Vehicle control device

Abstract

To increase a possibility that an engine is successfully started up.SOLUTION: When an engine is failed to be started up through both cranking using a first start-up device having a motor and a high-voltage power source device and cranking using a second start-up device having a starter motor and a low-voltage power source device supplying electric power to plural types of electric loads, a vehicle control device re-implements the cranking using the second start-up device and thereby increasing a possibility of successful engine start-up by retrying cranking using a second start-up device, that may cause a failure of the engine start-up due to tentative overlap of action of the starter motor with action of the electric load. Thus, the vehicle control device can increase the possibility of the successful engine start-up.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a control device for a vehicle equipped with an engine and a plurality of starting devices. [Background technology]

[0002] A control device for a vehicle including an engine, two power supply devices, and a cranking device operated by power supply from each power supply device is well known. For example, a vehicle power supply system described in Patent Document 1 is one such device. Patent Document 1 discloses that when restarting the engine, a starter as a cranking device is operated by power supply from a secondary battery as a power supply device, and when restarting the engine after a failed restart attempt, if the environmental temperature is lower than a certain value, the starter is operated by power supply from a lead storage battery as a power supply device. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2015 / 015743 Summary of the Invention [Problem to be solved by the invention]

[0004] However, there are cases where the engine fails to be restarted after a previous restart has failed. In this case, the engine fails to be started regardless of whether the power is supplied from the secondary battery or the lead-acid battery. Therefore, when attempting to start the engine again, it is unclear from which battery the power should be supplied. This may result in another failure to start the engine.

[0005] The present invention has been made in light of the above circumstances, and an object of the present invention is to provide a vehicle control device that can increase the probability of successful engine start-up. [Means for solving the problem]

[0006] The gist of a first invention is a control device for a vehicle including: (a) an engine; a first starting device having an engine, an electric motor connected to the engine so as to be capable of transmitting power, and a high-voltage power supply device that supplies and receives electric power to the electric motor, and that cranks the engine using the electric motor; a second starting device having a starter motor arranged to be capable of rotating the engine, and a low-voltage power supply device arranged to be chargeable by the high-voltage power supply device and that supplies electric power to the starter motor, and that cranks the engine using the starter motor; and a plurality of types of electric loads that are temporarily operated by electric power supplied from the low-voltage power supply device; (b) at the time of starting the engine, the cranking using the first starting device is preferentially performed over the cranking using the second starting device, and if the starting by the cranking using the first starting device fails, the cranking using the second starting device is performed, and if the starting by the cranking using the first starting device fails and the starting by the cranking using the second starting device also fails, the first starting device Instead of performing the cranking using The cranking control unit includes a start control unit that executes the cranking using the second starting device.

[0007] A second aspect of the present invention is a vehicle control device according to the first aspect of the present invention, The cranking using the second starting device serves as a backup function when starting the engine, The start control unit permits idling stop control to temporarily stop operation of the engine when the start using the second starting device can be guaranteed, and prohibits the idling stop control when the start using the second starting device cannot be guaranteed.

[0008] Further, a third invention is directed to a vehicle control device according to the second invention, wherein, when the starting using the second starting device is successful, the starting control unit determines whether or not the starting using the second starting device can be guaranteed based on whether or not the output voltage of the low-voltage power supply device during the cranking transition using the second starting device is equal to or higher than a predetermined voltage.

[0009] Further, a fourth invention is a vehicle control device as described in the second or third invention, wherein when the vehicle is in a predetermined extremely low temperature environment where it is determined that the electric motor cannot be properly controlled when starting the engine, the start control unit performs the cranking using the second starting device instead of the cranking using the first starting device.

