Patent Publication Number: US-2023148249-A1

Title: Vehicle air conditioner control system and non-transitory recording medium storing vehicle air conditioner control program

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application claims priority to Japanese Patent Application No. 2021-182422, filed on Nov. 9, 2021, which is incorporated herein by reference in its entirety including the specification, claims, drawings, and abstract. 
     TECHNICAL FIELD 
     The specification discloses a vehicle air conditioner control system installed on a vehicle capable of autonomous driving, and a non-transitory recording medium storing a vehicle air conditioner control program to be executed by the system. 
     BACKGROUND 
     JP 2017-210019 A, for example, discloses an air conditioner control process performed during autonomous driving of a vehicle. The control process controls an air conditioner to place a higher priority on occupants&#39; comfort than on occupants&#39; visibility during autonomous driving as compared to when autonomous driving is not performed. For example, during autonomous driving, keeping moisture within the vehicle cabin takes precedence over defogging of the windshield (windshield glass). 
     In response to the vehicle passing a point located a predetermined distance before a transition point from the autonomous driving mode to the manual driving mode, whether windshield fogging occurs is detected. Then, in response to detection of windshield fogging, a defroster is actuated. Actuation of the defroster at a point before the transition point enables an increase in the visibility of a vehicle occupant (especially a driver) to outside the vehicle before transition to the manual driving mode. 
     JP H8-244448 A, for example, further discloses a vehicle air conditioner controller. The air conditioner includes a compressor that compresses a refrigerant and is driven with electric power from an internal combustion engine or an on-vehicle battery. 
     In the former case, the output of the internal combustion engine is partially assigned to driving of the compressor, with the remaining output being assigned to driving power of the vehicle. In the latter case, as the electric power from the on-vehicle battery is supplied to the rotary electric machine in a vehicle including the rotary electric machine serving as a drive source, the power of the on-vehicle battery is allocated to the compressor and the rotary electric machine. 
     In response to a large driving power required for a vehicle, such as at the time of sudden acceleration or going uphill, air conditioner power cutting control is performed for temporarily reducing, or typically stopping, the output of the compressor to thereby secure the driving performance of the vehicle. Based on an autonomous mode selected for operation setting of the air conditioner, for example, the air conditioner controller performs the air conditioner power cutting control in accordance with the driving power required for the vehicle. 
     The present specification discloses a vehicle air conditioner control system that enables securing of a windshield glass defogging function at the time of switching from autonomous driving to manual driving, and a non-transitory recording medium storing a vehicle air conditioner control program. 
     SUMMARY 
     A vehicle air conditioner control system disclosed in the specification includes an air conditioner, an air conditioner controller, and an autonomous driving controller. The air conditioner includes a compressor. The compressor is configured to contend with a driving wheel for torque of an internal combustion engine or to contend with a rotary electric machine that is a vehicle drive source for battery power. The air conditioner controller is configured to switch operation control of the air conditioner between manual control and autonomous control. The autonomous driving controller is configured to perform autonomous driving control of the vehicle. The air conditioner controller is further configured to perform air conditioner power cutting control to regulate driving of the compressor in accordance with required vehicle driving force, during execution of the autonomous control. In a driving switching preparing section of a road wherein autonomous driving performed by the autonomous driving controller is to be switched to manual driving performed by a driver, the air conditioner controller is configured to prohibit performance of the air conditioner power cutting control. 
     The above configuration secures a defogging function for a windshield glass while the vehicle is travelling in the driving switching preparing section. 
     In the above configuration, the air conditioner controller may include a fogging determining unit configured to determine whether fogging occurs on a windshield glass. In this case, in response to determining occurrence of fogging on the windshield glass by the fogging determining unit in the driving switching preparing section, the air conditioner controller prohibits execution of the air conditioner power cutting control. 
     The above configuration enables performance of the air conditioner power cutting control in the absence of windshield glass fogging. Therefore, to travel the driving switching preparing section including an uphill, the air conditioner power cutting control is performed to enable securing of the vehicle driving force. 
     In the above configuration, the autonomous driving controller may continue the autonomous driving control in the driving switching preparing section until the fogging determining unit determines elimination of fogging on the windshield glass. This configuration enables switching from autonomous driving to manual driving after securing the driver&#39;s field of view. 
     The specification further discloses a non-transitory recording medium storing a vehicle air conditioner control program. This program causes a computer to be used with an air conditioner and an autonomous driving controller to function as an air conditioner controller. The air conditioner includes a compressor configured to contend with a driving wheel for torque of an internal combustion engine or to contend with a rotary electric machine that is a vehicle drive source for battery power. The autonomous driving controller is configured to perform autonomous driving control of a vehicle. This program enables the air conditioner controller to switch operation control of the air conditioner between manual control and autonomous control. This program further enables the air conditioner controller to perform air conditioner power cutting control to regulate driving of the compressor in accordance with required vehicle driving force during execution of the autonomous control. This program further allows the autonomous driving controller to prohibit performance of the air conditioner power cutting control in a driving switching preparing section of a road wherein autonomous driving performed by the autonomous driving controller is switched to manual driving performed by a driver. 
     In the above configuration, the air conditioner controller may include a fogging determining unit configured to determine whether fogging occurs on a windshield glass. In this case, in response to determining occurrence of fogging on the windshield glass by the fogging determining unit in the driving switching preparing section, the air conditioner controller prohibits performing of the air conditioner power cutting control. 
     In the above configuration, the autonomous driving controller may continue the autonomous driving control in the driving switching preparing section until the fogging determining unit determines elimination of fogging on the windshield glass. 
