Vehicular steering control device

Abstract

To provide a vehicular steering control device which can sufficiently store charging residual quantity to activate a steer-by-wire system at the time of travel start point of a vehicle even when abnormality occurs in a main electric power source.SOLUTION: A vehicular steering control device is given in which a vehicle 10 is fixed by a vehicle fixing control part 46 while charging a backup power source 34; a vehicle fixing by a vehicle fixing device 38 is not released when a vehicle fixing release request is executed by operation of a vehicle fixing device operation switch 48 until charging residual quantity SOC of the backup power source 34 reaches a charging residual quantity determination value SOC1 to be capable of performing fail-safe set in advance. Thereby, when the vehicle travels after the vehicle fixing is released, the charging residual quantity SOC is at least the charging residual quantity determination value SOC1 to be capable of performing fail-safe or more sufficient to activate a steer-by-wire system at the time of travel start point of the vehicle so that the vehicle steering control device 22 can sufficiently work in a time of emergency.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a vehicle steering control device including a main power source and a backup power source used when the main power source fails.

Background Art

[0002] A vehicle steering control device (steer-by-wire system) is known that mechanically disconnects a steering wheel from steered wheels and controls a steering angle motor that changes the steering angle of the steered wheels according to a steering operation of the steering wheel. For example, the steering control device described in Patent Document 1 is such a device.

[0003] And such a vehicle steering control device may be provided with a main power source and a backup power source used when the main power source fails. Regarding the control between this main power source and the backup power source, although it is for a shift-by-wire system or a brake system, it is described in Patent Document 2. In this case, the backup power source is charged when the vehicle system is started, and when the main power source fails, the backup power source is controlled to backup.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] By the way, in order to make the steer-by-wire system function in an emergency, at least at the start of driving, the backup power source needs to store a sufficient remaining charge (stored power) to operate the steer-by-wire system.

[0006] However, from the perspective that there is sufficient remaining charge stored in the backup power supply at the start of vehicle travel, there is no description in the above prior art, and there is a possibility that the function of the vehicle steering control device cannot be sufficiently obtained.

[0007] The present invention has been made against the background of the above circumstances, and its object is to provide a vehicle steering control device in which, even when the main power supply is abnormal, a sufficient remaining charge (stored power) for operating the steer-by-wire system is stored at the start of vehicle travel.

Means for Solving the Problems

[0008] The gist of the present invention is that (a) the steering wheel and the steered wheels are mechanically separated, and a steering angle motor that changes the steering angle of the steered wheels in response to a steering operation of the steering wheel is controlled using the power of the main power supply, and the backup power supply that backs up the main power supply is a vehicle steering control device in which charging is started when the vehicle is started, and (b) the vehicle is fixed during charging of the backup power supply, and a vehicle fixing control unit that does not release the fixing of the vehicle regardless of a vehicle fixing release request until the remaining charge of the backup power supply reaches a fail-safe implementable charge determination value set in advance is provided.

Effects of the Invention

[0009] According to the vehicle steering control device of the present invention, the vehicle is fixed by the vehicle fixing control unit during charging of the backup power supply, and the fixing of the vehicle is not released regardless of a vehicle fixing release request until the remaining charge of the backup power supply reaches a fail-safe implementable charge determination value set in advance. As a result, when the vehicle is traveling with the fixing released, the remaining charge (stored power) is stored up to the fail-safe implementable charge determination value sufficient to operate the steer-by-wire system at the start of vehicle travel, so that the steer-by-wire system can be made to function in an emergency.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Embodiments for Carrying Out the Invention

[0011] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

Embodiment

[0012] In FIG. 1, the vehicle 10 is provided with a steering wheel (operation wheel) 12 and a pair of steered wheels 14 (for example, front wheels) in a mechanically disconnected state, and the steering angle θw of the steered wheels 14 follows the target steering angle θt determined according to the steering angle θs by the steering operation of the steering wheel 12. A vehicle steering control device (steer-by-wire system) 22 that controls the steering angle θw of the steered wheels 14 is provided, and is controlled by the operation wheel ECU 18 and the steered wheel ECU 20.