[0010] Further, a fifth invention is that in the vehicle control device described in the second or third invention, the idling stop control includes at least one of control for temporarily stopping the operating engine while the vehicle is running or stopped, and control for causing the engine to wait in a stopped state without starting it when the vehicle has not yet started after being powered on. Effect of the Invention

[0011] According to the first aspect of the present invention, when starting an engine, cranking using a first starting device having an electric motor and a high-voltage power supply device is preferentially performed over cranking using a second starting device having a starter motor and a low-voltage power supply device that supplies power to a plurality of types of electric loads. If starting using the first starting device fails, cranking using the second starting device is performed. If starting using the first starting device fails and starting using the second starting device also fails, cranking using the first starting device is performed. Cranking using theSince cranking is performed using the second starting device, there is a possibility that starting will be successful by reattempting cranking using the second starting device, which may have failed due to a temporary overlap between the operation of the starter motor and the operation of the electrical load, thereby increasing the probability of successful engine start.

[0012] According to the second aspect of the present invention, Cranking using the second starting device serves as a backup function when starting the engine. When starting using the second starting device can be guaranteed, idling stop control is permitted, and when starting using the second starting device cannot be guaranteed, idling stop control is prohibited, thereby avoiding or suppressing failure to start the engine after releasing the idling stop control.

[0013] Furthermore, according to the third aspect of the invention, if starting using the second starting device is successful, it is determined whether starting using the second starting device can be guaranteed based on whether the output voltage of the low-voltage power supply device during the cranking transition using the second starting device is equal to or higher than a predetermined voltage. Therefore, the state of the low-voltage power supply device can be determined by the voltage of the low-voltage power supply device during cranking using the second starting device, and it is possible to avoid the prohibition of idling stop control, i.e., the loss of opportunity, due to the state of the low-voltage power supply being uncertain.

[0014] Furthermore, according to the fourth aspect of the present invention, when the vehicle is in a predetermined extremely low temperature environment where it is determined that the electric motor cannot be properly controlled when starting the engine, cranking using the second starting device is performed instead of cranking using the first starting device, thereby avoiding or suppressing failure to start the engine.

[0015] Furthermore, according to the fifth aspect of the present invention, the idling stop control includes at least one of control for temporarily stopping an operating engine while the vehicle is running or stopped, and control for causing the engine to wait in a stopped state without starting it when the vehicle has not yet started after being powered on, thereby improving energy efficiency. [Brief description of the drawings]

[0016] [Figure 1] 1 is a diagram illustrating a schematic configuration of a vehicle to which the present invention is applied, and is also a diagram illustrating main parts of control functions and a control system for various controls in the vehicle. [Diagram 2] FIG. 11 is a diagram showing an example of a starter starting voltage when the engine is started using a second starting device (starter motor). [Diagram 3] 4 is a flowchart illustrating a main part of the control operation of the electronic control device, and is a flowchart illustrating the control operation for increasing the probability of successful starting of the engine. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. EXAMPLES

[0018] Fig. 1 is a diagram for explaining a schematic configuration of a vehicle 10 to which the present invention is applied, and also a diagram for explaining main parts of control functions and a control system for various controls in the vehicle 10. In Fig. 1, the vehicle 10 includes an engine 12, an automatic transmission 14, a first starting device 16, a second starting device 18, a DC-DC converter 20, an electric load 22, a start button 24, etc.

[0019] The engine 12 is a power source of the vehicle 10. The engine 12 is a known internal combustion engine such as a gasoline engine or a diesel engine. An electronic control device 70 (described later) controls engine control devices (not shown) including a throttle actuator, a fuel injection device, an ignition device, etc., to control engine torque Te, which is the output torque of the engine 12.

[0020] The automatic transmission 14 may be, for example, a known planetary gear type automatic transmission, a known synchronous mesh type parallel two-shaft automatic transmission including a known DCT (Dual Clutch Transmission), a known belt type continuously variable transmission, a known electric continuously variable transmission, etc. The automatic transmission 14 is connected to the engine 12 so as to be capable of transmitting power, and transmits power from the engine 12 to driving wheels (not shown).

[0021] The first starting device 16 includes an electric motor MG and a high-voltage battery 26. The electric motor MG is a motor generator that functions as a motor that generates mechanical power from electric power and as a generator that generates electric power from mechanical power. The electric motor MG is connected to the high-voltage battery 26 via an inverter that is integral with the electric motor MG. The high-voltage battery 26 is an electricity storage device that supplies electric power to the electric motor MG. The inverter of the electric motor MG is controlled by an electronic control device 70, which will be described later, to control the MG torque Tm, which is the torque of the electric motor MG. The electric motor MG is driven by electric power supplied from the high-voltage battery 26 during power running. The electric motor MG supplies the generated electric power to the high-voltage battery 26 during regeneration.

