JP2024126227A - Vehicle air conditioning system - Google Patents

Abstract

[Problem] To realize a vehicle air conditioner that effectively utilizes the heating system while suppressing a sudden drop in heating temperature by switching the circuit through which the heat medium circulates based on the temperature of the heat medium circulating in the first circuit when switching from HV to EV driving. [Solution] The vehicle air conditioner is an air conditioner for a hybrid vehicle, and includes a heating system that blows air into the vehicle cabin, the air having a temperature increased by passing through a heater core 28 in a circulation path through which the heat medium circulates, and a control unit 56, the circulation path having a first circuit through which the heat medium circulates using an engine 36 as a heat source, and a second circuit through which the heat medium circulates using a heater 32 as a heat source, the heating system having a switching valve 38 disposed in the circulation path for switching the circulation of the heat medium between the first circuit and the second circuit, and the control unit 56 controls the switching valve 38 based on the temperature of the heat medium circulating in the first circuit when switching from HV to EV driving. [Selected Figure] Figure 1

Description

The present invention relates to an air conditioner for a vehicle, and in particular to an air conditioner installed in a hybrid vehicle.

Conventionally, air conditioners have been used to control the heating of vehicles. For hybrid vehicles that selectively use a driving mode in which the engine is driven (hereinafter referred to as "HV driving") and a driving mode in which the engine is stopped (hereinafter referred to as "EV driving"), vehicle air conditioners tailored to the characteristics of the vehicle have been proposed.

For example, Patent Document 1 discloses a hybrid vehicle that controls an air conditioning system that can selectively implement a heating mode using electricity stored in an electricity storage device and a heating mode using an internal combustion engine as a heat source. The air conditioning system is controlled to prioritize a heating mode using the engine as a heat source during HV driving. This configuration is said to reduce power consumption compared to a case where heating is performed uniformly using electricity stored in an electricity storage device regardless of whether the vehicle is HV driving or EV driving. Also, during EV driving, in which the internal combustion engine is stopped and the vehicle runs on power from an electric motor, heating capacity can be secured without operating the internal combustion engine, so heating control suitable for hybrid vehicles can be achieved.

JP 2015-077852 A

In hybrid vehicles, which use engine waste heat during HV driving and a heater during EV driving to heat the passenger compartment, the engine is used as a heat source to use the heating system during HV driving, so the temperature of the water circulating through the heating system is high. For this reason, such heating systems are set up to take in outside air, mix it with air heated by coolant using the engine as a heat source, and blow the mixed air into the passenger compartment to provide a comfortable temperature for the occupants. Specifically, the degree of mixing of the outside air and the air heated by the coolant is adjusted so that the temperature of the air blown into the passenger compartment is a set temperature. To make this adjustment, the opening of the air mix damper is controlled, and generally, the opening of the air mix damper is widened during HV driving when the water temperature is sufficiently high.

As mentioned above, when the air mix damper is open widely, the temperature of the water circulating through the heating system is likely to drop. In addition, when switching from HV driving to EV driving, the circulation path through which the heat medium circulates using the engine as the heat source is generally cut off and switched to a circulation path that uses the heater as the heat source. In other words, when switching from HV driving to EV driving, in addition to the drop in water temperature caused by the opening of the air mix damper, a drop in water temperature also occurs due to the use of a heater, which has a smaller thermal capacity than the engine, as a heat source. As a result, the heating temperature may drop suddenly.

Therefore, this specification provides a vehicle air conditioning system that suppresses a sudden drop in heating temperature when switching from HV driving to EV driving.

The vehicle air conditioner disclosed in this specification is a vehicle air conditioner for a hybrid vehicle that uses engine waste heat during HV driving and a heater during EV driving to heat the vehicle interior, and is equipped with a heating system that blows air into the vehicle interior whose temperature has increased by passing through a heater core in a circulation path through which a heat medium circulates, and a control unit, the circulation path having a first circuit through which the heat medium circulates using the engine as a heat source and a second circuit through which the heat medium circulates using the heater as a heat source, the heating system having a switching valve disposed in the circulation path that switches the circulation of the heat medium between the first circuit and the second circuit, and the control unit controls the switching valve based on the temperature of the heat medium circulating in the first circuit when switching from the HV driving to the EV driving.

