Vehicle control method and device

Abstract

A vehicle having an automatic driving function is provided with: an alternator (2); a starting motor (5); a load group A (21) including one of two automatic driving electrical loads constituting the redundant system and a load group B (22) including the other; a lead acid battery (6); and a standby lithium ion battery (7). If the temperature of the lithium ion battery (7) is greater than or equal to the idle stop prohibition temperature (T1), the idle stop control is prohibited. The idle stop prohibition temperature (T1) is lower than an automatic driving prohibition temperature (T2) at which automatic driving is prohibited.

Description

Technical Field

[0001] The present invention relates to a vehicle control in which, in a vehicle having an automatic driving function, a fuel efficiency improvement control such as power supply securing of an electric load for automatic driving and idling stop control are appropriately combined. Background Art

[0002] For vehicles with autonomous driving functions (including so-called driving assistance functions) whose control systems operate the vehicle's steering, braking, etc., a power supply structure with high reliability is required as a power supply for autonomous driving electrical loads including the electric actuators that implement the operations and their control circuits.

[0003] Patent document 1 discloses a structure in which, in addition to a main battery composed of a lead battery that supplies power to an electric load required for normal driving, an additional battery composed of a lithium-ion battery that supplies power to an electric load for autonomous driving, such as an ADAS actuator, is provided. This structure is divided into a first load circuit including a main battery and a general electric load, and a second load circuit including an additional battery and an electric load for autonomous driving, and a circuit disconnection mechanism is provided between the two. Furthermore, the voltage fluctuation of each load circuit is monitored to control the disconnection / connection of the two load circuits.

[0004] However, Patent Document 1 does not disclose the contents related to the idling stop control, and does not disclose how to maintain the automatic driving function when the idling stop control is applied.

[0005] Patent Document 2 discloses a structure in which a vehicle having an idle stop function has a main battery composed of a lithium-ion battery and a sub-battery composed of a lead battery. The main battery is used for normal power supply including cranking in a normal temperature range, and the sub-battery is used for power supply to a starter when the engine temperature is in a low temperature range or a high temperature range during starting.

[0006] However, Patent Document 2 does not particularly consider ensuring power supply for maintaining the automatic driving function.

[0007] Patent Document 1: Japanese Patent Application Publication No. 2017-177857

[0008] Patent Document 2: Japanese Patent Application Publication No. 2008-167652 Summary of the invention

[0009] The present invention relates to a vehicle control method.

[0010] The vehicle has:

[0011] engine;

[0012] a generator driven by the engine to generate electricity; and

[0013] The lithium-ion battery is charged by the electric power generated by the generator and supplies the electric power required for the autonomous driving of the vehicle to the autonomous driving electric load.

[0014] When a predetermined condition is satisfied, a fuel efficiency improvement control for reducing the driving energy of the generator is executed.

[0015] The fuel efficiency improvement control is prohibited when the temperature of the lithium ion battery is greater than or equal to a predetermined temperature.

[0016] By implementing fuel efficiency improvement controls such as idle stop control that stops the engine and power generation control that makes the power generation of the generator substantially zero, it is possible to reduce the driving energy of the generator and even reduce fuel consumption. In order for this fuel efficiency improvement control to have a practical effect, the lithium-ion battery needs to be charged during the period of generator-based power generation other than during the fuel efficiency improvement control, and the charged power is supplied to the electrical loads including the autonomous driving electrical loads during the fuel efficiency improvement control. Therefore, the time and frequency of charging and discharging increase, and the temperature of the lithium-ion battery tends to rise. If the temperature of the lithium-ion battery rises excessively, the reliability of the autonomous driving function decreases. For example, the protection function of the lithium-ion battery itself works and the autonomous driving function cannot be maintained.

[0017] According to the present invention, by prohibiting the fuel efficiency improvement control when the temperature of the lithium-ion battery is equal to or higher than a predetermined temperature, it is possible to avoid an excessive temperature increase that may cause a decrease in the reliability of the automatic driving function. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is an explanatory diagram showing the system configuration of a power supply system according to one embodiment.

[0019] Figure 2 It is an explanatory diagram showing the basic operation of the power supply system according to one embodiment.