[0013] The steering wheel 12 is provided with a reaction force motor 24 that generates a steering reaction force on the steering wheel 12 and an operation angle sensor 26 that detects the steering angle θs of the steering wheel 12. The steered wheels 14 are provided with a steering angle motor 16 that changes the steering angle θw of the steered wheels 14 and a steering angle sensor 28 that detects the steering angle θw of the steered wheels 14. The operation wheel ECU 18 and the steered wheel ECU 20 are connected to be able to communicate signals with each other via a communication line 30.

[0014] The operation wheel ECU 18 and the steering wheel ECU 20 determine a target steering angle θt based on the steering angle θs of the steering wheel 12 according to a relationship preset by a rotation ratio when the steering wheel 12 and the steered wheels 14 are mechanically connected, and drive the steering angle motor 16 so that the steering angle θw of the steered wheels 14 follows the target steering angle θt to control the steering angle θw of the steered wheels 14. On the other hand, the reaction force motor 24 is controlled so as to apply a reaction force corresponding to the road surface condition, the vehicle speed, and the steering angle θw (the caster angle) of the steered wheels 14 to the steering wheel 12. The operation wheel ECU 18 and the steering wheel ECU 20 do not necessarily have to be configured separately, and may be configured from one computer.

[0015] The vehicle 10 is provided with at least a main power supply 32 that supplies power to the vehicle steering control device 22, a backup power supply (battery) 34 that is used in place of the main power supply 32 in the event of a failure of the main power supply 32, and a charge and discharge unit 36 that controls the charging and discharging of the backup power supply 34. The main power supply 32 is composed of a secondary battery that functions as the power supply for the vehicle steering control device (steer-by-wire system) 22. For example, when the vehicle 10 is an HEV vehicle, a BEV vehicle, a PHEV vehicle, an FCEV vehicle, etc., it is a low-voltage (12V) auxiliary battery that is charged from the drive high-voltage battery via a DcDC converter. The failure of the main power supply 32 in this case refers to the failure of the DcDC converter and the output reduction of the auxiliary battery. The backup power supply 34 may be a secondary battery, but is preferably composed of an electric double layer capacitor.

[0016] The charge and discharge unit 36 includes a DCDC converter or the like, and charges the backup power supply 34 using the power supplied from the main power supply 32 according to a command from the electronic control device 40. Further, the charge and discharge unit 36 discharges from the backup power supply 34 according to a command from the electronic control device 40 to supply power to the vehicle steering control device (steer-by-wire system) 22.

[0017] The vehicle 10 is also provided with a vehicle fixing device 38 that blocks the rotation of a pair of steered wheels 14 and a pair of rear wheels (not shown) according to a command from the electronic control unit 40 to fix the vehicle 10. The vehicle fixing device 38 is constituted by, for example, any one of a parking lock mechanism, a parking brake, an electric brake, a hydraulic brake, shift system control, etc.

[0018] The electronic control unit 40 includes, for example, a microcomputer, performs arithmetic processing of input signals according to a program stored in advance, and controls the charge and discharge unit 36 and the vehicle fixing device 38. The electronic control unit 40 functionally includes a main power supply failure determination unit 42, a backup power supply charge and discharge control unit 44, a vehicle fixing control unit 46, etc.

[0019] The main power supply failure determination unit 42 determines a failure of the main power supply 32, such as an output abnormality of the main power supply 32, based on, for example, the output voltage of the main power supply 32.