     The vehicle air conditioner control system according to the present specification enables securing of the defogging function for the windshield glass at the time of switching from autonomous driving to manual driving. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       Embodiment(s) of the present disclosure will be described based on the following figures, wherein: 
         FIG.  1    illustrates a configuration of a vehicle in which a vehicle air conditioner control system according to an embodiment is mounted; 
         FIG.  2    illustrates a hardware configuration of an air conditioner ECU; 
         FIG.  3    is a diagram illustrating devices shown in  FIG.  1    related to autonomous driving control; 
         FIG.  4    illustrates an autonomous driving section, a manual driving section, and a driving switching preparing section; 
         FIG.  5    illustrates switches within the vehicle cabin; 
         FIG.  6    illustrates sensors disposed in a front of the vehicle; 
         FIG.  7    illustrates an example of a mounted camera unit; 
         FIG.  8    illustrates an air conditioner; 
         FIG.  9    illustrates operation of the air conditioner during heating operation; 
         FIG.  10    illustrates operation of the air conditioner during a cooling mode; 
         FIG.  11    illustrates operation of the air conditioner during a dehumidifying mode; 
         FIG.  12    illustrates a flow of air conditioner power reduction setting; 
         FIG.  13    illustrates a flow of air conditioner power reduction setting according to a first further example; and 
         FIG.  14    illustrates a flow of air conditioner power reduction setting according to a second further example. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Entire Configuration 
       FIG.  1    illustrates the entire configuration of a vehicle  100 , including a vehicle air conditioner control system according to an embodiment.  FIG.  1    mainly illustrates devices required for autonomous driving control and air conditioning control of the vehicle  100 , and does not illustrate devices not significantly related to these controls. 
     The vehicle  100  may be a battery electric vehicle (BEV) including a rotary electric machine  11 , for example, serving as a driving source. However, the vehicle  100  is not limited to a battery electric vehicle (BEV), and may be any vehicle that allows autonomous driving control and also allow contention for torque or electric power between driving of a compressor  33  of an air conditioner  25  and driving of the vehicle, and may be a hybrid electric vehicle (HEV) or a plug-in hybrid electric vehicle (PHEV), for example. 
     The term “contending” or “contention” as used herein refers to a state wherein a plurality of devices are in a competitive relationship in obtaining a single resource, such as torque or electric power. The greater the allocation of resource to a first device, the less the allocation of the resource to a second device. Under air-conditioner power cutting control which will be described below, the increased allocation of power to vehicle driving results in suppressed driving of the compressor  33 . 
     In the example that is a battery electric vehicle (BEV) illustrated in  FIG.  1   , the air conditioner  25  and the rotary electric machine  11  that serves as a drive source of the vehicle, contend for the power of a battery  10 . The battery  10  is any of a nickel hydrogen battery, a lithium ion battery, and an all solid state battery, for example. 
     The vehicle  100  includes a high-voltage circuit including the battery  10 , a step-up/step-down DC/DC converter  12 , inverters  13  and  19 , the rotary electric machine  11 , and the compressor  33 . The direct-current (DC) power output from the battery  10  is boosted, for example, by the step-up/step-down DC/DC converter  12  and is further converted to alternating-current (AC) power by the inverter  13 . The converted AC power is supplied to the rotary electric machine  11 , which is thus driven and transmits the driving force to driving wheels  16 . The DC power output from the battery  10  is also converted orthogonally at the inverter  19  and supplied to the compressor  33 . 
     The high-voltage power from the battery  10  is further stepped down by a step-down DC/DC converter  18  and supplied to a blower motor  34 A of the air conditioner  25 . The blower motor  34 A may be a DC motor, for example, and increases the rotation speed as the applied voltage increases. 
     For example, the step-down ratio is determined based on the duty ratio in drive signals (e.g., PWM signals) that define on and off of switching elements of the step-down DC/DC converter  18 , and the rotation speeds of the blower motor  34 A and a blower fan  34 B are determined accordingly. 
     The vehicle  100  further includes a steering wheel  70 , an accelerator pedal  80 , and a brake pedal  82  that are manual driving mechanisms. The extents of the driver&#39;s operation of these mechanisms are transmitted, as electric signals, for example, to a CGW-ECU  40 . In response to the signals, the CGW-ECU  40  transmits driving and steering commands to a power train and chassis ECU  44 . 
     The vehicle  100  further includes a camera unit  160 , range sensors  161  to  163 , a positioning unit  167 , and an autonomous driving ECU  41  that are autonomous driving mechanisms, which will be described below. 
     ECU 
     As illustrated in  FIG.  1   , the vehicle  100  includes a plurality of electronic controller units (ECU), which are disposed for each of different functions of the vehicle  100 . For example, the vehicle  100  includes the autonomous driving ECU  41  (autonomous driving controller), a battery ECU  42 , an air conditioner ECU  43  (air conditioner controller), and the power train and chassis ECU  44 . The vehicle  100  further includes the central gateway ECU  40  (which will be also referred to as CGW-ECU as appropriate) that is a higher-level ECU integrating these ECUs for different functions. 
     The autonomous driving ECU  41  controls autonomous driving of the vehicle  100 , as will be described in detail below. The battery ECU  42  controls the SOC and power of the battery  10 . The air conditioner ECU  43  controls the air conditioner  25 , as will be described in detailed below. The power train and chassis ECU  44  controls the rotary electric machine  11 , a steering mechanism  14 , and a brake mechanism  15 . These individual ECUs are mutually communicable via the CGW-ECU  40 , and are connected to the CGW-ECU 40  with signal lines in accordance with the CAN (Controller Area Network) standard. 
     Each of the ECUs for different functions and the CGW-ECU  40  is composed of a computer as illustrated in  FIG.  2   .  FIG.  2    illustrates a hardware configuration of the air conditioner ECU  43 . The air conditioner ECU  43  (and other ECUs) includes an input/output controller  43 C, a CPU  43 D, a RAM  43 E, a ROM  43 F, and a storage  43 G that are mutually communicable through an internal bus  43 H. 
     The input/output controller  43 C receives signals output from various sensors mounted on the vehicle  100  and outputs driving commands to on-vehicle devices such as an actuator. The CPU  43 D executes operation based on the signals received from the input/output controller  43 C and generates and transmits to the input/output controller  43 C driving commands to devices to be controlled. The RAM  43 E, the ROM  43 F, and the storage  43 G, for example, are memory elements that store control programs and data detected by the sensors. 
     Execution of the control program stored in the storage  43 G or the ROM  43 F by the CPU  43 D results in configuration of a device controller  43 A and a fogging determining unit  43 B in the air conditioner ECU  43 , as illustrated in  FIG.  1   . 
     Similarly, execution of the control program stored in the storage or ROM of the CGW-ECU 40  by the CPU results in configuration of a required power calculator  40 A in the CGW-ECU  40 . 