[0020] Figure 3 It is a timing chart showing the charge and discharge of the lead-acid battery and the lithium-ion battery during the idling stop control.

[0021] Figure 4 It is an explanatory diagram showing the operation in the idling stop control. DETAILED DESCRIPTION

[0022] Figure 1This is an explanatory diagram showing the system structure of a power supply system of a vehicle with an automatic driving function according to one embodiment. The vehicle of one embodiment is a vehicle that basically runs using the power of an engine 1. As the engine 1, for example, a spark ignition engine, that is, a gasoline engine can be used, but it can also be a diesel engine that performs compression self-ignition. The engine 1 has a generator, such as an AC generator 2. The AC generator 2 is driven by a crankshaft pulley 4 of the engine 1 via a belt drive mechanism 3. The engine 1 also has a starter motor 5 as a starting motor. The starter motor 5 is a general structure having a pinion gear that engages / disengages with a ring gear (not shown) of the engine 1.

[0023] The vehicle includes multiple electrical loads, in one embodiment, such as Figure 1 As shown schematically, the plurality of electrical loads are roughly divided into a load group A 21 and a load group B 22. The load group A 21 includes various electrical loads generally required for vehicle driving, such as the fuel system, ignition system, and control system of the engine 1, lighting, air conditioning, audio equipment, and other electrical components. In addition, the load group A 21 also includes a system of loads (equivalent to the second electrical load in the technical solution) of an autonomous driving electrical load required for the autonomous driving of the vehicle, which is constituted as a redundant system.

[0024] The load group B 22 includes loads of another system (corresponding to the first electric load in the technical claim) which is an automatic driving electric load necessary for automatic driving of the vehicle configured as a redundant system.

[0025] The above two electric loads for autonomous driving constituted as redundant systems have substantially the same functions. For example, regarding the level 2 autonomous driving function, the throttle valve of the engine 1 and the brake of the vehicle are controlled by the driving assistance system via the electric actuator, and the steering operation of the vehicle is controlled by the driving assistance system via the electric power steering device. For actuators and control circuits that are responsible for such autonomous driving, a redundant system is required in such a way that the function can be maintained by the other when one fails.

[0026] For example, the electric power steering device has two motor units and two motor drive control circuit units that are redundant with each other. In this case, one motor unit and the corresponding drive control circuit unit are equivalent to one automatic driving electric load included in the load A group 21, and the other motor unit and the corresponding drive control circuit unit are equivalent to another automatic driving electric load included in the load B group 22.

[0027] The power supply system of one embodiment has two secondary batteries for temporarily storing the power generated by the AC generator 2. That is, it has a lead-acid battery 6 and a lithium-ion battery 7 which are equivalent to the second power storage device in the technical solution. The lead-acid battery 6 is a so-called 12V battery that is mostly used as an on-board battery of a car, and a battery of appropriate capacity is used considering the overall load group A 21 and the load group B 22. The lithium-ion battery 7 is a backup power supply mainly used for ensuring power for the automatic driving electrical load of the load group B 22, for example, a battery with a relatively smaller capacity than the capacity of the lead-acid battery 6 is used. In addition, generally, lithium-ion batteries have a smaller internal resistance than lead-acid batteries and excellent charging and discharging characteristics. The lithium-ion battery 7 has a voltage equivalent to that of the lead-acid battery 6 by adjusting the number of battery cells.

[0028] The lead-acid battery 6 has a built-in current / voltage sensor 8 for detecting the current and voltage of the lead-acid battery 6. The current / voltage sensor 8 detects the current and voltage during charging and discharging, and estimates the charge state (SOC) of the lead-acid battery 6 based on the above parameters.

[0029] The lithium-ion battery 7 has a built-in battery management system (BMS) 9 and a LiB relay 10 in a battery pack containing battery cells. The battery management system 9 detects the voltage and current of the battery cell unit, suppresses overcharging and overdischarging, and performs equalization of the battery cell voltage, calculation of the charge level (SOC), etc. In addition, the battery cell temperature is detected and overcurrent is monitored. For example, the LiB relay 10 is cut off at abnormally high temperature or overcurrent to protect the lithium-ion battery 7. In addition, the LiB relay 10 that serves as a protection circuit is composed of a relay with contacts.