According to the above configuration, when switching from HV driving to EV driving, the circuit through which the heat medium circulates can be switched based on the temperature of the heat medium circulating in the first circuit, so that a sudden drop in heating temperature can be suppressed while effectively utilizing the heating system.

The vehicle air conditioning system is also characterized in that the control unit uses a value obtained by adding a predetermined value to the target temperature of the heat medium circulating through the heater core as a threshold value, and when the temperature of the heat medium circulating through the first circuit is equal to or higher than the threshold value, controls the switching valve to circulate the heat medium through the first circuit, and when the temperature of the heat medium circulating through the first circuit is lower than the threshold value, controls the switching valve to circulate the heat medium through the second circuit.

With the above configuration, the circuit through which the heat medium circulates can be switched based on a comparison between the temperature of the heat medium circulating in the first circuit and a threshold value obtained by adding a predetermined value to the target temperature, so that engine waste heat that is hotter than the threshold value can be effectively utilized.

According to the vehicle air conditioning device disclosed in this specification, when switching from HV driving to EV driving, the circuit through which the heat medium circulates can be switched based on the temperature of the heat medium circulating in the first circuit, rather than being switched uniformly from the first circuit to the second circuit, so that a sudden drop in heating temperature can be suppressed while effectively utilizing the heating system.

1 is a diagram illustrating an example of a configuration of a vehicle air conditioner; 10 is a flowchart illustrating a processing procedure executed by a control unit.

The vehicle air conditioner will now be described with reference to the drawings. Note that the present invention is not limited to the embodiments described herein.

Figure 1 is a schematic diagram showing an example of the configuration of a vehicle air conditioner. In Figure 1, "Up" indicates the upper side of the vehicle. The vehicle air conditioner described with reference to Figure 1 is installed in a known hybrid vehicle that uses engine waste heat during HV driving and a heater during EV driving to heat the vehicle interior. The vehicle air conditioner of this example includes a heating system and a control unit, and the control unit controls a switching valve arranged in the circulation path to adjust the temperature of the air blown into the vehicle interior. The heating system, control unit, and switching valve will be described in detail later.

The hybrid vehicle in this example equipped with the vehicle air conditioning system has an air duct 10. As shown in FIG. 1, the air duct 10 has an inside air intake 12 and an outside air intake 14. The inside air intake 12 takes in air from within the vehicle cabin, and takes in inside air from openings provided at the front and rear of the vehicle cabin. The outside air intake 14 takes in outside air from outside the vehicle, and usually takes in outside air from an opening provided at the front of the vehicle.

A blower 16 is disposed inside the inside air intake 12 and the outside air intake 14 of the ventilation duct 10. The blower 16 has a fan 20 driven by a motor 18, and air (i.e., inside air and outside air) is taken in from the inside air intake 12 and the outside air intake 14 by the rotation of the fan 20. A damper 22 is disposed inside the inside air intake 12 and the outside air intake 14. The damper 22 adjusts the opening degree of the inside air intake 12 and the outside air intake 14, and can be adjusted from 100% inside air (0% outside air) to 0% inside air (100% outside air) depending on the position of the damper 22. The blower 16 and the damper 22 may be provided separately for inside air and outside air, so that they can be controlled independently.

An evaporator 24 is disposed 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 formed by circulating a heat medium through this circulation path.

An air mix damper 26 is disposed downstream of the evaporator 24. The air mix damper 26 is movable from an upper closed position to a lower closed position. A heater core 28 is disposed 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 bypasses 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 passes through the heater core 28. In other words, the air mix damper 26 can change the mixture ratio between the air that passes through the heater core 28 and the air that does not pass through the heater core 28 by moving from the upper closed position to the lower closed position.