     Execution of the control program stored in the storage or ROM of the battery ECU  42  by the CPU results in configuration of a power comparator  42 A that is a function block in the battery ECU  42 . 
     Further, execution of the control program stored in the storage or ROM of the autonomous driving ECU  41  by the CPU results in configuration of a surroundings analyzer  41 A, a position estimator  41 B, an autonomous travelling controller  41 C, and a dynamic map memory  41 D that are function blocks in the autonomous driving ECU  41 , as illustrated in  FIG.  3   . 
     In each of the ECUs described above, the control program may be stored in a non-transitory computer readable storage medium, such as a DVD, rather than the storage or ROM, to allow the CPU to read and execute the control program. Each ECU having such a configuration similarly constitutes the various function blocks illustrated in  FIG.  1    and  FIG.  3   . 
     Switching Between Autonomous Driving and Manual Driving 
       FIG.  3    illustrates only elements highly related to autonomous driving control, among the elements illustrated in  FIG.  1   . The driving control mode of the vehicle  100  is switchable between autonomous driving control performed by the autonomous driving ECU  41  and manual driving control performed by the driver within the vehicle. 
     The autonomous driving control and the manual driving control may be changed in accordance with the road type along which the vehicle  100  travels, for example. In performing autonomous driving control at Level 2 (autonomous driving on an expressway under the driver&#39;s supervision) or Level 3 (autonomous driving on an expressway under supervision of the autonomous driving control system) based on the standards of the Society of Automotive Engineers (SAE), for example, manual driving control is performed on ordinary roads and autonomous driving control is performed on expressways. 
     As illustrated in  FIG.  4   , for example, a section of the road along an ordinary road  121  to a toll gate  122  is a manual driving section in which manual driving control is performed by the driver. A section of the road from the toll gate  122  through an entrance ramp  123  and along an expressway  124  is an autonomous driving section in which autonomous driving control is performed by the autonomous driving ECU  41 . 
     A further section of the road from an exit ramp  125  connecting to a toll gate  126  near the destination to the toll gate  126  is a driving switching preparing section for transferring the driving control from autonomous driving performed by the autonomous driving ECU  41  to manual driving performed by the driver. Then, a section along an ordinary road  127  after the vehicle  100  has passed through the toll gate  126  is a manual driving section. 
     To switch between the manual driving control and the autonomous driving control smoothly, the steering wheel  70 , for example, includes a plurality of buttons related to switching of the driving control, as illustrated in  FIG.  5   , including an autonomous driving button  71 , a cancellation button  72 , and an OK button  73 . 
     The autonomous driving button  71  is depressed when the driver wishes to execute the autonomous driving control. In response to depression of the autonomous driving button  71  while the vehicle  100  is traveling in a road section targeted for the autonomous driving control, driving control of the vehicle  100  is switched from the manual driving control to the autonomous driving control. The road section targeted for the autonomous driving control refers to an expressway described above or a road section whose map data are stored in the dynamic map memory  41 D (see  FIG.  3   ), for example. 
     In response to depression of the autonomous driving button  71  while the vehicle  100  is travelling in a road section not targeted for the autonomous driving control, the autonomous driving ECU  41  indicates, on a meter panel that is not shown, a message informing that switching to the autonomous driving control is not possible. The road section not intended for the autonomous driving control refers to an ordinary road described above or a road section whose map data are not stored in the dynamic map memory  41 D (see  FIG.  3   ). 
     When the vehicle  100  is travelling in a road section targeted for the autonomous driving control but is under the manual driving control, the autonomous driving ECU  41  indicates, on the meter panel not shown, for example, a message that encourages switching to the autonomous driving control. In response to the driver&#39;s depressing of the OK button  73 , driving control of the vehicle  100  is switched from the manual driving control to the autonomous driving control. In response to depression of the cancellation button  72  by the driver, driving control according to manual driving continues. 
     The vehicle  100  travelling in the driving switching preparing section (see  FIG.  4   ) is controlled under the autonomous driving control. During the autonomous driving control in the driving switching preparing section, the autonomous driving ECU  41  indicates, on the meter panel, for example, a message informing that the autonomous driving control is to be changed to the manual driving control. 
     In response to depression of the OK button  73  by the driver after the above message is indicated, the driving control of the vehicle  100  is changed from the autonomous driving control to the manual driving control. The driving control of the vehicle  100  may also be changed from the autonomous driving control to the manual driving control in response to operation of the steering wheel  70  with a predetermined torque or more, in place of depression of the OK button  73 . Further, the driving control of the vehicle  100  may also be changed from the autonomous driving control to the manual driving control in response to operation of the accelerator pedal  80  (see  FIG.  1   ) or the brake pedal  82  with the steering wheel  70  being retained. In addition to the road type such as an ordinary road or expressway, the weather or device failure may be the basis to determine the manual driving section, the autonomous driving section, and the driving switching preparing section. 
     In response to the weather surrounding the vehicle  100  becoming inclement or device malfunction, such as optical axis offset, of the camera unit  160  (see  FIG.  1   , for example) during execution of the autonomous driving control, for example, a message informing switching from the autonomous driving control to the manual driving control is indicated on the meter panel and the like, similar to the case of travelling in the driving switching preparing section described above. 
     In response to depression of the OK button  73  by the driver or operation of the steering wheel  70 , for example, after the above message is indicated, the driving control of the vehicle  100  is switched from the autonomous driving control to the manual driving control. 
     Meanwhile, in the absence of the driver&#39;s operation of the OK button  73 , for example, for a predetermined time period after indication of the message, the autonomous driving ECU  41  performs retraction control by moving the vehicle  100  to an edge of the road, for example. 
     Autonomous Driving Control System 
     As illustrated in  FIG.  3   , the vehicle  100  includes sensors for recognizing the surroundings, including the camera unit  160 , a lidar sensor  161 , and front-side radar sensors  162 A and  162 B, and a front-center radar sensor  163 . The vehicle  100  further includes a sensor for estimating the position of the vehicle  100 , or a positioning unit  167 . 