[0020] When the vehicle power is turned on by a power-on operation of a power switch or an ignition switch or the like (at the time point t1 indicating the start in FIG. 2) in a state where the vehicle 10 is fixed (stopped) by the vehicle fixing device 38, the backup power supply charge and discharge control unit 44 starts charging the backup power supply 34, and when the remaining charge amount SOC of the backup power supply 34 reaches a preset backup possible remaining charge amount determination value SOC1 and the charging is completed, the charging is terminated (at the time point t2 in FIG. 2). Further, during the charging of the backup power supply 34, the backup power supply charge and discharge control unit 44 determines whether or not the remaining charge amount SOC of the backup power supply 34 has reached a preset fail-safe implementable remaining charge amount determination value SOC1.

[0021] The vehicle fixing control unit 46 normally performs vehicle fixing by the vehicle fixing device 38 and release from vehicle fixing in response to the release operation of the vehicle fixing device release operation switch 48. However, when the backup power supply 34 is being charged, until it is determined by the backup power supply charge / discharge control unit 44 that the remaining charge SOC of the backup power supply 34 has reached a preset fail-safe implementable remaining charge determination value SOC1 sufficient to operate the steer-by-wire system for a predetermined time or distance, even if there is a release operation to release the vehicle 10 from the fixed state by operating the vehicle fixing device release operation switch 48, the fixing of the vehicle 10 is continued. The fail-safe implementable remaining charge determination value SOC1 is the remaining charge SOC of the backup power supply 34 sufficient to fully implement the fail-safe in the event of a vehicle power failure, and is determined based on the terminal voltage of the backup power supply 34. When it is determined by the backup power supply charge / discharge control unit 44 that the remaining charge SOC of the backup power supply 34 has reached the preset fail-safe implementable remaining charge determination value SOC1 and the charging is completed, the vehicle fixing control unit 46 performs release of the vehicle fixing by the vehicle fixing device 38 in response to the operation to release the fixing of the vehicle 10.

[0022] In the vehicle 10 equipped with a momentary shifter having an automatic return type shift lever that automatically returns from the D position, R position, and N position to the H position (home position) and a P push switch corresponding to the vehicle fixing device release operation switch 48, when the backup power supply 34 is being charged in the parking lock state, the vehicle fixing control unit 46 does not accept a parking lock release operation by the P push switch or an operation to a traveling position (D position or R position where driving force is output) by the automatic return type shift lever corresponding to the vehicle fixing device release operation switch 48 when the power is turned on (started) in the N position.

[0023] Also, in a vehicle 10 equipped with a mechanical lever shifter having a shift lever that is sequentially operated to the P position, R position, N position, and D position, when the backup power supply 34 is being charged in the parking lock state, the vehicle immobilization control unit 46 locks the shift lever with an electric lock pin so that the shift lever corresponding to the vehicle immobilization device release operation switch 48 does not move from the P position or the N position. Also, while the backup power supply 34 is being charged, the shift lever itself is operable, but the vehicle immobilization control unit 46 invalidates an operation to a traveling position (D position or R position where driving force is output) by the shift lever.

[0024] Also, in a vehicle 10 equipped with an electric parking brake, when the backup power supply 34 is being charged in the operating state of the electric parking brake, the vehicle immobilization control unit 46 does not accept an operation to release the electric parking brake by the vehicle immobilization device release operation switch 48.

[0025] Also, in a vehicle 10 equipped with a manual parking brake, when the backup power supply 34 is being charged in the operating state of the manual parking brake, the vehicle immobilization control unit 46 locks it with an electric lock pin so that the manual parking brake cannot be moved to the unlock side, and invalidates an operation to release the manual parking brake.

[0026] Also, in a vehicle 10 equipped with a hydraulic brake that brakes the rotation of wheels using brake hydraulic pressure generated by operating a brake pedal, when the backup power supply 34 is being charged in the operating state of the hydraulic brake, the vehicle immobilization control unit 46 executes control to maintain the brake hydraulic pressure so that the hydraulic brake is not released even if the brake pedal corresponding to the vehicle immobilization device release operation switch 48 is released.

