows air toward the upper bodies of the driver and front passenger. And the defrost outlet 46 blows air from the lower part to the upper part inside the windshield.

[0023] A foot damper 48 is provided at the foot outlet 42, a passenger damper 50 is provided at the passenger outlet 44, and a defrost damper 52 is provided at the defrost outlet 46, respectively, and the blowing of air from the ventilation duct 10 can be controlled. Here, in this example, the foot damper 48, the passenger damper 50, and the defrost damper 52 are configured such that their opening and closing operations are controlled by the drive unit 54.

[0024] The control unit 56 controls the opening and closing of the damper 22 and the air mix damper 26, the processing performed by the drive unit 54 (i.e., the opening and closing of the three outlet dampers 48, 50, 52 on the blowing side), the heating of the heater 32, etc. The control unit 56 is supplied with the temperatures from an inside air sensor 58 provided near the inside air intake 12, an outside air sensor 60 provided near the outside air intake 14, and a water temperature sensor 40 provided in the circulation path to the heater core 28. Also, a solar sensor 62 that measures the intensity of the outside light incident on the vehicle interior is provided near the windshield glass, and this detected value is also supplied to the control unit 56. Furthermore, in the hybrid vehicle of this example equipped with the vehicle air conditioner, a control panel 64 for receiving the input of the occupant regarding the temperature setting in the vehicle interior, the switching between the outside air mode, the inside air mode, and the inside / outside air mixing mode, the selection of the outlet, etc. is provided, and an operation signal from the control panel 64 is supplied to the control unit 56.

[0025] Regarding the intake of internal and external air, when the external air intake port 14 is fully closed and the internal air intake port 12 is fully open using the damper 22, it becomes internal air mode (damper 22: dashed line position). When the external air intake port 14 is fully open and the internal air intake port 12 is fully closed using the damper 22, it becomes external air mode (damper 22: sandy ground position). Furthermore, when the damper 22 is positioned between the internal air mode and the external air mode, it becomes internal and external air mixed mode.

[0026] Next, the control of the heating system performed by the control unit 56 will be described. Based on the set temperature, indoor air, outdoor air, and indoor / outdoor air mode settings set on the control panel 64, the selection of the air outlet, and the detection values ​​of the various sensors mentioned above, the control unit 56 controls the damper 22, air mix damper 26, heater 32, etc.

[0027] Furthermore, the control unit 56 calculates the target air outlet temperature based on the cabin temperature, the set cabin temperature, and the detection values ​​of the various sensors mentioned above. The outlet from which the air is blown is determined based on the settings in the control panel 64. Similarly, the airflow volume will be set to the volume specified in the control panel 64, but if the airflow volume is set to automatic, it should be determined according to the required amount of heat for heating the cabin. For example, the higher the target air outlet temperature, the greater the airflow volume can be set.

[0028] Furthermore, the control unit 56 determines the target temperature of the heat transfer medium (i.e., water) circulating in the heater core 28. This target temperature may be determined in correspondence with the target discharge temperature. That is, the control unit 56 may add a predetermined value to the target discharge temperature, taking into consideration the efficiency of heat exchange in the heater core 28 and the heat loss in the ventilation duct 10 leading to the discharge port, and set the target temperature slightly higher than the target discharge temperature. Then, the control unit 56 uses the value obtained by adding a predetermined value to the target temperature as a threshold value, compares the temperature of the heat transfer medium circulating in the first circuit with the threshold value, and controls the switching valve 38. The control of the switching valve 38 performed by the control unit 56 will be further explained below with reference to Figure 2.

[0029] Figure 2 is a flowchart illustrating the processing procedure performed by the control unit. First, the control unit 56 determines whether the hybrid vehicle in this example has transitioned from HV driving to EV driving (S10). If the control unit 56 determines that the vehicle has transitioned from HV driving to EV driving (Yes in S10), it compares the temperature of the heat transfer medium circulating in the first circuit (hereinafter referred to as "heat transfer medium temperature of the first circuit") with a threshold value (S12). On the other hand, if the control unit 56 determines that the vehicle has not transitioned from HV driving to EV driving (No in S10), it does not control the switching valve 38 (S14) and terminates the process. In this example, the heat transfer medium temperature of the first circuit is measured by the water temperature sensor 40, and the control unit 56 accepts the measured temperature. The threshold value is a value obtained by adding a predetermined value to the target temperature, which is determined in accordance with the target discharge temperature based on the detection values ​​of various sensors, and is set in advance by the control unit 56.