[0022] The electric motor MG is connected to the crankshaft 12a of the engine 12 via a drive belt 28 provided on the vehicle 10 so as to be capable of transmitting power. Therefore, the electric motor MG has a function of rotating and driving, i.e. cranking, the engine 12 by power running operation when the engine 12 is stopped. In other words, the first starting device 16 has a function of cranking the engine 12 using the electric motor MG. Moreover, the electric motor MG has a function of assisting the power of the engine 12 by power running operation when the engine 12 is operating. Moreover, the electric motor MG has a function of generating electric power from the power of the engine 12 by regenerative operation when the engine 12 is operating. Moreover, the electric motor MG has a function of generating electric power from the driven force input from the drive wheels by regenerative operation when the vehicle is decelerating.

[0023] A / C compressor 30, which is an air conditioner compressor provided in the vehicle 10, a power steering pump (not shown), a water pump (not shown), and other accessories, as well as the electric motor MG, are operatively connected to the crankshaft 12a of the engine 12 via a drive belt 28, and are each driven by the engine 12. When the electric motor MG, the A / C compressor 30, and other accessories are connected to the crankshaft 12a via, for example, an electromagnetic clutch (not shown), the accessories such as the A / C compressor 30 are driven only by the operation of the electric motor MG when the electromagnetic clutch is released. In other words, the electric motor MG has a function of driving the accessories such as the A / C compressor 30 during execution of an idling stop control CTspidl that temporarily stops the operation of the engine 12.

[0024] The idling stop control CTspidl is an automatic engine stop control that automatically stops the operation of the engine 12 by, for example, cutting fuel, and automatically restarts and restores the engine 12 when a restoration condition, such as releasing the brake pedal or depressing the accelerator pedal, is satisfied. The idling stop control CTspidl includes a normal idling stop control S&S (Stop and Start) that temporarily stops the operation of the operating engine 12 while the vehicle 10 is running or stopped, and a non-start idling stop control FIS (First Idling Stop) that keeps the engine 12 in a stopped state without starting it when the vehicle 10 has not yet started after the power is turned on. The normal idling stop control S&S is a post-start idling stop control. The power-on state of the vehicle 10 is an ignition-on (= "IG-ON") state, which will be described later.

[0025] The second starting device 18 includes a starter motor 32, a low-voltage battery 34, and the like. The starter motor 32 is provided so as to be capable of rotating and driving the engine 12. The starter motor 32 is driven by electric power supplied from the low-voltage battery 34. The starter motor 32 is a starting motor used to start the engine 12. In other words, the starter motor 32 is a dedicated motor for rotating and driving, i.e., cranking, the engine 12 when starting the engine 12. The second starting device 18 has a function of cranking the engine 12 using the starter motor 32.

[0026] The DCDC converter 20 is connected to the high-voltage battery 26. The DCDC converter 20 reduces the voltage of the high-voltage battery 26 to charge the low-voltage battery 34 and supply power to the electric load 22. The low-voltage battery 34 is connected to the DCDC converter 20 and is charged by the DCDC converter 20 using the power supplied from the high-voltage battery 26 as a source. The low-voltage battery 34 is a low-voltage power supply device that is provided so as to be chargeable by the high-voltage battery 26 and supplies power to the starter motor 32. The high-voltage battery 26 is a high-voltage battery that stores a voltage higher than that of the low-voltage battery 34, and is a high-voltage power supply device that is provided so as to be able to charge the low-voltage battery 34. The high-voltage battery 26 is a secondary battery such as a lithium-ion battery or a nickel-metal hydride battery. The low-voltage battery 34 is a secondary battery such as a lead-acid battery.

[0027] The electric loads 22 are various kinds of electric devices that operate with power supplied from the low-voltage battery 34, etc. The electric loads 22 are, for example, wipers, blower motors, navigation systems, etc.