[0027] FIG. 3 is a flowchart for explaining the main part of the control operation of the electronic control device 40. In step S1 (hereinafter, steps are omitted) in FIG. 3, it is determined whether a power-on (power ON) operation is performed when the system is started during the fixing (stopping) of the vehicle 10 by the vehicle fixing device 38. If the determination in S1 is negative, the operations below S1 are repeated. If the determination is positive, in S2, charging of the backup power supply 34 is started. In S3, even if there is a release operation to release the vehicle 10 from the fixed state by operating the vehicle fixing device release operation switch 48, release of the vehicle fixing device 38 is prohibited and the fixing of the vehicle 10 is continued.

[0028] In S4, it is determined whether the remaining charge amount SOC of the backup power supply 34 has reached a fail-safe executable remaining charge determination value SOC1 set in advance. If the determination in S4 is negative, the execution of operations below S3 is repeated. If the determination in S4 is positive, in S5, release of the vehicle fixing by the vehicle fixing device 38 is permitted. If there is a release operation of the vehicle fixing device release operation switch 48, the vehicle fixing by the vehicle fixing device 38 is released.

[0029] Next, in S6, it is determined whether the main power supply 32 is abnormal. If the determination in S6 is negative, this routine is terminated. If the determination in S6 is positive, in S7, the function of the vehicle steering control device (steer-by-wire system) 22 is maintained by switching from the main power supply 32 to the backup power supply 34, and a notification output indicating the abnormality of the main power supply 32 is performed.

[0030] As described above, according to the vehicle steering control device 22 of the present embodiment, the vehicle 10 is fixed by the vehicle fixing control unit 46 during the charging of the backup power source 34, and until the remaining charge amount SOC of the backup power source 34 reaches the fail-safe executable remaining charge amount determination value SOC1 set in advance, the vehicle fixing by the vehicle fixing device 38 is not released regardless of the vehicle fixing release request by the operation of the vehicle fixing device release operation switch 48. Thereby, when the vehicle is running with the vehicle fixing released, at least the remaining charge amount (stored power) SOC is stored up to the fail-safe executable remaining charge amount determination value SOC1 sufficient to operate the steer-by-wire system at the start point of the vehicle running. Therefore, the vehicle steering control device (steer-by-wire system) 22 can function sufficiently even in an emergency.

[0031] As described above, the embodiments of the present invention have been described in detail with reference to the drawings. However, the present invention can also be applied in other aspects.

[0032] For example, the vehicle 10 in the above-described embodiment may be any of a vehicle equipped with an engine as a power source, a BEV vehicle equipped with an electric motor as a power source, a HEV vehicle equipped with an engine and an electric motor as power sources, a PHEV vehicle, an FCEV vehicle, and the like.

[0033] Note that the above is merely one embodiment, and the present invention can be implemented in various modified and improved forms based on the knowledge of those skilled in the art.

Explanation of Reference Numerals

[0034] 10: Vehicle, 12: Steering wheel, 14: Steered wheels, 16: Steering angle motor, 18: Operation wheel ECU, 20: Steered wheel ECU, 22: Vehicle steering control device (steer-by-wire system), 24 Reaction force motor:, 26: Operation angle sensor, 28: Steering angle sensor, 30: Communication line, 32: Main power source, 34: Backup power source, 36: Charge and discharge unit, 40: Electronic control device, 42: Main power source failure determination unit, 44: Backup power source charge and discharge control unit, 46: Vehicle fixing control unit, 48: Vehicle fixing device release operation switch

Claims

[Claim 1] A steering control device for a vehicle, in which a steering wheel and steered wheels are mechanically separated, a steering motor that changes a steering angle of the steered wheels in response to a steering operation of the steering wheel is controlled using power from a main power source, and a backup power source that backs up the main power source begins to be charged when a power source of the vehicle is turned on, a vehicle fixation control unit that fixes the vehicle while the backup power source is being charged and does not release the fixation of the vehicle regardless of a vehicle fixation release request until the remaining charge of the backup power source reaches a preset remaining charge determination value for enabling a fail-safe operation. A vehicle steering control device comprising:

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