JP6521301B2 - Vehicle steering system - Google Patents

Description

  The present invention relates to a vehicle steering apparatus used for a vehicle such as a car.

  As a vehicle steering apparatus, a so-called steer-by-wire (SBW: Steer-By-Wire) -type vehicle steering apparatus is known in which a steering member and a steering mechanism are not mechanically connected. For example, Patent Document 1 below discloses a steer-by-wire type vehicle steering apparatus capable of mechanically connecting a steering wheel as a steering member and a steering mechanism via an electromagnetic clutch. In the normal state, the electromagnetic clutch is in the released state, and steering control is performed in the steer-by-wire mode (SBW mode). When steering control is performed in the steer-by-wire mode, if any abnormality occurs, the electromagnetic clutch is engaged and steering control is performed in the power steering (EPS: Electric Power Steering) mode.

JP, 2014-218192, A

  In a steer-by-wire type vehicle steering apparatus capable of mechanically connecting a steering wheel and a steering mechanism via an electromagnetic clutch, generally, when the ignition key is operated to the on position, the electromagnetic clutch It is released and shifts to the SBW mode. However, when the ignition key is operated from the off position to the ACC (accessory) position, the steering wheel lock is released by the steering wheel lock device, but the electromagnetic clutch remains engaged and does not shift to the SBW mode. . When the driver operates the steering wheel when the ignition key is in the ACC position, torque may be applied to the electromagnetic clutch, which may cause the electromagnetic clutch to bite.

  If the electromagnetic clutch is engaged when the ignition key is in the ACC position, then, although the ignition key is operated to the on position and the clutch release command is output, the electromagnetic clutch maintains the engaged state there's a possibility that. When the electromagnetic clutch shifts to the SBW mode with the clutch maintained in the engaged state, a torque unexpected by the driver is generated in the steering wheel, and so-called steering wheel removal may occur.

  An object of the present invention is to provide a steering apparatus for a vehicle in which the clutch is unlikely to be engaged when the ignition key is in the ACC position.

  The invention according to claim 1 comprises a steering member (2) for steering the vehicle, a steering mechanism (4) for steering the steered wheels (3), and locking of the movement of the steering member Lock mechanism (10), a clutch (6) for mechanically connecting or disconnecting the steering member and the steering mechanism, and a reaction force motor (for applying a reaction force to the steering member 14), a steering motor (31) for driving a steering mechanism in a state where the clutch is released, and a steering torque detection means (12) for detecting a steering torque applied to the steering member A steering apparatus (1) for a vehicle including: when the ignition key is in the ACC position, the detected steering torque detected by the steering torque detection means after the lock of the steering member by the lock mechanism is released But Monitoring means (40) for monitoring whether or not a predetermined value has been exceeded, and clutch release command output means (for outputting a clutch release command for releasing the clutch when the detected steering torque has exceeded a predetermined value) 40) and a vehicle steering apparatus. In addition, although the alphanumeric characters in parenthesis represent the corresponding component etc. in the below-mentioned embodiment, of course, the scope of the present invention is not limited to the embodiment. Hereinafter, the same applies in this section.

  In this configuration, when the detected steering torque becomes equal to or greater than a predetermined value when the ignition key is in the ACC position, a clutch release command is output. This makes it possible to release the clutch before a large torque (steering torque) is applied to the clutch in the engaged state. For this reason, when the ignition key is in the ACC position, even if the steering member is operated, the clutch is less likely to bite. As a result, when transitioning to the SBW mode, so-called handle removal is less likely to occur.

  In the invention according to claim 2, after the clutch release command is output by the clutch release command output means, a determination means (40) for determining whether or not the clutch is released, and the clutch by the determination means When it is determined that the steering wheel is released, the operation mode is shifted to a steer-by-steer mode in which steering of the steered wheels is performed in a state where the steering member and the steering mechanism are not mechanically connected, A means for shifting the operation mode to the failsafe mode in which the steered wheels are steered in a state where the steering member and the steering mechanism are mechanically coupled when it is determined that the clutch is not released The vehicle steering apparatus according to claim 1, further comprising:

FIG. 1 is a schematic view showing a schematic configuration of a vehicle steering system according to an embodiment of the present invention. FIG. 2 is a flowchart showing a procedure of processing (processing in an ACC state) executed by the ECU when the ignition key is in the ACC position.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a schematic view showing a schematic configuration of a vehicle steering system according to an embodiment of the present invention.
The vehicle steering system 1 includes a steering wheel 2 as a steering member for steering the vehicle, a steering mechanism 4 for steering the steered wheels 3, and a steering shaft 5 connected to the steering wheel 2. It includes a clutch 6 for mechanically connecting and disconnecting the steering shaft 5 (steering wheel 2) and the steering mechanism 4. In this embodiment, the clutch 6 is an electromagnetic clutch. The clutch 6 operates an input shaft (not shown), an output shaft (not shown), a clutch mechanism (not shown) for transmitting and blocking torque between them, and engagement and release of the clutch mechanism. And an excitation unit (not shown).