[0028] The start button 24 is a power switch operated by the driver to switch the state of power supply in the vehicle 10, i.e., the state of the vehicle power supply. The start button 24 is, for example, a momentary push button switch, and is pressed by the driver to the switch-on position. Every time the start button 24 is pressed to the switch-on position, it outputs a power switch signal PSon corresponding to the switch-on position to the electronic control device 70, which will be described later. The electronic control device 70 detects the operation of the start button 24 by the driver based on the power switch signal PSon.

[0029] The vehicle power supply state is, for example, an off state (= "OFF"), an accessory on state (= "ACC"), and an ignition on state (= "IG-ON"). The "OFF" state is, for example, a power supply state for disabling the vehicle from running and disabling some functions not related to the vehicle running. The "ACC" state is, for example, a power supply state for turning off a combination meter (not shown) to disable the vehicle from running but enabling some functions not related to the vehicle running. The "IG-ON" state is, for example, a power supply state for turning on the combination meter to enable the vehicle to run.

[0030] The vehicle 10 further includes an electronic control device 70 including a control device for the vehicle 10. The electronic control device 70 includes a so-called microcomputer equipped with, for example, a CPU, RAM, ROM, an input / output interface, and the like, and the CPU executes various controls of the vehicle 10 by performing signal processing according to a program previously stored in the ROM while utilizing the temporary storage function of the RAM. The electronic control device 70 includes various computers for engine control, transmission control, etc. as necessary.

[0031] The electronic control device 70 is supplied with various signals based on detection values ​​by various sensors provided in the vehicle 10 (e.g., the DCDC converter 20, the start button 24, the engine rotation speed sensor 50, the MG rotation speed sensor 52, the vehicle speed sensor 54, the accelerator opening sensor 56, the throttle valve opening sensor 58, the brake switch 60, etc.) (e.g., the DCDC power supply voltage VLdc, the power switch signal PSon, the engine rotation speed Ne which is the rotation speed of the engine 12, the MG rotation speed Nm which is the rotation speed of the electric motor MG, the vehicle speed V, the accelerator opening θacc which is the driver's accelerator operation amount which indicates the magnitude of the driver's acceleration operation, the throttle valve opening θth which is the opening of the electronic throttle valve, the brake on signal Bon which is a signal indicating a state in which the brake pedal for activating the wheel brakes is being operated by the driver, etc.).

[0032] The DCDC power supply voltage VLdc is the output voltage of the DCDC converter 20 supplied to the low-voltage battery 34 after the voltage of the high-voltage battery 26 is stepped down, and represents the output voltage of the low-voltage battery 34. The DCDC converter 20 includes, for example, a microcomputer, and has a function of detecting the DCDC power supply voltage VLdc. The DCDC converter 20 is supplied with a low-voltage battery temperature THlowb, which is the temperature of the low-voltage battery 34, and a low-voltage battery charge / discharge current Ilowb, which is the charge / discharge current of the low-voltage battery 34, as signals based on the detection value by the low-voltage battery sensor 62 provided in the vehicle 10.

[0033] The electronic control device 70 outputs various command signals (e.g., an engine control command signal Se for controlling the engine 12, a transmission control command signal Sat for controlling the automatic transmission 14, an MG control command signal Sm for controlling the electric motor MG, a DCDC control command signal Sdc for controlling the DCDC converter 20, a starter control command signal Sst for controlling the starter motor 32, etc.) to each device (e.g., the engine 12, the automatic transmission 14, the electric motor MG, the DCDC converter 20, the starter motor 32, etc.) provided in the vehicle 10.

[0034] In order to realize various controls in the vehicle 10, the electronic control unit 70 includes an engine control means, i.e., an engine control section 72, a transmission control means, i.e., a transmission control section 74, and a starting control means, i.e., a starting control section 76.

