Vehicle control device

Abstract

To provide a vehicle control device that can prevent the stoppage of evacuation traveling by suppressing a drop in the battery voltage of an auxiliary battery.SOLUTION: A vehicle 10 comprises: an engine 12; an electric motor MG that is connected to a power transmission path between the engine 12 and a pair of drive wheels 14 so as to be able to transmit power; a clutch K0 that disconnects and connects the power transmission between the engine 12 and the electric motor MG; a main battery 60 that can exchange electric power with the electric motor MG; an alternator 72 that is rotatively driven by the engine 12; an auxiliary battery 66 that can be charged with the electric power generated by the alternator 72, has a lower voltage than the main battery 60, and supplies electric power to an auxiliary device 74; and a DC / DC converter 68 that is provided between the main battery 60 and the auxiliary battery 66. During evacuation traveling in a BEV traveling mode, if the battery voltage Vbat of the auxiliary battery 66 is less than a judgement voltage value Vbat_jdg, an electronic control unit 90 puts the clutch K0 into an engagement state and the alternator 72 into a power generation state.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a control device for a vehicle equipped with a clutch that disconnects power transmission between an engine and an electric motor, a main battery that can exchange power with the electric motor, and an auxiliary battery that can be charged with power generated by an alternator that is driven by the engine, has a lower voltage than the main battery, and supplies power to auxiliary equipment. [Background technology]

[0002] There are known vehicles in which the engine and motor generator are connected via a clutch, and the alternator can be driven to rotate by the motor generator even when the clutch is disengaged. For example, the vehicle control device described in Patent Document 1 operates the motor generator as an electric motor and puts the alternator into a power generating state when the battery voltage of the auxiliary battery drops while the vehicle is running with the clutch disengaged. This charges the auxiliary battery. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 8-79915 Summary of the Invention [Problem to be solved by the invention]

[0004] In some vehicles, the engine and the electric motor are connected via a clutch, and when the clutch is disengaged, the alternator is driven by the engine. In such vehicles, if an engine failure or gas shortage occurs, the engine is stopped, the clutch is disengaged, and the vehicle enters emergency driving mode using only the electric motor as a power source. During emergency driving, the alternator cannot generate power. Therefore, if the load on the auxiliary battery is heavy, the battery voltage of the auxiliary battery may drop, rendering the auxiliary equipment unusable and disabling the vehicle, which could result in the vehicle being unable to drive, and thus the emergency driving mode being canceled.

[0005] The present invention was made against the background of the above circumstances, and its purpose is to provide a vehicle control device that can prevent the suspension of evacuation driving by suppressing a drop in the battery voltage of the auxiliary battery. [Means for solving the problem]

[0006] The gist of the present invention is a control device for a vehicle comprising an engine, an electric motor connected to a power transmission path between the engine and a pair of drive wheels so as to be able to transmit power, a clutch that disconnects the power transmission between the engine and the electric motor, a main battery that can exchange power with the electric motor, an alternator that is driven and rotated by the engine, an auxiliary battery that can charge the power generated by the alternator, has a lower voltage than the main battery, and supplies power to auxiliary equipment, and a DC / DC converter provided between the main battery and the auxiliary battery, wherein, during evacuation driving that does not use the engine as a power source and uses the electric motor as a power source, when the battery voltage of the auxiliary battery is less than a predetermined judgment voltage value, the clutch is engaged and the alternator is put into a generating state. [Effects of the Invention]

[0007] According to the control device of the present invention, during evacuation running in which the engine is not used as a power source and the electric motor is used as a power source, if the battery voltage of the auxiliary battery is less than a predetermined threshold voltage value, the clutch is engaged and the alternator is put into a generating state. By engaging the clutch, the engine is rotated by the electric motor, and the alternator is accordingly put into a generating state. As a result, the electric power generated by the alternator is charged into the auxiliary battery, thereby suppressing a drop in the battery voltage of the auxiliary battery and suppressing the cancellation of evacuation running. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a schematic configuration diagram of a vehicle equipped with an electronic control device according to an embodiment of the present invention; [Figure 2] 4 is an example of a flowchart illustrating a control operation of an electronic control device. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that in the embodiments, the drawings are appropriately simplified or modified, and the dimensional ratios and shapes of the various parts are not necessarily drawn accurately. [Example]

[0010] FIG. 1 is a schematic diagram of a vehicle 10 equipped with an electronic control device 90 according to an embodiment of the present invention.