The steering shaft 5 is a torsion that connects the first shaft 7 connected to the steering wheel 2, the second shaft 9 integrally connected to the input shaft of the clutch 6, and the first shaft 7 and the second shaft 9. Including bar 8;
In the vicinity of the first shaft 7, a handle lock device 10 for locking the rotation of the steering wheel 2 is provided. The steering wheel lock device 10 includes a lock mechanism (not shown) driven by a motor (not shown) to lock the rotation of the steering wheel 2.

  A steering angle sensor 11 for detecting a steering angle θs which is a rotation angle of the first shaft 7 is disposed around the first shaft 7. In this embodiment, the steering angle sensor 11 detects the amount of rotation (rotation angle) of the first shaft 7 in both forward and reverse directions from the neutral position of the first shaft 7 and rotates from the neutral position to the right. The amount is output as, for example, a positive value, and the amount of rotation from the neutral position to the left is output as, for example, a negative value.

  In addition, a torque sensor 12 is disposed around the steering shaft 5. The torque sensor 12 detects the steering torque T applied to the steering wheel 2 based on the relative rotational displacement of the first shaft 7 and the second shaft 9, that is, the torsion angle of the torsion bar 8. In this embodiment, the steering torque T detected by the torque sensor 12 is detected as a positive torque for steering in the right direction and a negative torque for steering in the left direction. The magnitude of the steering torque is increased as the absolute value is increased.

  A reaction force motor 14 is connected to the second shaft 9 via a reduction gear 13. The reaction force motor 14 is an electric motor for applying a steering reaction force (a torque in the direction opposite to the steering direction) to the steering wheel 2. The reduction gear 13 meshes with the worm shaft (not shown) integrally rotatably coupled to the output shaft of the reaction force motor 14, and is integrally rotatably coupled to the second shaft 9. It comprises a worm gear mechanism including a worm wheel (not shown). The reaction force motor 14 is provided with a rotation angle sensor 15 for detecting the rotation angle of the reaction force motor 14.

  The steering mechanism 4 includes a first pinion shaft 16 integrally connected to an output shaft of the clutch 6, a rack shaft 17 as a steering shaft, and a steering actuator for applying a steering force to the rack shaft 17. And 30. The steered wheels 3 are connected to each end of the rack shaft 17 through tie rods 18 and knuckle arms (not shown). A first pinion 19 is connected to the tip of the first pinion shaft 16. The rack shaft 17 extends linearly along the left-right direction of the vehicle. A first rack 20 that meshes with the first pinion 19 is formed at a first axial end of the rack shaft 17.

  The steering actuator 30 includes a steering motor 31, a reduction gear 32, a second pinion shaft 33, a second pinion 34, and a second rack 35. The second pinion shaft 33 is disposed separately from the steering shaft 5. The reduction gear 32 meshes with the worm shaft (not shown) integrally rotatably coupled to the output shaft of the steering motor 31 and the worm shaft, and is integrally rotatably coupled to the second pinion shaft 33. And a worm gear mechanism (not shown).

  The second pinion 34 is connected to the tip of the second pinion shaft 33. The second rack 35 is provided on the second end side opposite to the first end in the axial direction of the rack shaft 17. The second pinion 34 meshes with the second rack 35. The steering motor 31 is provided with a rotation angle sensor 36 for detecting the rotation angle of the steering motor 31. In the vicinity of the rack shaft 17, a stroke sensor 37 for detecting an amount of movement of the rack shaft 17 in the axial direction is disposed. The steering angle θr of the steered wheels 3 is detected from the axial movement amount of the rack shaft 17 detected by the stroke sensor 37.

  Detection signals of the steering angle sensor 11, the torque sensor 12, the rotation angle sensors 15, 36, the stroke sensor 37, the vehicle speed sensor 38 and the state detection signal of the ignition key are input to an ECU (Electronic Control Unit) 40 . The ECU 40 controls the steering wheel lock device 10, the clutch 6, the reaction force motor 14 and the steering motor 31 based on these input signals. Specifically, the ECU 40 includes drive circuits (not shown) for the steering wheel lock device 10, the clutch 6, the reaction force motor 14 and the steering motor 31, and a microcomputer (not shown) for controlling the drive circuits. And contains.