The heater core 28 is provided with a circulation path including a circuit in which water is circulated during EV driving, in which the water pump (WP) 30 and the heater 32 are connected, and a circuit in which water is circulated during HV driving, in which the WP 34 and the engine 36 are connected, to form a heating system. Hereinafter, the circuit in which water is circulated using the engine 36 as a heat source (i.e., the circuit in which the WP 34 and the engine 36 are connected) will be referred to as the "first circuit." Also, the circuit in which water is circulated using the heater 32 as a heat source (i.e., the circuit in which the WP 30 and the heater 32 are connected) will be referred to as the "second circuit." The circulation path of this heating system is provided with a switching valve 38 disposed between the first circuit and the second circuit. By operating this switching valve 38, it is possible to switch between the first circuit and the second circuit through which water flows. The operation of the switching valve 38 will be described later.

In this example, water is circulated as a heat medium in the circulation path of the heating system as described above, and air whose temperature has increased by passing through the heater core 28 is blown into the vehicle cabin. 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.

Three outlets are provided downstream of the heater core 28: a foot-side outlet 42, a passenger-side outlet 44, and a defrost-side outlet 46. The foot-side outlet 42 blows air from inside the ventilation duct 10 toward the feet of the driver's and passenger's seats. The passenger-side outlet 44 blows air toward the upper bodies of the driver's and passenger's seats. The defrost-side outlet 46 blows air from the bottom to the top of the inside of the windshield.

A foot-side damper 48 is provided at the foot-side outlet 42, an occupant-side damper 50 at the occupant-side outlet 44, and a defrost-side damper 52 at the defrost-side outlet 46, and this allows control of the air blown out from the ventilation duct 10. Here, in this example, the opening and closing operations of the foot-side damper 48, the occupant-side damper 50, and the defrost-side damper 52 are controlled by a drive unit 54.

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 dampers 48, 50, 52 on the blowing side), the heating of the heater 32, etc. The control unit 56 is supplied with 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. In addition, a solar radiation sensor 62 that measures the intensity of outside light entering the passenger compartment is provided near the windshield glass, and this detection value is also supplied to the control unit 56. Furthermore, the hybrid vehicle of this example equipped with a vehicle air conditioning system is provided with a control panel 64 that accepts inputs from the occupant regarding the temperature setting in the passenger compartment, switching between outside air mode, inside air mode, and inside/outside air mixed mode, and selection of the air outlet, etc., and an operation signal from the control panel 64 is supplied to the control unit 56.

Regarding the intake of inside and outside air, when the damper 22 fully closes the outside air intake 14 and fully opens the inside air intake 12, it is the inside air mode (damper 22: dashed line position), and when the damper 22 fully opens the outside air intake 14 and fully closes the inside air intake 12, it is the outside air mode (damper 22: sandy position). And when the damper 22 is positioned between the inside air mode and the outside air mode, it is the inside/outside air mixed mode.

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

The control unit 56 also calculates the target blowing temperature based on the vehicle interior temperature, the set vehicle interior temperature, the detection values of the various sensors described above, and the like. Which outlet to blow air from is determined based on the settings on the control panel 64. The air volume will also be the air volume set on the control panel 64, but if the air volume is set automatically, it can be determined according to the required heat amount for heating the vehicle interior. For example, the higher the target blowing temperature, the larger the air volume can be set.

The control unit 56 also determines a target temperature of the heat medium (i.e., water) circulating through the heater core 28. This target temperature may be determined in accordance with the target outlet temperature. That is, the control unit 56 may add a predetermined value to the target outlet temperature, taking into account the efficiency of heat exchange in the heater core 28 and the heat loss in the ventilation duct 10 that passes to the outlet, and set the target temperature slightly higher than the target outlet temperature. The control unit 56 then uses the value obtained by adding the predetermined value to the target temperature as a threshold value, compares the temperature of the heat medium circulating through 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 described below with reference to FIG. 2.