[0035] The engine control unit 72 calculates a driving demand amount for the vehicle 10 by the driver, for example, by applying the accelerator opening θacc and the vehicle speed V to a driving demand amount map. The driving demand amount map is a relationship that is experimentally or design-wise determined and stored in advance, that is, a predetermined relationship. The driving demand amount is, for example, a required driving torque Trdem [Nm] at the driving wheels. As the driving demand amount, a required driving force Frdem [N] at the driving wheels or the like can also be used. The engine control unit 72 outputs an engine control command signal Se to the engine 12 to control the engine 12 to realize the required driving torque Trdem, taking into account a transmission loss, an auxiliary load, a gear ratio of the automatic transmission 14, and the like.

[0036] The transmission control unit 74 makes a shift determination for the automatic transmission 14 using, for example, a shift map, which is a predetermined relationship, and outputs a transmission control command signal Sat to the automatic transmission 14 to execute shift control of the automatic transmission 14 as necessary, that is, according to the result of the shift determination. The shift map is a predetermined relationship having a shift line for determining a shift of the automatic transmission 14 on a two-dimensional coordinate system having, for example, vehicle speed V and required driving torque Trdem as variables.

[0037] The start control unit 76 determines whether or not there is a request to start the engine 12, which switches the operating state, i.e., the control state, of the engine 12 from a stopped state to a running state. For example, the start control unit 76 determines whether or not there is a request to start the engine 12, based on whether or not the pre-start idling stop control FIS is executed when the state of the vehicle power supply is set to the "IG-ON" state, or whether or not the idling stop control CTspidl is released by, for example, turning off the brake-on signal Bon while the idling stop control CTspidl is being executed. In this embodiment, the request to start the engine 12 accompanying the release of the idling stop control CTspidl is called a restart request for the engine 12 when it is to be distinguished from the initial request to start the engine 12 accompanying the change of the vehicle power supply from "OFF" to "IG-ON".

[0038] When the start control unit 76 determines that there is a request to start the engine 12, it basically executes cranking using the first starting device 16. Specifically, when the start control unit 76 determines that there is a request to start the engine 12, it outputs an MG control command signal Sm to the electric motor MG to cause the electric motor MG to output a cranking torque Tcr. In conjunction with the cranking of the engine 12 by the electric motor MG, the start control unit 76 outputs an engine control command signal Se to the engine 12 to start fuel supply, engine ignition, and the like. The cranking torque Tcr is a predetermined torque required for cranking the engine 12 to increase the engine rotation speed Ne. The cranking torque Tcr is, for example, a constant torque that is determined in advance based on, for example, the specifications of the engine 12.

[0039] Here, when starting the engine 12, it becomes difficult to appropriately control the electric motor MG, for example, when the dischargeable power of the high-voltage battery 26 is set to be small or when it is difficult to supply electric power from the high-voltage battery 26. Therefore, for example, when the vehicle 10 is in a predetermined extremely low temperature environment where it is determined that the electric motor MG cannot be appropriately controlled, it may be difficult to start the engine 12 by cranking using the first starting device 16.

[0040] When starting the engine 12, if the vehicle 10 is in a predetermined extremely low temperature environment where it is determined that the electric motor MG cannot be appropriately controlled, the start control unit 76 performs cranking using the second starter 18 instead of cranking using the first starter 16. Specifically, when the start control unit 76 determines that there is a request to start the engine 12, if the vehicle 10 is in a predetermined extremely low temperature environment, the start control unit 76 outputs a starter control command signal Sst to the starter motor 32 to operate the starter motor 32, and cranks the engine 12 by the starter motor 32. In conjunction with the cranking of the engine 12 by the starter motor 32, the start control unit 76 outputs an engine control command signal Se to the engine 12 to start fuel supply, engine ignition, and the like. When the engine 12 is in a complete explosion state, the start control unit 76 cancels the starter control command signal Sst to stop cranking by the starter motor 32.

[0041] In this way, when starting the engine 12, the start control unit 76 preferentially executes cranking of the engine 12 using the first starting device 16 over cranking of the engine 12 using the second starting device 18. That is, when starting the engine 12 with the vehicle power source changing from "OFF" to "IG-ON" or with the release of the idling stop control CTspidl, cranking of the engine 12 using the first starting device 16 is executed preferentially. On the other hand, in an extremely low temperature environment, cranking of the engine 12 is executed using the second starting device 18 instead of the first starting device 16. Note that when starting the engine 12 for the first time with the vehicle power source changing from "OFF" to "IG-ON", the required cranking torque Tcr is likely to be large because the engine 12 has not yet been warmed up, so cranking of the engine 12 using the second starting device 18 may be executed.