[0011] The vehicle 10 includes an engine 12 and an electric motor MG as power sources for traveling, and a power transmission device 16 provided in a power transmission path between the engine 12 and a pair of drive wheels 14. The engine 12 is a well-known internal combustion engine. The electric motor MG has at least an electric motor function, either an electric motor function or a generator function. The electric motor MG is configured, for example, as a motor-generator, and is a three-phase synchronous motor. The power transmission device 16 includes, in order from the engine 12 side, an engine connecting shaft 20, a clutch K0, a rotor shaft 22 non-rotatably connected to the rotor of the electric motor MG, a torque converter 24, an input shaft 26, an automatic transmission 28, and the like, all of which are well-known components, within a case 18 that is a non-rotating member. The power transmission device 16 includes, in order from the automatic transmission 28 side, an output shaft 30, a differential 32, a pair of axles 34, and the like, all of which are well-known components. In this way, the electric motor MG is connected to the power transmission path between the engine 12 and the pair of drive wheels 14 so as to be capable of transmitting power. The clutch K0 is a clutch that connects and disconnects the power transmission between the engine 12 and the electric motor MG, and corresponds to the "clutch" of the present invention.

[0012] The vehicle 10 includes an inverter 52, a hydraulic control circuit 54, an EOP 56 which is an electric oil pump, a main battery 60, a system main relay 62 (hereinafter simply referred to as "relay 62"), an auxiliary battery 66, a DC / DC converter 68, a starter motor 70, and an alternator 72, which are well-known components and are configured as shown in FIG. 1.

[0013] The inverter 52 converts the direct current supplied from the main battery 60 into alternating current and outputs it to the electric motor MG, and also converts the alternating current generated by the electric motor MG into direct current and outputs it to the main battery 60. In this way, the main battery 60 can exchange power with the electric motor MG.

[0014] The alternator 72 is a well-known alternator that is rotationally driven by the engine 12. The electric power generated by the alternator 72 is charged into the auxiliary battery 66.

[0015] The main battery 60 is a high-voltage battery used primarily to supply power to drive the electric motor MG and to charge the electric power generated by the electric motor MG through regeneration. The auxiliary battery 66 is a battery used primarily to supply power to the auxiliary devices 74. The auxiliary devices 74 include accessories such as headlights, power window drive motors, a navigation system, an audio system, and an ETC (electronic toll collection system), all of which are not shown, as well as an electronic control device 90. Due to differences in their uses, the main battery 60 has a higher battery voltage than the auxiliary battery 66. For example, the battery voltage Vbat [V] of the auxiliary battery 66 is 12 [V] when fully charged, whereas the battery voltage of the main battery 60 is higher when fully charged. Thus, the auxiliary battery 66 is a well-known battery that can be charged with electric power generated by the alternator 72, has a lower voltage than the main battery 60, and supplies electric power to the auxiliary devices 74.

[0016] A power line 64 and a relay 62 are provided between the inverter 52 and the main battery 60. A DC / DC converter 68 is provided between the power line 64 and the auxiliary battery 66. The DC / DC converter 68 is a power supply circuit that steps up and down a direct current. For example, the DC / DC converter 68 steps down the voltage supplied from the main battery 60 to the power line 64 to charge the auxiliary battery 66, or steps up the direct current supplied from the auxiliary battery 66 to output it to the power line 64. In this way, the DC / DC converter 68 is provided between the main battery 60 and the auxiliary battery 66.

[0017] The MOP 42 is a well-known mechanical oil pump that is connected to, for example, a pump impeller of the torque converter 24 and driven by at least one of the engine 12 and the electric motor MG. The EOP 56 is a well-known oil pump that can be driven by the rotation of an EOP drive motor 58, independently of the rotation of the engine 12 and the electric motor MG.