[0030] Next, when the control unit 56 determines that the temperature of the heat transfer medium in the first circuit is above a threshold (Yes in S12), it controls the switching valve 38 to circulate the heat transfer medium in the first circuit (S16). In other words, in HV driving, the heating system circulates the heat transfer medium in the first circuit, which uses the engine 36 as a heat source, so the control unit 56 maintains the circulation of the heat transfer medium in the first circuit without changing the operation of the switching valve 38. On the other hand, when the control unit 56 determines that the temperature of the heat transfer medium in the first circuit is below a threshold (No in S12), it controls the switching valve 38 to circulate the heat transfer medium in the second circuit (S18). That is, in order to shut off the circulation of the heat transfer medium in the first circuit, which was used in HV driving, and switch to circulation in the second circuit, the control unit 56 operates the switching valve 38, closing the valve on the first circuit side and opening the valve on the second circuit side.

[0031] Furthermore, when the vehicle transitions from HV driving to EV driving, the water temperature gradually decreases due to the stopping of the engine 36, so there is a time when the temperature of the heat transfer medium in the first circuit falls below the threshold. Therefore, even if the control unit 56 determines in step S12 that the temperature of the heat transfer medium in the first circuit is above the threshold and maintains the circulation of the heat transfer medium in the first circuit in step S16, the comparison between the temperature of the heat transfer medium in the first circuit and the threshold is repeatedly performed thereafter.

[0032] Thus, when the heat transfer medium temperature in the first circuit is above a threshold, the circulation of the heat transfer medium in the first circuit is maintained, allowing the high-temperature first circuit to be utilized. This allows for more efficient use of the heating system compared to a uniform switch from the first circuit to the second circuit when switching from HV driving to EV driving. Subsequently, when the heat transfer medium temperature in the first circuit drops to a certain temperature, the system switches to the second circuit, thus achieving both effective use of the heating system and suppression of a rapid drop in heating temperature.

[0033] It should be noted that the above description is merely an example, and in the vehicle air conditioning system disclosed herein, the control unit may control the switching valve based on the temperature of the heat transfer medium circulating in the first circuit when switching from HV driving to EV driving. Therefore, other components of the vehicle air conditioning system may be modified as appropriate. [Explanation of Symbols]

[0034] 28 Heater core, 30, 34 Water pump, 32 Heater, 36 Engine, 38 Switching valve, 56 Control unit.

Claims

1. A vehicle air conditioning system for a hybrid vehicle that uses waste heat from the engine during HV driving and a heater during EV driving to heat the interior of the vehicle, A heating system that blows air that has been heated by passing through a heater core in a circulation path through which a heat transfer medium circulates into the vehicle interior, Control unit and Equipped with, The circulation path comprises a first circuit in which the heat transfer medium circulates using the engine as a heat source, and a second circuit in which the heat transfer medium circulates using the heater as a heat source. The heating system includes a switching valve located in the circulation path, which switches the circulation of the heat transfer medium between the first circuit and the second circuit. The control unit controls the switching valve based on the temperature of the heat transfer medium circulating in the first circuit when switching from HV driving to EV driving. A vehicle air conditioning system characterized by the following features.

2. The control unit, A threshold value is used, which is obtained by adding a predetermined value to the target temperature of the heat transfer medium circulating in the heater core. When the temperature of the heat transfer medium circulating in the first circuit is equal to or greater than the threshold, the switching valve is controlled to circulate the heat transfer medium in the first circuit. When the temperature of the heat transfer medium circulating in the first circuit is lower than the threshold, the switching valve is controlled to circulate the heat transfer medium in the second circuit. The vehicle air conditioning system according to feature 1.

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