[0042] However, when starting the engine 12, there is a possibility that starting using the first starting device 16 will fail. If starting using the first starting device 16 fails, the starting control unit 76 executes cranking of the engine 12 using the second starting device 18. In this way, cranking of the engine 12 using the second starting device 18 has a backup function when starting the engine 12.

[0043] There is a possibility that starting using the first starting device 16 will fail, and furthermore, starting using the second starting device 18 will also fail. The failure of starting using the second starting device 18 may be due to, for example, a temporary overlap between the operation of a large current load in the electric load 22 and the operation of the starter motor 32. Therefore, if cranking is performed again using the second starting device 18, there is a possibility that the engine 12 will be successfully started.

[0044] Therefore, when attempting to start the engine 12 by cranking the engine 12 using the first starting device 16 fails, if starting the engine 12 by cranking the engine 12 using the second starting device 18 also fails, the start control unit 76 will again crank the engine 12 using the second starting device 18.

[0045] Because cranking using the second starting device 18 works as a backup function, it is better not to execute the idling stop control CTspidl when starting of the engine 12 using the second starting device 18 cannot be guaranteed. The start control unit 76 permits the idling stop control CTspidl when starting of the engine 12 using the second starting device 18 can be guaranteed. On the other hand, the start control unit 76 prohibits the idling stop control CTspidl when starting of the engine 12 using the second starting device 18 cannot be guaranteed.

[0046] If the state of the low-voltage battery 34 is good, the start of the engine 12 using the second starting device 18 can be guaranteed. The state of the low-voltage battery 34 can be determined by the starter starting voltage VLst, which is the output voltage of the low-voltage battery 34 when the start of the engine 12 using the second starting device 18 is successful, that is, the DCDC power supply voltage VLdc. The starter starting voltage VLst is the DCDC power supply voltage VLdc during the transition of cranking the engine 12 using the second starting device 18 at the time when the start of the engine 12 using the second starting device 18 is successful. In other words, the starter starting voltage VLst is the DCDC power supply voltage VLdc at the time when the cranking of the engine 12 is completed due to, for example, the complete explosion of the engine 12.

[0047] FIG. 2 is a diagram showing an example of the starter starting voltage VLst when the engine 12 is started using the second starting device 18. In FIG. 2, time t1 indicates the time when the cranking of the engine 12 using the second starting device 18 is started, that is, the time when the drive of the starter motor 32 is started. When the drive of the starter motor 32 is started, the DCDC power supply voltage VLdc is lowered from the open circuit voltage OCV. When the start of the engine 12 is successful and the drive of the starter motor 32 is terminated, the DCDC power supply voltage VLdc is increased toward the open circuit voltage OCV (see time t2 and after). The DCDC power supply voltage VLdc at the time when the start of the engine 12 is successful, that is, the time when the drive of the starter motor 32 is terminated, is the starter starting voltage VLst (see time t2). The open circuit voltage OCV is the voltage between the terminals of the low voltage battery 34 when no load is applied to the low voltage battery 34.

[0048] 1, when the start of the engine 12 using the second starting device 18 is successful, the start control unit 76 determines whether or not the start of the engine 12 using the second starting device 18 can be guaranteed based on whether or not the starter start voltage VLst is equal to or higher than a predetermined voltage VLstf. The predetermined voltage VLstf is, for example, a predetermined threshold value for determining whether the state of the low-voltage battery 34 is good enough to guarantee the start of the engine 12 using the second starting device 18.

[0049] Specifically, when the starter start-up voltage VLst is equal to or higher than a predetermined voltage VLstf, the start-up control unit 76 maintains an idling stop prohibition flag, which is a prohibition flag for the idling stop control CTspidl, at OFF. On the other hand, when the starter start-up voltage VLst is lower than the predetermined voltage VLstf, the start-up control unit 76 switches the idling stop prohibition flag to ON. When the idling stop prohibition flag is ON, the idling stop control CTspidl is prohibited, and when the vehicle power supply is turned "OFF", the flag is turned OFF and is OFF by default.