[0030] The lead-acid battery 6 is connected to the AC generator 2, the starting motor 5, and the load group A 21 as the main circuit 11. The lithium-ion battery 7 with the built-in LiB relay 10 is connected to the load group B 22 as the backup circuit 12. In addition, the main circuit 11 and the backup circuit 12 are connected to each other via a circuit disconnection switch 13 (equivalent to the disconnection device in the technical solution). The circuit disconnection switch 13 is composed of a semiconductor switch in consideration of responsiveness. Figure 1 As shown, the circuit cutoff switch 13 is disposed between the lead-acid battery 6 for supplying electric power to the starter motor 5 and the load group B 22 mainly composed of electric loads for autonomous driving.

[0031] The disconnection of the circuit cutoff switch 13 and the disconnection of the LiB relay 10 are controlled by the controller 14 in charge of power supply control. In addition, the controller 14 controls the voltage and power generation of the AC generator 2, and controls the starting motor 5 when starting the engine 1 (initial start and restart after idling stop). In addition, the controller 14 can be composed of multiple modules or controllers.

[0032] The controller 14 appropriately performs fuel efficiency improvement control for reducing the driving energy of the generator, i.e., the alternator 2, in order to reduce the fuel consumption of the vehicle. The fuel efficiency improvement control includes idle stop control for stopping the engine 1 when the vehicle temporarily stops at an intersection, etc., and power generation control for substantially reducing the power generation of the alternator 2 to zero. In the following specific embodiments, the idle stop control is used as an example for explanation, but the power generation control can also be performed in the same manner as the idle stop control.

[0033] Figure 2 It is used for Figure 1 The following is an explanatory diagram for explaining the basic operation of the power supply system of one embodiment shown in FIG. Figure 2 In the following explanatory diagrams, the flow of the main currents is indicated by arrows. Figure 2 (a) shows the state where the ignition switch of the vehicle is turned off (OFF). In this ignition switch off state, the circuit cutoff switch 13 is controlled to be turned on (ON) (conduction state), and the LiB relay 10 is turned off (cutoff state). In this ignition switch off state, most electrical loads do not need power, but some electrical loads also consume power while waiting, so-called waiting current flows in the circuit. Figure 2 As shown by arrows in (a), the lead-acid battery 6 supplies the power required for the waiting time to both the load group A 21 and the load group B 22. Since the LiB relay 10 is in the cut-off state, the charge amount of the lithium-ion battery 7 does not decrease.

[0034] If the ignition switch is on, Figure 2 As shown by arrows in (b), the lead-acid battery 6 supplies power to the starter motor 5, cranking and starting (initial start) the engine 1. During cranking, the LiB relay 10 remains in the OFF state, and the power of the lithium-ion battery 7 is not consumed.

[0035] If the startup is complete, Figure 2 As shown in (c), the LiB relay 10 is turned on. Therefore, as shown by the arrow, both the lead-acid battery 6 and the lithium-ion battery 7 are charged by the power generation of the AC generator 2. The voltage is controlled so that the charge amount of the lead-acid battery 6, which is reduced by the power consumption when the ignition switch is turned off and the crankshaft is rotated, and the charge amount of the lithium-ion battery 7, which is slightly reduced by natural discharge, are quickly restored.

[0036] Figure 2(d) shows a normal driving state in which the lead-acid battery 6 and the lithium-ion battery 7 are fully charged. The circuit cutoff switch 13 and the LiB relay 10 are both in the on state. In this state, power is basically supplied from the alternator 2 to the load group A 21 and the load group B 22. In this state, fuel efficiency improvement control, such as idling stop control, is appropriately executed.

[0037] If from Figure 2 The control state (d) stops the vehicle and turns off the ignition switch, then the LiB relay 10 is disconnected and the vehicle is restored to Figure 2 (a) Status.

[0038] Next, refer to Figure 3 The timing diagram and Figure 4 The operation explanation diagram of FIG. 1 is used to explain the power supply control during the idling stop control.