       FIG.  6    illustrates a front portion of the vehicle  100 . The vehicle  100  includes the front-center radar sensor  163  on a front face of the vehicle  100  at the back of an emblem in the center along the vehicle width, for example. The vehicle  100  further includes front-side radar sensors  162 A and  162 B at respective opposite side portions on the front face of the vehicle  100 . Each of these radar sensors is composed of a millimeter-wave radar, for example. 
     The vehicle  100  further includes the lidar sensor  161  on the front face of the vehicle  100  in the center portion along the vehicle width below a portion where the license plate is attached. The lidar sensor  161  employs a technique of measuring the distance to a peripheral object with LiDAR (Light Detection and Ranging) or laser light such as infrared light. The lidar sensor  161  is a solid-state unit, for example, which can acquire three-dimensional point data regarding the surrounding environment of the vehicle  100 . 
     The camera unit  160  is disposed on a rear side of a windshield glass  110  or a face of the windshield glass  110  exposed to the vehicle cabin. The camera unit  160  is disposed in the upper center portion of the windshield glass  110  along the vehicle width, for example. 
     As illustrated in  FIG.  7   , the camera unit  160  includes cameras  160 A and  160 B, a casing  160 C, and a camera heater  160 D. The cameras  160 A and  160 B or stereo cameras are able to capture images in front of the vehicle through the windshield glass  110 . 
     The cameras  160 A and  160 B are secured on the casing  160 C facing forward of the vehicle with the optical axes being substantially parallel to each other. The casing  160 C has a shape similar to that of a dustpan and includes a bottom wall  160 C 1  extending from under the camera  160 A and  160 B toward the front of the vehicle, with the front end of the bottom wall  160 C 1  in contact with the rear face (facing vehicle cabin interior) of the windshield glass  110 . 
     The camera heater  160 D is disposed on the bottom wall  160 C 1  of the casing  160 C. The camera heater  160 D, which may be an electric wire, includes a temperature sensor  160 E 
     The temperature sensor  160 E measures the temperature of a region of the windshield glass  110  within the field of view of the cameras  160 A and  160 B. The temperature sensor  160 E measures, for example, the temperature of the region on the windshield glass  110  including points that intersect with the optical axes of the cameras  160 A and  160 B. In response to the temperature detected by the temperature sensor  160 E being lower than a predetermined temperature, for example, the autonomous driving ECU  41  operates the camera heater  160 D to defog the region of the windshield glass  110  around the cameras  160 A and  160 B. 
     Referring back to  FIG.  3   , the positioning unit  167  performs measurements by an artificial satellite and may be a global navigation satellite system, for example. 
     As described above, execution of the control program stored in the storage or ROM of the autonomous driving ECU  41  (autonomous driving controller) by the CPU results in configuration of the function blocks, including the surroundings analyzer  41 A, the position estimator  41 B, and the autonomous travelling controller  41 C in the autonomous driving ECU  41 . The dynamic map memory  41 D is further configured in the autonomous driving ECU  41 , as a memory unit. 
     The dynamic map memory  41 D stores dynamic map as map data. The dynamic map is a three-dimensional map including, for example, data on the position and three-dimensional shape of a road. The three-dimensional shape of a road includes gradient and width, for example. The dynamic map further includes position data of lines on the road, pedestrian crossings, and stop lines, for example. The dynamic map also includes data on positions and three-dimensional shapes of structures surrounding the road, such as stops, buildings, or signals. The dynamic map further includes data on the positions or shapes of parking lots. 
     The dynamic map further includes, in addition to the static information described above, dynamic information or dynamic data including traffic restriction and construction information, accident or traffic jam information, pedestrian information, or signal information. For example, the dynamic map includes geographic coordinates including latitude and longitude. 
     The surroundings analyzer  41 A acquires captured images from the cameras  160 A and  160 B, and performs image recognition based on a known deep learning technique with regard to the captured images. The image recognition is performed to detect objects within the captured images and recognize attributes (vehicle, passenger, structure, and the like) of the objects. 
     The surroundings analyzer  41 A further acquires three-dimensional points data from the lidar sensor  161 , and creates peripheral data including the image-recognized captured image superposed on the coordinates of the three-dimensional points data. The peripheral data enable detection of the distance from the vehicle  100  of an object having a certain attribute. 
     The peripheral data may further reflect range information from the front-side radar sensors  162 A and  162 B (see  FIG.  6   ) or the front-center radar sensor  163 . For example, the range information of regions that cannot be measured by the lidar sensor  161  is compensated with range information from these radar sensors. The peripheral data generated by the surroundings analyzer  41 A are transmitted to the autonomous travelling controller  41 C. 
     The position estimator  41 B acquires positional information (latitude and longitude) of the vehicle  100  from the positioning unit  167 . The position estimator  41 B acquires the positional information from the artificial satellite. The positional information (vehicle positional information) thus acquired is transmitted to the autonomous travelling controller  41 C. 
     The autonomous travelling controller  41 C controls travelling of the vehicle  100  based on the map data stored in the dynamic map memory  41 D, the positional information (vehicle positional information) transmitted from the position estimator  41 B, and the peripheral data transmitted from the surroundings analyzer  41 A. 
     For example, a global route is determined from the road information and destination information stored in the map data, and the positional information. A local route is further determined from the peripheral data. The autonomous travelling controller  41 C combines the global data and the local data to generate steering commands and speed commands, which are then transmitted to the power train and chassis ECU  44 . The power train and chassis ECU  44 , based on the received steering commands and speed commands, controls the steering mechanism  14 , the brake mechanism  15 , the step-up/step-down DC/DC converter  12 , and the inverter  13 . 
     Air Conditioner 
     As illustrated in  FIG.  1    and  FIG.  8   , the air conditioner  25  includes electric devices including the step-down DC/DC converter  18 , the inverter  19 , the compressor  33 , the blower motor  34 A, and an actuator  68 . Referring further to  FIG.  8   , the air conditioner  25  includes devices disposed on the flow passage of the refrigerant, including, in addition to the compressor  33 , an outdoor condenser  30  (radiator), an evaporator  31 , an indoor condenser  32 , expansion valves  35  and  36 , an accumulator  37 , an electromagnetic valve  38 , and a check valve  39 . In addition, the air conditioner  25  includes controllers, including the air conditioner ECU  43  and an air conditioner control panel  50 . 