[0050] In this way, the start control unit 76 determines the state of the low-voltage battery 34 based on the starter start voltage VLst, and permits or prohibits the next idling stop control CTspidl. In other words, when the state of the low-voltage battery 34 is unknown, the next idling stop control CTspidl cannot be permitted in order to avoid a failure to start the engine 12 at the time of restart. For example, when the start using the first starter 16 fails and the start using the second starter 18 also fails, it is conceivable to perform cranking of the engine 12 using the first starter 16. In this case, it is not possible to determine whether the cause of the failure to start using the second starter 18 is due to the state of the low-voltage battery 34, and the start of the engine 12 using the second starter 18 cannot be guaranteed, so the next idling stop control CTspidl cannot be permitted. This leads to a loss of an opportunity for the idling stop control CTspidl. From this perspective, if starting using the first starting device 16 fails and starting using the second starting device 18 also fails, it is useful to crank the engine 12 again using the second starting device 18.

[0051] FIG. 3 is a flowchart illustrating the main control operations of the electronic control device 70, which are for increasing the probability of successful starting of the engine 12. For example, this is executed when there is a request to restart the engine 12 following release of the idling stop control CTspidl.

[0052] In FIG. 3, each step of the flow chart corresponds to a function of the starting control unit 76. In step (hereinafter, step is omitted) S10, it is determined whether or not high-voltage MG starting, which is starting of the engine 12 by the first starting device 16 including the electric motor MG and the high-voltage battery 26, has been successful. If the determination in S10 is negative, in S20, low-voltage starter starting, which is starting of the engine 12 by the second starting device 18 including the starter motor 32 and the low-voltage battery 34, is executed as a backup in case of failure of high-voltage MG starting. Next, in S30, it is determined whether or not low-voltage starter starting has been successful. If the determination in S30 is negative, in S40, restarting by low-voltage starter starting as a backup is executed when low-voltage starter starting fails. Next, in S50, it is determined whether or not low-voltage starter starting has been successful. If the determination in S50 is positive, in S60, it is determined whether or not the starter starting voltage VLst is equal to or higher than a predetermined voltage VLstf. If the determination in S60 is negative, the idling stop prohibition flag is switched on in S70. If the determination in S10 is positive, or if the determination in S60 is positive, or following S70, this routine is ended and the vehicle 10 resumes traveling. If the determination in S50 is negative, this routine is ended and the vehicle 10 stops traveling. At this time, in order to resume the traveling of the vehicle 10, for example, the driver is required to operate the start button 24.

[0053] As described above, according to this embodiment, when starting the engine 12 by cranking the engine 12 using the first starting device 16 fails, if starting by cranking the engine 12 using the second starting device 18 also fails, cranking of the engine 12 is performed again using the second starting device 18, so there is a possibility that starting will be successful by reattempting cranking using the second starting device 18, which may have failed due to a temporary overlap between the operation of the starter motor 32 and the operation of the electric load 22. Thus, when starting the engine 12, the probability of successful starting can be increased.

[0054] Furthermore, according to this embodiment, when starting the engine 12, cranking using the first starting device 16 is performed preferentially over cranking using the second starting device 18, and when starting using the second starting device 18 can be guaranteed, the idling stop control CTspidl is permitted, while when starting using the second starting device 18 cannot be guaranteed, the idling stop control CTspidl is prohibited, thereby avoiding or suppressing failure to start the engine 12 after releasing the idling stop control CTspidl.

[0055] Furthermore, according to this embodiment, if starting of the engine 12 using the second starting device 18 is successful, it is determined whether starting of the engine 12 using the second starting device 18 can be guaranteed based on whether the starter start-up voltage VLst is equal to or higher than a predetermined voltage VLstf. Therefore, the state of the low-voltage battery 34 can be determined by the starter start-up voltage VLst, and prohibition of the idling stop control CTspidl due to the state of the low-voltage battery 34 being uncertain, i.e., loss of opportunity, can be avoided.