[0039] The idle stop control is an effective method for reducing the fuel consumption of the vehicle. When several idle stop conditions are met at the same time (so-called AND conditions), such as the vehicle speed is approximately 0, after the warm-up is completed, the accelerator pedal is turned off, the brake pedal is turned on, and the charge amount of the lead-acid battery 6 and the lithium-ion battery 7 is greater than or equal to a specified level (LABSOC2 and LiBSOC1 described later), the engine 1 is automatically stopped. Then, when any one of several restart conditions such as the brake pedal is turned off and a start request from the air conditioner is met (so-called OR conditions), the engine 1 is automatically restarted.

[0040] Figure 4 This is an illustration for explaining the operation of the idle stop control. Figure 2 (d) The idle stop condition is satisfied and the idle stop control is started. Figure 4 (a) shows that the circuit cutoff switch 13 is turned off. The LiB relay 10 remains in the on state. In the idle stop control, the engine 1 stops and the power generation of the AC generator 2 stops, so the load group A 21 is supplied with power from the lead-acid battery 6, and the load group B 22 is supplied with power from the lithium-ion battery 7. Thus, power is reliably supplied to the two mutually redundant automatic driving electric loads included in the load group A 21 and the load group B 22.

[0041] Furthermore, it is preferable that one of the idling stop conditions includes that the LiB relay 10 is actually in the on state. That is, it is preferable not to start the idling stop control in a state where electric power cannot be supplied from the lithium ion battery 7 to the load group B 22 .

[0042] Next, when the restart condition is met and restart is performed, Figure 4As shown in (b), power is supplied from the lead-acid battery 6 to the starting motor 5, and cranking for restarting is performed. At this time, the circuit cutoff switch 13 is kept off and the LiB relay 10 is turned on. Therefore, the following state is in which the lithium-ion battery 7 continues to supply power to the automatic driving power load of the load group B 22, and on the other hand, the lithium-ion battery 7 is disconnected from the starting motor 5 and the lead-acid battery 6, and no power flows from the lithium-ion battery 7 to the main circuit 11 side. The lithium-ion battery 7 has a smaller internal resistance than the lead-acid battery 6, so if both the lead-acid battery 6 and the lithium-ion battery 7 are connected to the starting motor 5, the power on the lithium-ion battery 7 side will be consumed first. The circuit cutoff switch 13 is disconnected without affecting the lithium-ion battery 7 during restarting.

[0043] Furthermore, in the above-described embodiment, the circuit cutoff switch 13 is substantially controlled to be turned off at the same time as the idling stop control is started for restarting. Therefore, when there is a restart request, there is no lag time for switching the circuit cutoff switch 13 to be turned off, and the restart can be started quickly. In addition, there is no concern that power will flow out from the lithium-ion battery 7 to the load group A 21 during the idling stop control.

[0044] Figure 4 (c) shows the control state immediately after restarting. After restarting, the lead-acid battery 6 is charged first with priority. Therefore, the circuit cutoff switch 13 is kept disconnected for a predetermined period after restarting. The lead-acid battery 6 is charged by the power generated by the AC generator 2. During this period, the load group B 22 receives power supply from the lithium-ion battery 7. This takes into account the consumption of power of the lead-acid battery 6 due to the crankshaft rotation at restarting, the internal resistance of the lead-acid battery 6 being greater than the internal resistance of the lithium-ion battery 7, and the like.

[0045] Then, if Figure 4 As shown in (d), the circuit cutoff switch 13 is controlled to be on, and charging of both the lead-acid battery 6 and the lithium-ion battery 7 is started.

[0046] Figure 3 1 is a timing chart showing power supply control during idle stop control. In this example, idle stop control is performed twice. The period marked as "IS" in the top column (a) is the period of idle stop control (same as Figure 4 (a) corresponds to the period of "LAB charging" which is the priority charging period of the lead-acid battery 6 (corresponding to Figure 4 (c) corresponds to the period of “LiB+LAB charging”, which is the period of charging of both the lithium-ion battery 7 and the lead-acid battery 6 (corresponding to Figure 4 (d) Corresponding to the above. As described above, after the idling stop control is completed, the lead-acid battery 6 is charged preferentially, and then both the lithium-ion battery 7 and the lead-acid battery 6 are charged.