     Referring to  FIG.  8   , the air conditioner  25  for vehicle cabin mounted in the vehicle  100  is a heat pump air conditioner. Devices of the air conditioner  25 , including the compressor  33 , the blower  34 , and the actuator  68  (see  FIG.  1   ), are electric machines to be driven with the power of the battery  10 . 
     As illustrated in  FIG.  8   , the blower  34  includes the blower motor  34 A and the blower fan  34 B. The blower motor  34 A may be a DC motor, for example, and increases the rotation speed with the increase of the applied voltage. The power from the battery  10  is supplied, via the step-down DC/DC converter  18 , to the blower motor  34 A. A drive signal (a PWM signal, for example) that determines on or off of a switching element of the step-down DC/DC converter  18  is generated by the device controller  43 A of the air conditioner ECU  43 . The step-down ratio of the step-down DC/DC converter  18  is determined based on the duty ratio of the drive signal to the step-down DC/DC converter  18 , and the rotation speeds of the blower motor  34 A and the blower fan  34 B are determined in accordance with the step-down ratio. 
     The compressor  33  is a motor-installed electrically driven device, and receives electric power supplied from the battery  10  via the inverter  19 , as illustrated in  FIG.  1   . A drive signal (a PWM signal, for example) that determines on or off of a switching element of the inverter  19  is generated by the device controller  43 A of the air conditioner ECU  43 . The rotation speed of the compressor  33  is determined based on the duty ratio of the drive signal. 
     The electrical compressor  33 , such as a motor-driven compressor  33 , requires more electrical power to obtain driving torque of the compressor  33 , as compared to a conventional compressor  33  driven by the internal combustion engine. The electric devices in the vehicle  100  that require the greatest amounts of electric power are the rotary electric machine  11  that is a drive source, and the compressor  33  consumes the second greatest amount of electric power. For example, the audio system or the navigation system consumes power in the units of watt W, whereas the compressor  33  consumes power in the units of kilowatt kW. 
     The air conditioner  25  includes a duct  60  (see  FIG.  8   ) that controls the air flow. The duct  60  includes, at an upstream end, an inside air inlet  61  and an outside air inlet  62 . The inside air inlet  61  is disposed within the vehicle cabin, and the outside air inlet  62  is disposed outside the vehicle. The mixture ratio of the inside air and the outside air to be taken into the duct  60  is determined in accordance with the setting angle of an inside/outside air switching door  67 A. 
     The air taken through at least one of the inside air inlet  61  and the outside air inlet  62  is absorbed by the blower fan  34 B and passes the evaporator  31  via an air cleaner  66 . When an air mix door  67 B closes the indoor condenser  32 , the air bypasses the indoor condenser  32  and flows. The air is also discharged into the vehicle cabin from at least any one of a front defroster duct  63 , a face or upper register  64 , and a foot or lower register  65 . The amounts of discharge of the air from the front defroster duct  63 , the upper register  64 , and the lower register  65  are determined in accordance with the degrees of opening of a defroster door  67 C, a face or upper door  67 D, and a foot or lower door  67 E, respectively. 
     The degrees of opening of the inside/outside air switching door  67 A, the air mix door  67 B, the defroster door  67 C, the upper door  67 D, and the lower door  67 E (illustrated as  67  in  FIG.  1   ) are adjusted by the actuator  68  illustrated in  FIG.  1   . The device controller  43 A of the air conditioner ECU  43  controls the degrees of opening of these doors based on the setting, for example, of a vent selection switch  59  (see  FIG.  5   ) and other devices. 
       FIG.  9    illustrates the flow of a refrigerant during use of the heating function of the air conditioner  25 . In heating, the air mix door  67 B is completely open to the room condenser  32 . When an inside/outside air changing switch or an air recirculation switch  56  (see  FIG.  5   ) for switching between inside air and outside air is turned off, the outside air is introduced into the duct  60  through the outside air inlet  62 . 
     The air (outside air) is introduced from the blower  34  to the room condenser  32  as the high-temperature refrigerant compressed by the compressor  33  passes through the room condenser  32 . The air having passed through the room condenser  32 , which is hot air, is discharged from at least one of the front defroster duct  63 , the upper register  64 , or the lower register  65  into the vehicle cabin. 
     The refrigerant passing through the room condenser  32  is decompressed by the expansion valve  35 . The decompressed refrigerant having a temperature below the outside air absorbs heat at the time of passing the outdoor condenser  30 . The refrigerant is further compressed by the compressor  33  via the electromagnetic valve  38  and the accumulator  37 . 
       FIG.  10    illustrates the flow of the refrigerant during use of the cooling function of the air conditioner  25 . In cooling, the air mix door  67 B is completely closed with respect to the room condenser  32 . When the air recirculation switch  56  (see  FIG.  5   ) is turned off, the outside air is introduced into the duct  60  through the outside air inlet  62 . 
     The high-temperature refrigerant compressed by the compressor  33  is decompressed at the expansion valve  35  via the room condenser  32 . The decompressed refrigerant having a higher temperature than the outside air dissipates heat at the time of passing the outside condenser  30 . The refrigerant is further decompressed at the expansion valve  36  into a mist state with a low temperature and a low pressure. 
     As this refrigerant passes the evaporator  31 , the air from the blower  34  also passes the evaporator  31 , and the cool air is to be supplied to the vehicle cabin. The refrigerant after heat exchange is separated into a gas refrigerant and a liquid refrigerant by the accumulator  37 , and the gas refrigerant is delivered to the compressor  33 . 
       FIG.  11    illustrates the flow of the refrigerant during use of the dehumidification function of the air conditioner  25 . The operation of the air conditioner  25  during execution of the dehumidification is substantially the same as that at the time of cooling; however, the air mix door  67 B is opened to the room condenser  32 . 
     The driving conditions of the compressor  33  are set such that the air passing the evaporator  31  has a temperature that is lower than the set temperature. Specifically, the air having a temperature lower than the set temperature temporarily reduces the saturated vapor volume of the air and removes the water content within the air as water drops. Subsequently, the air is further allowed to pass through the room condenser  32  to thereby raise the air temperature to the set temperature. This allows dry air to be supplied into the vehicle cabin. 