[0056] Furthermore, according to this embodiment, when the vehicle 10 is in a predetermined extremely low temperature environment where it is determined that the electric motor MG cannot be properly controlled when starting the engine 12, cranking is performed using the second starting device 18 instead of cranking using the first starting device 16, thereby avoiding or suppressing failure to start the engine 12.

[0057] Furthermore, according to this embodiment, the idling stop control CTspidl includes the normal idling stop control S&S and the idling stop control FIS when the vehicle has not yet started, so that the energy efficiency can be improved.

[0058] Although the embodiment of the present invention has been described in detail above with reference to the drawings, the present invention can be applied to other embodiments.

[0059] For example, in the above embodiment, the flowchart in Fig. 3 is executed when there is a request to restart the engine 12 in response to the release of the idling stop control CTspidl, but this is not limiting. For example, the flowchart in Fig. 3 may be executed when there is an initial request to start the engine 12 in response to, for example, the vehicle power supply being changed from "OFF" to "IG-ON."

[0060] In the above embodiment, the idling stop control CTspidl includes the normal idling stop control S&S and the idling stop control FIS when the vehicle has not yet started, but it is sufficient if the idling stop control CTspidl includes at least one of the normal idling stop control S&S and the idling stop control FIS when the vehicle has not yet started. Even in this case, a certain effect of improving energy efficiency can be obtained.

[0061] In the above-described embodiment, the vehicle 10 may be a series hybrid vehicle or the like, and does not necessarily need to include the automatic transmission 14.

[0062] It should be noted that the above is merely one embodiment, and the present invention can be embodied in various modified and improved forms based on the knowledge of those skilled in the art. [Explanation of symbols]

[0063] 10: Vehicle 12: Engine 16: First starting device 18: Second starting device 22: Electrical load 26: High voltage battery (high voltage power supply) 32: Starter motor 34: Low voltage battery (low voltage power supply) 70: Electronic control device (control device) 76: Start control unit MG: Electric motor

Claims

1. A control device for a vehicle including an engine, a first starting device having an electric motor connected to the engine so as to be capable of transmitting power and a high-voltage power supply device which supplies and receives electric power to the electric motor, and which cranks the engine using the electric motor, a second starting device having a starter motor provided so as to be capable of rotating the engine and a low-voltage power supply device which is provided so as to be chargeable by the high-voltage power supply device and which supplies electric power to the starter motor, and which cranks the engine using the starter motor, and a plurality of types of electric loads which are temporarily operated by electric power supplied from the low-voltage power supply device, A vehicle control device comprising: a start control unit that, when starting the engine, gives priority to cranking using the first starting device over cranking using the second starting device, and if the starting by cranking using the first starting device fails, performs the cranking using the second starting device, and if the starting by cranking using the first starting device fails and the starting by cranking using the second starting device also fails when the starting by cranking using the first starting device fails, performs the cranking using the second starting device again rather than performing the cranking using the first starting device.

2. The cranking using the second starting device serves as a backup function when starting the engine, The vehicle control device according to claim 1, characterized in that the start control unit allows idling stop control to temporarily stop operation of the engine when the start using the second starting device can be guaranteed, and prohibits the idling stop control when the start using the second starting device cannot be guaranteed.

3. 3. The vehicle control device according to claim 2, characterized in that, when the starting using the second starting device is successful, the starting control unit determines whether the starting using the second starting device can be guaranteed based on whether the output voltage of the low-voltage power supply device during the cranking transition using the second starting device is equal to or higher than a predetermined voltage.

4. The vehicle control device according to claim 2 or 3, characterized in that, when the vehicle is in a predetermined extremely low temperature environment at which it is determined that the electric motor cannot be properly controlled when starting the engine, the start control unit performs the cranking using the second starting device instead of the cranking using the first starting device.

5. 4. The vehicle control device according to claim 2 or 3, characterized in that the idling stop control includes at least one of a control for temporarily stopping the operating engine while the vehicle is running or stopped, and a control for causing the engine to wait in a stopped state without starting it when the vehicle has not yet started after being powered on.

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