[0047] The column (b) shows the change of the charge amount (SOC) of the lead-acid battery 6 (abbreviated as LAB in the figure). LABSOC1 is the target SOC of the lead-acid battery 6 for ending the priority charging of the lead-acid battery 6 after the restart. LABSOC2 is the idle stop prohibition SOC of the lead-acid battery 6, which is one of the idle stop conditions. LABSOC2 is set to a value lower than LABSOC1. If the charge amount (SOC) of the lead-acid battery 6 is lower than LABSOC2, the idle stop control is prohibited, and then until it returns to LABSOC1, it is in a state where the idle stop control is prohibited as a so-called hysteresis. The charge amount of the lead-acid battery 6 decreases due to the power consumption of the load A group 21 during the idle stop control and the crankshaft rotation at the time of restart, and increases during the subsequent charging period. In the illustrated example, the priority charging period of the lead-acid battery 6 after the first idle stop control ends at time t3 because the charge amount of the lead-acid battery 6 reaches LABSOC1. That is, it is considered that the prescribed period for the priority charging of the lead-acid battery 6 has passed because the charging target LABSOC1 has been reached.

[0048] The first idle stop control in the timing chart ends at time t2, for example, when the driver releases the brake pedal, etc. In contrast, the second idle stop control ends at time t5, when the charge amount of the lead-acid battery 6 decreases to LABSOC2, which is the idle stop prohibition SOC.

[0049] Column (c) shows the change of the charge level (SOC) of the lithium-ion battery 7 (abbreviated as LiB in the figure). LiBSOC1 is the idle stop prohibition SOC at which the idle stop control is prohibited when it is less than or equal to this value. In addition, this LiBSOC1 is also the lower limit SOC at which the lithium-ion battery 7 should be charged. During the period of priority charging of the lead-acid battery 6 after the idle stop control, if the charge level of the lithium-ion battery 7 decreases to LiBSOC1, the charging of both the lithium-ion battery 7 and the lead-acid battery 6 will be started. LiBSOC2 is the automatic driving warning SOC that becomes the lower limit of the power required for the automatic driving function to be output for the automatic driving power load of the load group B 22. If the charge level of the lithium-ion battery 7 is lower than this LiBSOC2 during the implementation of the automatic driving, an alarm (voice, screen display, etc.) is issued to the driver to urge the switch from automatic driving to manual driving. LiBSOC1 is set to a value higher than LiBSOC2 in a manner with an appropriate margin until the alarm is issued. The charge amount of the lithium ion battery 7 decreases due to the power consumption of the load group B 22 during the idle stop control and the priority charging period of the lead-acid battery 6 that continues to the control, and increases during the charging period of both the lithium ion battery 7 and the lead-acid battery 6. In the illustrated example, the priority charging period of the lead-acid battery 6 after the second idle stop control ends at time t6 because the charge amount of the lithium ion battery 7 decreases to LiBSOC1. That is, here, it is considered that the prescribed period for the priority charging of the lead-acid battery 6 has passed because it has decreased to LiBSOC1.

[0050] In addition, the duration of the prescribed period for preferential charging of the lead-acid battery 6 can be prescribed. In this case, preferential charging of the lead-acid battery 6 ends after a constant time has passed, and charging of both the lithium-ion battery 7 and the lead-acid battery 6 begins.

[0051] The column (d) indicates whether the alternator 2 (abbreviated as ALT in the figure) is in a power generation state (Generate) or a non-power generation state (Not Generate). Power generation is stopped during the idling stop control.

[0052] The column (e) shows the open / closed state of the circuit cutoff switch 13 (abbreviated as HNS in the drawing). The circuit cutoff switch 13 is opened (disconnected) during the idle stop control and the priority charging period of the lead-acid battery 6, and is closed (connected) during the charging period of both the lithium-ion battery 7 and the lead-acid battery 6. The column (f) shows the open / closed state of the LiB relay 10. The LiB relay 10 maintains the closed state (connected) during the period of the timing diagram in the drawing.