     Air Conditioner Control 
     As illustrated in  FIG.  5   , the operation of the air conditioner  25  is set by the air conditioner control panel  50 , which is disposed on the instrument panel near the driver&#39;s seat, for example. 
     The air conditioner control panel  50  may be a touch screen having an input portion and a display portion overlapped with each other. The air conditioner control panel  50  includes air volume control buttons  51 A and  51 B, temperature setting buttons  52 A and  52 B, an auto switch  53 , and a blower switch  54 . The air conditioner control panel  50  further includes an air conditioner switch  55 , the air recirculation switch  56 , a display  57 , a defroster switch  58 A, a rear defogger switch  58 B, and the vent selection switch  59 . These buttons and switches have known functions, which will not be described here. 
     Signals generated by operation of the various switches and buttons of the air conditioner control panel  50  are transmitted to the air conditioner ECU  43  (air conditioner controller, see  FIG.  1   ). The device controller  43 A of the air conditioner ECU  43  can switch the control mode of the air conditioner  25  between manual control and autonomous control in accordance with inputs to the air conditioner control panel  50 . 
     For example, in response to an ON operation of the auto switch  53 , the air conditioner ECU  43  performs autonomous control with respect to the air conditioner  25 . The ON operation refers, for example, to changing of indication of a lamp (or its image) of the auto switch  53  from light-off indication to light-on indication. 
     Meanwhile, the operation to change the indication of the lamp from the light-on state to the light-off state is referred to as an OFF operation. In response to the OFF operation of the auto switch  53 , the air conditioner ECU  43  executes manual control to control the air conditioner  25  in accordance with the operation of the various switches of the air conditioner control panel  50 . 
     During the ON operation of the air recirculation switch  56 , the inside air is circulated within the vehicle cabin. As the circulation of the inside air increases moisture of the air within the vehicle cabin and results in condensation and fogging on the windshield glass  110 , an occupant such as a driver turns on the defroster switch  58 A. 
     In response to this ON operation, the device controller  43 A of the air conditioner ECU  43  performs the following defogging operation. Specifically, the device controller  43 A sets the air conditioner  25  to the dehumidification operation state illustrated in  FIG.  11   . The device controller  43 A further operates the inside/outside air switching door  67 A to introduce the outside air and completely open the defroster door  67 C. The device controller  43 A also maximizes the rotation speed of the blower fan  34 B. This operation dehumidifies the outside air introduced into the duct  60  at the time of passing the evaporator  31 , and supplies a large volume of the dehumidified air (dry air) from the front defroster duct  63  to the windshield glass  110 , thereby defogging the windshield glass  110 . 
     In autonomous control, in contrast, autonomous air conditioner control (including the defogging operation) is executed. For the autonomous control, the vehicle  100  includes a plurality of sensors. As illustrated in  FIG.  6   , for example, the vehicle  100  includes an outside air temperature sensor  164 , an inside air temperature sensor  165 , and a humidity sensor  166 . The outside air temperature sensor  164  is disposed on the front bumper on the front face of the vehicle, for example. The inside air temperature sensor  165  is disposed on a steering column within the vehicle cabin, for example. The humidity sensor  166  is disposed on, for example, a rear face of the windshield glass  110  or a face exposed to the vehicle cabin. In the example illustrated in  FIG.  6   , for example, the humidity sensor  166  is disposed near the camera unit  160 . 
     Detected values from the outside air temperature sensor  164 , the inside air temperature sensor  165 , and the humidity sensor  166  are transmitted to the fogging determining unit  43 B of the air conditioner ECU  43 . The fogging determining unit  43 B, based on the detected values from the outside air temperature sensor  164 , the inside air temperature sensor  165 , and the humidity sensor  166 , determines whether fogging occurs on the windshield glass  110 . 
     For example, in response to the outside air temperature detected by the outside air temperature sensor  164  being a threshold value or lower, the fogging determining unit  43 B determines occurrence of fogging of the windshield glass  110 . In response to the occurrence of fogging determined by the fogging determining unit  43 B, the device controller  43 A executes the defogging operation described above. After a predetermined time period (20 seconds, for example) of continued defogging operation, the fogging determining unit  43 B determines that fogging has been eliminated. In response, the device controller  43 A restores the control state before the defogging operation. 
     Alternatively, occurrence of fogging of the windshield glass  110  may be determined based on the detection result of the humidity sensor  166 . In response to the humidity near the windshield glass  110  detected by the humidity sensor  166  being a predetermined threshold humidity or higher, the fogging determining unit  43 B determines occurrence of fogging of the windshield glass  110 . In response to this determination, the device controller  43 A performs the defogging operation described above. Subsequently, in response to the humidity detected by the humidity sensor  166  being below the threshold humidity, the fogging determining unit  43 B determines defogging of the windshield glass  110 . In response, the device controller  43 A restores the control state before the defogging operation. 
     Occurrence of fogging of the windshield glass  110  may also be determined based on a difference between the temperature detected by the outside air temperature sensor  164  and the temperature detected by the inside air temperature sensor  165 . In response to the temperature detected by the outside air temperature sensor  164  being the threshold temperature or lower and the difference determined by subtracting the temperature detected by the outside air temperature sensor  164  from the temperature detected by the inside air temperature sensor  165  being a predetermined threshold temperature difference or greater, for example, the fogging determining unit  43 B determines occurrence of fogging on the windshield glass  110 . In response to this determination, the device controller  43 A executes the defogging operation described above. After a predetermined time period (20 seconds, for example) of continued defogging operation, the fogging determining unit  43 B determines defogging. In response, the device controller  43 A restores the control state before the defogging operation. 
     In addition, fogging may be determined based on weather information acquired from an external weather forecasting organization, for example. The fogging determining unit  43 B may acquire weather information of an area where the vehicle  100  is travelling. The fogging determining unit  43 B further determines whether fogging occurs on the windshield glass  110  based on the outside air humidity information included in the weather information. 
     Air Conditioner Power Cutting Control 
     As described above, the compressor  33  and the rotary electric machine  11  contend for power of the battery  10 . To secure the vehicle driving force during the autonomous control of the air conditioner  25 , the air conditioner power cutting control can be executed. The air conditioner power cutting control is performed to control driving of the compressor  33  in accordance with the required vehicle driving force. 