[0018] The hydraulic control circuit 54 uses the hydraulic pressure of the hydraulic oil OIL discharged from the MOP 42 and the EOP 56 as the source pressure and supplies the necessary hydraulic oil OIL to each part in the case 18 .

[0019] The vehicle 10 can select one of three driving modes: a BEV driving mode, an engine driving mode, and an HEV driving mode. The BEV driving mode is a driving mode in which the engine 12 is stopped and the electric motor MG is powered, thereby performing BEV (Battery Electric Vehicle) driving using only the electric motor MG as a power source. The engine driving mode is a driving mode in which the clutch K0 is engaged and the engine 12 is used as a power source. In the engine driving mode, the electric motor MG is in a non-driven state, and the rotor shaft 22 of the electric motor MG is rotated by the engine 12. The HEV driving mode is a driving mode in which the clutch K0 is engaged and the HEV (Hybrid Electric Vehicle) driving is performed using both the engine 12 and the electric motor MG as power sources.

[0020] The vehicle 10 is equipped with an electronic control device 90. The electronic control device 90 is configured to include, for example, a so-called microcomputer, and performs various controls of the vehicle 10 by performing signal processing in accordance with pre-stored programs. The electronic control device 90 corresponds to the "control device" in this invention.

[0021] Various signals (e.g., accelerator opening θacc [%], which is the driver's accelerator operation amount indicating the magnitude of the driver's acceleration operation, vehicle speed V [km / h], battery charge / discharge current Ibat [A] and battery voltage Vbat of the auxiliary battery 66, etc.) based on detection values ​​from various sensors (e.g., accelerator opening sensor 80, vehicle speed sensor 82, battery sensor 84, etc.) provided on the vehicle 10 are input to the electronic control device 90. The battery charge / discharge current Ibat is the difference (=Ichg-Idischg) between the charging current Ichg to the auxiliary battery 66 and the discharging current Idischg from the auxiliary battery 66.

[0022] The electronic control device 90 outputs various command signals (e.g., an engine control signal Se for controlling the operation of the engine 12, an electric motor control signal Smg for controlling the operation of the electric motor MG, a shift control signal Sat for controlling the shift of the automatic transmission 28, a K0 control signal Sk0 for controlling the engagement and disengagement of the clutch K0, an LU control signal Slu for controlling the engagement and disengagement of the lock-up clutch LU of the torque converter 24, an EOP control signal Seop for controlling the operation of the EOP drive motor 58, a relay control signal Ssmr for controlling the opening and closing of the relay 62, a converter control signal Scon for controlling the voltage conversion of the DC / DC converter 68, etc.) to each device provided in the vehicle 10 (e.g., the engine 12, the inverter 52, the hydraulic control circuit 54, the EOP drive motor 58, the relay 62, the DC / DC converter 68, etc.).

[0023] The electronic control unit 90 calculates the required drive torque Trdem by applying the actual accelerator opening θacc and vehicle speed V to a map in which the relationship between the accelerator opening θacc, vehicle speed V, and the required drive torque Trdem [N·m] is predetermined and stored, for example, experimentally or by design. The electronic control unit 90 controls the operation of the engine 12 and the electric motor MG so that the drive torque Tr [N·m] transmitted to the pair of drive wheels 14 achieves the required drive torque Trdem, taking into account transmission loss, the gear ratio γat of the automatic transmission 28, the chargeable power Win [W] and dischargeable power Wout [W] of the main battery 60, etc.

[0024] The electronic control unit 90 determines whether to shift the automatic transmission 28 using, for example, a shift map, and executes shift control as necessary. The shift map is a predetermined relationship having shift lines for determining whether to shift the automatic transmission 28 on a two-dimensional coordinate system using, for example, vehicle speed V and required drive torque Trdem as variables. The electronic control unit 90 controls the engagement / disengagement state of the clutch K0, the open / close state of the relay 62, and the operating state (operating state and stopped state) of the DC / DC converter 68 according to the selected driving mode. The electronic control unit 90 also controls the engagement / disengagement state of the lock-up clutch LU of the torque converter 24 according to the vehicle state.