[0053] Thus, in the above-mentioned embodiment, the idle stop control is appropriately performed as a fuel efficiency improvement control, but the temperature of the lithium-ion battery 7 is easily increased by repeatedly performing the idle stop control. If the temperature of the lithium-ion battery 7 is excessively increased, the reliability of the power supply to the electric load for autonomous driving is reduced. Therefore, in the above-mentioned embodiment, when the temperature of the lithium-ion battery 7 detected by the battery management system 9 (such as a representative temperature such as the battery cell temperature or the atmosphere temperature in the battery pack) is greater than or equal to the prescribed idle stop prohibition temperature T1, the controller 14 prohibits the idle stop control. In this sense, the temperature of the lithium-ion battery 7 being less than the idle stop prohibition temperature T1 can be referred to as one of the idle stop conditions as an AND condition. In this way, the temperature increase of the lithium-ion battery 7 is suppressed by prohibiting the idle stop control.

[0054] When the temperature of the lithium ion battery 7 is equal to or higher than the idle stop prohibition temperature T1 during the idle stop control, the idle stop control is terminated and restart is performed. In this sense, being equal to or higher than the idle stop prohibition temperature T1 can be regarded as one of the restart conditions as an OR condition.

[0055] Restart is the same as usual, as mentioned above Figure 4 (b), when the circuit cutoff switch 13 is turned off and the LiB relay 10 is turned on, power is supplied from the lead-acid battery 6 to the starter motor 5 to perform cranking. Figure 4 As shown in (c), in a state where the circuit cutoff switch 13 is OFF and the LiB relay 10 is ON, the lead-acid battery 6 is preferentially charged.

[0056] If the charge level of the lead-acid battery 6 reaches LABSOC1 or the charge level of the lithium-ion battery 7 decreases to LiBSOC1 due to the priority charge of the lead-acid battery 6 as described above, the priority charge of the lead-acid battery 6 is terminated and the circuit cut-off switch 13 is turned off. Figure 4 (d) is turned on. However, here, during the period when the temperature of the lithium-ion battery 7 is greater than or equal to the idling stop prohibition temperature T1, the voltage of the alternator 2 is controlled to be low so that the lithium-ion battery 7 is not charged. By limiting the charging of the lithium-ion battery 7 in this way, the temperature increase of the lithium-ion battery 7 is suppressed. Electric power is supplied from the alternator 2 to the load group A 21 and the load group B 22, which each include the electric loads for autonomous driving.

[0057] Regarding the temperature of the lithium-ion battery 7, an automatic driving prohibition temperature T2 (equivalent to the second specified temperature in the technical solution) is specified to prohibit automatic driving from the perspective of power supply reliability. If the temperature of the lithium-ion battery 7 is greater than or equal to the automatic driving prohibition temperature T2, automatic driving is prohibited. The idling stop prohibition temperature T1 is set to be lower than the automatic driving prohibition temperature T2, and the temperature of the lithium-ion battery 7 is prevented from rising to the automatic driving prohibition temperature T2 by executing the idling stop control. In addition, if the temperature of the lithium-ion battery 7 reaches a higher protection circuit operating temperature T3, the LiB relay 10 performs a disconnection operation based on the detection of the battery management system 9 to protect the battery cells of the lithium-ion battery 7. The automatic driving prohibition temperature T2 is set to be lower than the protection circuit operating temperature T3, and the automatic driving is terminated in advance. In addition, it is preferred to issue an appropriate alarm (voice, screen display, etc.) when the automatic driving is prohibited when the temperature is greater than or equal to the automatic driving prohibition temperature T2.

[0058] On the other hand, if an overcurrent flows through the lithium-ion battery 7, the battery cell further deteriorates. Therefore, the battery management system 9 monitors the current flowing through the battery cell of the lithium-ion battery 7, and if it exceeds the specified current resistance value, the LiB relay 10 performs a disconnection operation to protect the battery cell. The maximum power generation current value of the AC generator 2 is set to be lower than the current resistance value of the lithium-ion battery 7. As a result, for example, an excessive current will not flow through the lithium-ion battery 7 due to the regenerative action of the AC generator 2 when the vehicle decelerates. In addition, the current resistance value of the circuit disconnection switch 13 composed of a semiconductor switch is relatively high compared to the current resistance value of the lithium-ion battery 7 that causes the LiB relay 10 to perform a disconnection operation. Therefore, when a large current flows from the main circuit 11 side toward the lithium-ion battery 7, the LiB relay 10 performs a disconnection operation before the circuit disconnection switch 13 is damaged, thereby protecting the circuit disconnection switch 13.