     As illustrated in  FIG.  1   , the required power calculator  40 A of the CGW-ECU  40  receives, from the autonomous driving ECU  41 , data of power to be supplied to the rotary electric machine  11  that is a vehicle drive source, or data of required driving power or required vehicle driving force. The required power calculator  40 A further receives, from the air conditioner ECU  43 , data of power to be supplied to the air conditioner  25 , particularly to the compressor  33 , or data of required air conditioning power. The required power calculator  40 A further determines, and sends to the battery ECU  42 , data of the required total power including the required driving power and the required air conditioning power. 
     The battery ECU  42  determines State of Charge (SOC) or charging rate of the battery  10  based on detected values from a current sensor  10 A, a voltage sensor  10 B, and a temperature sensor  10 C, for example. The battery ECU  42  further determines State of Power (SOP) or chargeable/dischargeable power of the battery  10  based on the determined SOC. The SOC and SOP can be obtained in known manners, which will not be described here. 
     The battery ECU  42  further determines whether or not the value of the required total power received from the CGW-ECU  40  exceeds the SOP of the battery  10 . In response to the required total power exceeding the SOP, the battery ECU  42  requests the CGW-ECU  40  for reduction of the required total power. 
     The CGW-ECU  40 , in response, cuts down the required air conditioning power of the required total power, and instructs the air conditioner ECU  43  to execute the air conditioner power cutting control. For example, the CGW-ECU  40  reduces power required for driving the compressor  33  of the required total power. 
     In response to the instruction to execute the air conditioner power cutting control, the device controller  43 A of the air conditioner ECU  43  regulates driving of the compressor  33 . For example, the device controller  43 A controls driving of the compressor  33  to reduce the output of the compressor  33  by reducing the required output by a predetermined ratio. 
     In a typical example of the air conditioner power cutting control, the power required for driving the compressor  33  is reduced (to 0). In response, the device controller  43 A stops the inverter  19  to thereby stop supply of power to the compressor  33 . This temporarily stops temperature regulation by the air conditioner  25 , and the outside air or inside air (with unregulated temperature) is delivered into the vehicle cabin by the blower  34 , for example. 
     When fogging occurs on the windshield glass  110  due to regulation of driving of the compressor  33  under the air conditioner power cutting control, the driver or occupant depresses the defroster switch  58 A (see  FIG.  5   ). This operation interrupts the autonomous control of the air conditioner  25  and therefore interrupts the air conditioner power cutting control that is a subordinate control flow of the autonomous control. 
     In such a case, the CGW-ECU  40  cuts down the required driving power from the required total power. This reduces the driving force of the vehicle relative to the required value (or required vehicle driving force); however, the defogging function is secured. 
     Air Conditioner Control in Autonomous Driving section 
     During execution of the autonomous driving control by the autonomous driving ECU  41 ; that is, while the vehicle  100  is travelling in the autonomous driving section, the various sensors including the camera unit  160  are used to confirm the surroundings ahead of the vehicle  100 . At this time, as it is only required that the field of view near the camera unit  160  is secured for the autonomous driving control, defogging of the entire windshield glass  110  is not necessary. 
     Therefore, during execution of the autonomous driving control with the autonomous control being selected for the air conditioner  25 , the fogging determining unit  43 B loosens the criteria for determining fogging relative to that used during execution of the manual driving control. For example, the fogging determining unit  43 B stops fogging determination during execution of the autonomous driving control. 
     The a power comparator  42 A of the battery ECU  42  changes the determination criteria to further promote performance of the air conditioner power cutting control as compared to that used during execution of the manual driving control. For example, the power comparator  42 A uses, as the reference value, a value which is a predetermined ratio (80%, for example) of the SOP of the battery  10 . In response to the value of the required total power received from the CGW-ECU  40  exceeding the reference value, the battery ECU  42  requests the CGW-ECU  40  to reduce the required total power. 
     In response to this request, the CGW-ECU  40  cuts down the required air conditioning power of the required total power and instructs the air conditioner ECU  43  to execute the air conditioner power cutting control. For example, the CGW-ECU  40  cuts down the power required for driving the compressor  33  from the required total power. 
     As described above, during execution of the autonomous driving control and the autonomous control for the air conditioner, the fogging determination is stopped, and the criteria for performing the air conditioner power cutting control are loosened (the control becomes easier to execute). Meanwhile, the temperature detected by the temperature sensor  160 E (see  FIG.  7   ) of the camera unit  160  is continuously transmitted to the autonomous driving ECU  41 . The autonomous driving ECU  41 , in accordance with the temperature detected by the temperature sensor  160 E, operates the camera heater  160 D to maintain good field of view around the cameras  160 A and  160 B. 
     For example, in response to the temperature detected by the temperature sensor  160 E being below the threshold temperature, the autonomous driving ECU  41  operates the camera heater  160 D to defog the area of the windshield glass  110  around the cameras  160 A and  160 B. 
     However, during execution of the autonomous driving control but without the autonomous control being selected, the normal determination criteria are used to determine fogging. Further, the air conditioner power cutting control is executed only during execution of the autonomous control of the air conditioner  25  and would not be executed without the autonomous control being selected. 
     Thus, in response to fogging of the windshield glass  110  during execution of the autonomous driving control, for example, the occupant depresses the defroster switch  58 A to actuate the defogging operation described above, thereby defogging the windshield glass  110 . 
     Air Conditioner Control in Driving Switching Preparing Section 
     Based on entry of the vehicle  100  into the driving switching preparing section to transfer to manual driving after travelling the autonomous driving section, the air conditioner ECU  43  performs the air conditioner power cutting setting flow illustrated in  FIG.  12   . The air conditioner ECU  43  receives, from the autonomous travelling controller  41 C (see  FIG.  3   ) of the autonomous driving ECU  41 , a switching request from autonomous driving to manual driving, via the CGW-ECU  40 . 
     In response to the switching request, the fogging determining unit  43 B of the air conditioner ECU  43  resumes fogging determination that has been stopped during execution of the autonomous driving control and the air conditioner autonomous control, and reflects the determination result in the control of the air conditioner  25  (S 10 ). 