2 is a flowchart explaining the processing procedure executed by the control unit. First, the control unit 56 judges whether or not the hybrid vehicle in this example has transitioned from HV driving to EV driving (S10). When the control unit 56 judges that the hybrid vehicle has transitioned from HV driving to EV driving (Yes in S10), it compares the temperature of the heat medium circulating in the first circuit (hereinafter referred to as the "heat medium temperature of the first circuit") with the threshold value (S12). On the other hand, when the control unit 56 judges that the hybrid vehicle has not transitioned from HV driving to EV driving (No in S10), it does not control the switching valve 38 (S14) and ends the processing. In this example, the heat 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 a target temperature determined in accordance with a target blowing temperature based on detection values of various sensors, and is set in advance by the control unit 56.

Next, when the control unit 56 determines that the heat medium temperature in the first circuit is equal to or higher than the threshold value (Yes in S12), it controls the switching valve 38 to circulate the heat medium in the first circuit (S16). In other words, during HV driving, the heating system circulates the heat medium in the first circuit using the engine 36 as a heat source, so the control unit 56 maintains the circulation of the heat 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 heat medium temperature in the first circuit is lower than the threshold value (No in S12), it controls the switching valve 38 to circulate the heat medium in the second circuit (S18). That is, in order to shut off the circulation of the heat medium in the first circuit used during HV driving and switch to circulation in the second circuit, the control unit 56 operates the switching valve 38 to close the valve on the first circuit side and open the valve on the second circuit side.

When transitioning from HV driving to EV driving occurs, the water temperature gradually drops due to the engine 36 being stopped, and there is a time when the heat medium temperature in the first circuit falls below the threshold value. Therefore, even if the control unit 56 determines in step S12 that the heat medium temperature in the first circuit is equal to or higher than the threshold value and maintains the circulation of the heat medium in the first circuit in step S16, it continues to repeatedly compare the heat medium temperature in the first circuit with the threshold value.

In this way, when the heat medium temperature in the first circuit is equal to or higher than the threshold value, the circulation of the heat medium in the first circuit can be maintained, making it possible to utilize the first circuit, which is at a high temperature, and therefore the heating system can be used more efficiently than if the first circuit were switched to the second circuit uniformly when switching from HV driving to EV driving. Then, when the heat medium temperature in the first circuit drops to a certain temperature, the circuit is switched to the second circuit, making it possible to achieve both effective use of the heating system and prevention of a sudden drop in heating temperature.

Note that the above description is merely an example, and the vehicle air conditioning device disclosed in this specification may be configured such that, when switching from HV driving to EV driving, the control unit controls the switching valve based on the temperature of the heat medium circulating through the first circuit. Therefore, other configurations of the vehicle air conditioning device may be changed as appropriate.

28 heater core, 30, 34 water pump, 32 heater, 36 engine, 38 switching valve, 56 control unit.

Claims (2)

A vehicle air conditioning device for a hybrid vehicle that uses waste heat from an engine during HV driving and uses a heater during EV driving to heat the vehicle interior,
a heating system that blows air whose temperature has been increased by passing through a heater core in a circulation path in which a heat medium circulates into the vehicle interior;
A control unit;
Equipped with
the circulation path includes a first circuit through which the heat medium circulates using the engine as a heat source, and a second circuit through which the heat medium circulates using the heater as a heat source,
The heating system includes a switching valve disposed in the circulation path, the switching valve switching the circulation of the heat medium between the first circuit and the second circuit,
The control unit controls the switching valve based on a temperature of the heat medium circulating through the first circuit when the HV traveling is switched to the EV traveling.
1. A vehicle air conditioning system comprising: The control unit is
A value obtained by adding a predetermined value to the target temperature of the heat medium circulating through the heater core is used as a threshold value,
When a temperature of the heat medium circulating through the first circuit is equal to or higher than the threshold value, the switching valve is controlled to circulate the heat medium through the first circuit;
When a temperature of the heat medium circulating through the first circuit is lower than the threshold value, the switching valve is controlled to circulate the heat medium through the second circuit.
2. The vehicle air conditioning system according to claim 1.

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