[0025] Next, we will explain the control function of the electronic control device 90 when the electric motor MG is driven and evacuation travel in the BEV travel mode is performed based on the occurrence of a predetermined abnormal state. Evacuation travel in the BEV travel mode corresponds to "evacuation travel using the electric motor as a power source without using the engine as a power source" in this invention.

[0026] The electronic control unit 90 determines whether a predetermined abnormal state has occurred in the vehicle 10. A "predetermined abnormal state" is a predetermined vehicle state in which the operation of the engine 12 must be stopped. For example, the predetermined abnormal state includes an engine failure or running out of gas.

[0027] When the electronic control unit 90 determines that the vehicle 10 is in a predetermined abnormal state, it controls the vehicle 10 to perform evacuation traveling in the BEV traveling mode. Specifically, the relay 62 is controlled to a closed state, the clutch K0 is disengaged, the electric motor MG is controlled to a driving state via the inverter 52, and the engine 12 is controlled to a stopped state. The electric motor torque Tmg [N·m], which is the output torque of the electric motor MG, is controlled to a traveling load torque Tr_ld [N·m] that realizes the required driving torque Trdem. In addition, the electronic control unit 90 controls the shifting of the automatic transmission 28 via the hydraulic control circuit 54 and controls the DC / DC converter 68 to an operating state. During evacuation traveling in the BEV traveling mode, the DC / DC converter 68 is controlled to charge the auxiliary battery 66 using power from the main battery 60 in accordance with the battery voltage Vbat.

[0028] When the electronic control unit 90 performs control to execute evacuation traveling, it determines whether the battery voltage Vbat is less than a threshold voltage value Vbat_jdg and whether the battery charge / discharge current Ibat is a negative value. The threshold voltage value Vbat_jdg is a lower limit voltage value of the battery voltage Vbat that is predetermined experimentally or by design so that the auxiliary equipment 74 operates normally. A negative value of the battery charge / discharge current Ibat means that the discharge current Idischg is greater than the charge current Ichg, and the battery voltage Vbat is decreasing even when charging is performed by the DC / DC converter 68. The condition that the battery voltage Vbat is less than the threshold voltage value Vbat_jdg and the battery charge / discharge current Ibat is a negative value is a "power generation necessary condition" that requires power generation by the alternator 72. The "battery voltage Vbat" and the "determined voltage value Vbat_jdg" correspond to the "battery voltage of the auxiliary equipment battery" and the "predetermined threshold voltage value" in this invention, respectively.

[0029] When the electronic control device 90 determines that the battery voltage Vbat is less than the reference voltage value Vbat_jdg and that the battery charge / discharge current Ibat is negative, it places the alternator 72 in a power generating state. Specifically, the clutch K0 is engaged, and the electric motor torque Tmg is controlled to a predetermined power generating load torque Tpg_ld [N·m]. The predetermined power generating load torque Tpg_ld is the sum (=Tr_ld+Te_ld+Talt_ld) of the traveling load torque Tr_ld, the engine load torque Te_ld [N·m] that rotates the stopped engine 12, and the alternator load torque Talt_ld [N·m] associated with power generation by the alternator 72.

[0030] When the electronic control unit 90 places the alternator 72 in a generating state, it determines whether the vehicle 10 is in a driven state. If the electronic control unit 90 determines that the vehicle 10 is in a driven state (for example, the accelerator opening θacc is zero and the vehicle is decelerating or traveling downhill), it controls, for example, the electric motor torque Tmg to zero. This is done to prioritize the use of the driving force transmitted from the pair of drive wheels 14 over power generation by the alternator 72 in order to reduce power consumption of the main battery 60 and prevent a decrease in the distance that can be traveled during evacuation travel. The electronic control unit 90 continues this generating state of the alternator 72 with the clutch K0 engaged for a predetermined period T [s]. After the predetermined period T has elapsed, the electronic control unit 90 places the alternator 72 in a non-generating state and returns to evacuation travel in BEV travel mode. Specifically, the clutch K0 is controlled to a disengaged state, the alternator 72 is controlled to a non-power-generating state, and the electric motor torque Tmg is controlled to be equal to the driving load torque Tr_ld. When the alternator 72 is in a power-generating state, it is not possible to determine whether the power-generation necessary condition has been satisfied. Therefore, the predetermined period T is a period that is determined in advance experimentally or by design in order to determine whether the power-generation necessary condition has been satisfied. When the electronic control device 90 returns to executing evacuation traveling in the BEV traveling mode, it again determines whether the power-generation necessary condition is satisfied and controls the alternator 72 to be in a power-generating state as necessary.