     Further, the device controller  43 A determines whether or not autonomous control is selected for control setting of the air conditioner  25  (S 20 ). In response to the autonomous control not being selected, which means that the air conditioner power cutting control would not be executed, the air conditioner power cutting setting flow ends. 
     In response to the autonomous control being selected in step S 20 , the device controller  43 A sets prohibition of performance of the air conditioner power cutting control (S 30 ). This prohibition setting is transmitted to the CGW-ECU  40 . 
     Setting prohibition of the air conditioner power cutting control allows the required power calculator  40 A of the CGW-ECU  40  to cut down the required driving power from the required total power in response to the request to reduce the required total power by the power comparator  42 A of the battery ECU  42 . 
     This reduces the driving force of the vehicle  100  relative to the required driving force. However, the prohibition of the air conditioner power cutting control secures defogging of the windshield glass  110  at the time of switching from autonomous driving to manual driving. 
     Particularly, the windshield glass  110  is more likely to fog (that is, is less likely to defog) while the vehicle  100  is travelling in the autonomous driving section than while travelling in the manual driving section. Securing the windshield glass  110  defogging function in the driving switching preparing section would reliably eliminate the fog that has occurred during travelling in the autonomous driving section. 
     Once the operation control of the vehicle  100  is switched to manual driving after the driving switching preparing section, the prohibition setting for the air conditioner power cutting control may be cancelled. In other words, the air conditioner power cutting control is executable under the autonomous control of the air conditioner  25 . 
     First Further Example Air Conditioner Control in Driving Switching Preparing Section 
       FIG.  13    shows a first further example air conditioner power cutting setting flow. In the steps shown in  FIG.  13    denoted with the same reference numerals as those in  FIG.  12   , the same processes are performed, and description thereof will be omitted as appropriate. 
     Referring to  FIG.  13   , a step S 25  is added between step S 20  and step S 30 , for determining whether or not the fogging determining unit  43 B determines occurrence of fogging on the windshield glass  110 . In response to the fogging determining unit  43 B determining occurrence of fogging, the device controller  43 A sets prohibition of air conditioner power cutting (S 30 ). In response to the fogging determining unit  43 B determining no fogging, with prohibition of air conditioner power cutting not being set, that is, with the air conditioner power cutting being set to be effective, the air conditioner power cutting setting flow ends. 
     This flow sets the air conditioner power cutting to be effective based on the clear condition that the windshield glass  110  is not foggy; that is, the defogging operation is not to be performed. This enables the required power calculator  40 A to cut down the required air conditioning power of the required total power in response to a request to reduce the required total power from the required power calculator  40 A of the CGW-ECU  40  to the power comparator  42 A of the battery ECU  42 , thereby securing the vehicle driving force. 
     Second Further Example Air Conditioner Control in Driving Switching Preparing Section 
       FIG.  14    shows a second further example air conditioner power cutting setting flow. In the steps shown in  FIG.  14    denoted with the same reference numerals as those in  FIG.  13   , the same processes are performed, and description thereof will be omitted below as appropriate. 
     Referring to  FIG.  14   , after performing of the air conditioner power cutting control is prohibited in step S 30 , the fogging determining unit  43 B performs the fogging determination described above and then determines whether fogging on the windshield glass  110  has been eliminated (S 35 ). In response to determining that fogging is not eliminated, the fogging determining unit  43 B returns to the process in step S 35 . 
     In response to determining that fogging on the windshield glass  110  has been eliminated in step S 35 , the fogging determining unit  43 B transmits, via the CGW-ECU  40 , a signal indicative of elimination of fogging to the autonomous driving ECU  41 . The autonomous travelling controller  41 C (see  FIG.  3   ) of the autonomous driving ECU  41  then displays, on the meter panel, for example, within the vehicle cabin, a message informing switch from autonomous driving control to manual driving control (S 40 ). 
     This flow allows the autonomous driving ECU  41  to continue the autonomous driving control until the fogging determining unit  43 B determines elimination of fogging of the windshield glass  110 . In other words, control is transferred from autonomous driving to manual driving with fogging on the windshield glass  110  being eliminated. Transfer of control to manual driving after the driver&#39;s good field of view has been established enhances the driver&#39;s sense of security. 
     Vehicle including Internal Combustion Engine as Drive Source 
     While in the above embodiments, the vehicle  100  includes only the rotary electric machine  11  as a drive source, the air conditioner control according to the present embodiments is also applicable in the vehicle  100  including an internal combustion engine, as a drive source, in place of or in addition to the rotary electric machine  11 . 
     In this configuration, the compressor  33  is driven by the internal combustion engine. As such, the compressor  33  and the driving wheels  16  contend for the torque of the internal combustion engine. To secure the vehicle driving force, the air conditioner power cutting control is performed as appropriate. 
     In this configuration, for convenience, the required power calculator  40 A of the CGW-ECU  40  is referred to as a required torque calculator. The required torque calculator receives, from the autonomous driving ECU  41 , a value of the required driving torque (required vehicle driving force) for the internal combustion engine. The required torque calculator further receives, from the air conditioner ECU  43 , a value of the torque for the compressor  33  or the required air conditioning torque. The required torque calculator further obtains a value of the required total torque including the required driving torque and the required air conditioning torque, and transmits the obtained value to the engine ECU that is not shown. 
     The engine ECU determines whether the received value of the required total torque exceeds the value of the maximum output torque of a known internal combustion engine. In response to determining that the required total torque exceeds the maximum output torque, the engine ECU requests the CGW-ECU  40  for reduction of the required total torque. 
     In response, the CGW-ECU  40  reduces the required air conditioning torque of the required total torque, and instructs the air conditioner ECU  43  to execute the air conditioner power cutting control. For example, the CGW-ECU 40  cuts down the torque required for driving the compressor  33  of the required total torque. 
     Further, when the vehicle  100  is travelling in the driving switching preparing section described above, the air conditioner ECU  43  and the autonomous driving ECU  41  perform the air conditioner power cutting setting flow illustrated in  FIG.  12    to  FIG.  14   , and determine whether or not the air conditioner power cutting control is prohibited as described above. 
     The present disclosure is not limited to the present embodiments described above, and includes all changes and modifications without departing from the technical scope or the essence of the present disclosure defined by the claims.