[0059] An embodiment of the present invention has been described in detail above, but the present invention is not limited to the above embodiment, and various changes can be made. For example, in the above embodiment, the electric load for autonomous driving is divided into two redundant electric loads, but the present invention is not limited to application to such redundant systems. In addition, in the above embodiment, a lead-acid battery 6 is used as the second power storage device, but it can also be any other suitable secondary battery, capacitor or other structure. In addition, it can also be a structure without a second power storage device. In addition, as a generator, it can also be an electric generator that can realize the crankshaft rotation of the engine 1.

[0060] In the above embodiment, the idle stop control is described as the fuel efficiency improvement control, but it can also be a control that makes the power generation of the AC generator 2 substantially zero (that is, stops the power generation drive). In this case, except that it is not necessary to restart, the same processing can be performed as in the case of the idle stop control of the above embodiment.

[0061] Of course, both idling stop control and power generation control can be performed as fuel efficiency improvement control. In this case, the prescribed temperature for prohibiting fuel efficiency improvement control can be the same temperature for idling stop control and power generation control, or different temperatures considering the degree of temperature rise.

Claims

1. A method for controlling a vehicle, wherein: The vehicle has: engine; a generator driven by the engine to generate electricity; and The lithium-ion battery is charged by the electric power generated by the generator and supplies the electric power required for the autonomous driving of the vehicle to the autonomous driving electric load. When a predetermined condition is satisfied, a fuel efficiency improvement control for reducing the driving energy of the generator is executed. When the temperature of the lithium-ion battery is greater than or equal to a predetermined temperature, the fuel efficiency improvement control is prohibited.

2. The vehicle control method according to claim 1, wherein: When the temperature of the lithium-ion battery is greater than or equal to a second predetermined temperature, the automatic driving of the vehicle is prohibited. The predetermined temperature is lower than the second predetermined temperature.

3. The vehicle control method according to claim 1, wherein: The fuel efficiency improvement control is a control for stopping the engine from driving the generator to generate electric power.

4. The vehicle control method according to claim 1, wherein: The fuel efficiency improvement control is an idle stop control for stopping the engine when the vehicle stops.

5. The vehicle control method according to claim 1, wherein: When the fuel efficiency improvement control is prohibited, the electric power generated by the generator is supplied to the automatic driving electric load.

6. The vehicle control method according to claim 5, wherein: When the fuel efficiency improvement control is prohibited, the voltage is controlled to be such that the lithium ion battery is not substantially charged.

7. The vehicle control method according to claim 1, wherein: The vehicle has a disconnecting device disposed between the generator and the lithium-ion battery. The current resistance value of the disconnecting and connecting device is set to be higher than the current resistance value of the lithium ion battery.

8. The vehicle control method according to claim 7, wherein: The maximum power generation current value of the generator is set to be lower than the current withstand value of the lithium ion battery.

9. The vehicle control method according to claim 4, wherein: The vehicle further includes a second power storage device charged with the electric power generated by the generator. The autonomous driving electrical load includes a first electrical load and a second electrical load that form a redundant system with each other. The vehicle further comprises a disconnecting device disposed between the generator and the lithium-ion battery. During the idle stop control, the disconnecting device is controlled to be in a disconnected state. In the disconnecting state of the disconnecting and connecting device, the first electric load receives electric power from the lithium-ion battery, and the second electric load receives electric power from the second power storage device.

10. The vehicle control method according to claim 9, wherein: The second power storage device is a lead-acid battery.

11. A vehicle control device, wherein: The vehicle has: engine; A generator, which is driven by the above engine to generate electricity; a lithium-ion battery that is charged by the electric power generated by the generator and supplies the electric power required for the autonomous driving of the vehicle to the autonomous driving electric load; as well as Controller, The controller executes fuel efficiency improvement control for reducing driving energy of the generator when a predetermined condition is satisfied. When the temperature of the lithium-ion battery is greater than or equal to a predetermined temperature, the fuel efficiency improvement control is prohibited.

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