[0031] 2 is an example of a flowchart illustrating the control operation of the electronic control unit 90. This flowchart is repeatedly executed when a predetermined abnormal state occurs in the vehicle 10.

[0032] First, in step (hereinafter, step will be omitted) S10, evacuation traveling is performed in the BEV traveling mode, and in S20, it is determined whether or not the battery voltage Vbat is less than the determination voltage value Vbat_jdg and the battery charge / discharge current Ibat is a negative value. If the determination in S20 is YES, in S30, the clutch K0 is engaged, the alternator 72 is brought into a power generating state, and the electric motor torque Tmg is controlled to a predetermined power generating load torque Tpg_ld (=Tr_ld+Te_ld+Talt_ld). After S30 is executed, in S40, it is determined whether or not the vehicle 10 is in a driven state. If the determination in S40 is YES, the electric motor torque Tmg is controlled to zero. If the determination in S40 is NO or after S50 is executed, in S60, it is determined whether or not a predetermined period T has elapsed. If the determination in S60 is NO, S60 is executed again. If the determination in S60 is YES, in S70, the clutch K0 is controlled to be in a released state, the alternator 72 is controlled to be in a non-power generating state, and the electric motor torque Tmg is controlled to be equal to the running load torque Tr_ld. If the determination in S20 is NO or after S70 is executed, the process returns.

[0033] According to this embodiment, during evacuation traveling when the engine 12 is not used as a power source and the electric motor MG is used as a power source, if the battery voltage Vbat is less than the determination voltage value Vbat_jdg, the clutch K0 is engaged and the alternator 72 is brought into a power generating state. By bringing the clutch K0 into a engaged state, the engine 12 is rotated by the electric motor MG, and accordingly the alternator 72 is brought into a power generating state. As a result, the electric power generated by the alternator 72 is charged into the auxiliary battery 66, thereby suppressing a decrease in the battery voltage Vbat of the auxiliary battery 66 and suppressing the suspension of evacuation traveling.

[0034] The above-described embodiments of the present invention are merely illustrative, and the present invention can be embodied in various forms with various modifications and improvements based on the knowledge of those skilled in the art without departing from the spirit of the present invention. [Explanation of symbols]

[0035] 10: vehicle, 12: engine, 14: pair of drive wheels, 60: main battery, 66: auxiliary battery, 68: DC / DC converter, 72: alternator, 74: auxiliary equipment, 90: electronic control device (control device), K0: clutch (clutch), MG: electric motor, Vbat: battery voltage (battery voltage of auxiliary battery), Vbat_jdg: judgment voltage value (predetermined judgment voltage value)

Claims

[Claim 1] A control device for a vehicle including an engine, an electric motor connected to a power transmission path between the engine and a pair of drive wheels so as to be able to transmit power, a clutch that connects and disconnects power transmission between the engine and the electric motor, a main battery that can exchange electric power with the electric motor, an alternator that is rotationally driven by the engine, an auxiliary battery that can be charged with power generated by the alternator, has a lower voltage than the main battery, and supplies electric power to auxiliary equipment, and a DC / DC converter provided between the main battery and the auxiliary battery, During evacuation running without using the engine as a power source and using the electric motor as a power source, if the battery voltage of the auxiliary battery is less than a predetermined determination voltage value, the clutch is engaged and the alternator is put into a power generating state. A vehicle control device characterized by:

Images