  The vehicle steering system 1 has a steer-by-wire mode (hereinafter, referred to as "SBW mode"), a failsafe mode, and the like as operation modes. The SBW mode is a mode in which the steered wheels 3 are steered in a state where the steering wheel 2 and the steering mechanism 4 are not mechanically connected (the clutch 6 is released). The fail safe mode is a mode in which the steered wheels 3 are steered in a state in which the steering wheel 2 and the steering mechanism 4 are mechanically coupled (the clutch 6 is engaged), and in the SBW mode This mode is automatically set when an error occurs. In this embodiment, the fail safe mode is a power steering mode (EPS mode) in which a steering assist force corresponding to a steering torque or the like is generated by at least one of the reaction force motor 14 and the steering motor 31. The fail safe mode may be a manual steering mode in which steering is performed only manually.

  In the SBW mode, the ECU 40 generates a reaction force based on, for example, the steering angle θs detected by the steering angle sensor 11, the steering torque T detected by the torque sensor 12, the vehicle speed V detected by the vehicle speed sensor 38, etc. The motor 14 and the steering motor 21 are controlled. Specifically, the ECU 40 calculates a reaction torque target value based on the steering angle θs, the steering torque T and the vehicle speed V, and a motor torque corresponding to the reaction torque target value is generated from the reaction motor 14. , Control the reaction force motor 14. Further, the ECU 40 calculates a turning angle target value based on the steering angle θs, the steering torque T and the vehicle speed V, and the turning angle θr of the turning wheel 3 calculated from the output of the stroke sensor 37 is a turning angle target value The steering motor 31 is controlled to be equal to

In the EPS mode, the ECU 40 calculates a motor current command value corresponding to the assist torque target value based on, for example, the steering angle θs, the steering torque T, and the vehicle speed V, and the steering motor 31 (or reaction force motor 14). The steering motor 31 (or the reaction force motor 14) is controlled so that the motor current of the motor current becomes equal to the motor current command value.
The ECU 40 recognizes the state of the ignition key based on the state detection signal of the ignition key. When the ignition key is not inserted into the key cylinder and when the ignition key is in the off position, the clutch 6 is in the engaged state. When the ignition key is operated to the on position, the ECU 40 shifts the operation mode to the SBW mode after releasing the clutch 6. If some abnormality occurs in the SBW mode, the ECU 40 shifts the operation mode to the failsafe mode (EPS mode in this embodiment) after engaging the clutch 6. When the ignition key is operated from the on position to the off position, the ECU 40 engages the clutch 6.

FIG. 2 is a flowchart showing a procedure of processing (processing in an ACC state) executed by the ECU 40 when the ignition key is in the ACC position.
When the ignition key (IG key) is operated to the ACC (accessory) position (step S1), the ECU 40 unlocks the steering wheel 2 by the steering wheel lock device 10 (step S2). Thereafter, the ECU 40 determines whether the ignition key is still at the ACC position (step S3).

If the ignition key is in the ACC position (step S3: YES), the ECU 40 determines whether the absolute value | T | of the steering torque T detected by the torque sensor 12 is equal to or greater than a predetermined value A (A> 0). It discriminates (step S4). If the absolute value | T | of the steering torque T is less than the predetermined value A (step S4: NO), the ECU 40 returns to step S3.
If it is determined in step S3 that the ignition key is not at the ACC position (step S3: NO), the ECU 40 ends the current process (process in the ACC state).

If it is determined in step S4 that the absolute value | T | of the steering torque T is greater than or equal to the predetermined value A (step S4: YES), the ECU 40 can prevent the clutch 6 from being engaged. Outputs a clutch release command to the drive circuit of the clutch 6 (step S5). As a result, power is supplied to the excitation unit for releasing the clutch 6.
Thereafter, the ECU 40 determines whether the clutch 6 is released (step S6). In other words, the ECU 40 determines whether the clutch 6 is maintained in the engaged state by the engagement despite the output of the clutch release command. In this determination, for example, it is determined whether or not the absolute value | T | of the steering torque T detected by the torque sensor 12 is less than or equal to a predetermined value B (B> 0) while the steering motor 31 is driven. You can do this by When the clutch 6 is released, the motor torque generated by the steering motor 31 is not transmitted to the steering shaft 5, so the absolute value | T | of the steering torque T detected by the torque sensor 12 is a predetermined value B. It becomes below. On the other hand, when the clutch 6 is maintained in the engaged state, the motor torque generated by the steering motor 31 is transmitted to the steering shaft 5 via the steering mechanism 4 and the clutch 6, so detection by the torque sensor 12 The absolute value of the steering torque T that is obtained is larger than the predetermined value B.

  When the steering motor 31 is driven, the angular deviation between the steering shaft 5 connected to the input shaft of the clutch 6 and the first pinion shaft 16 connected to the output shaft of the clutch 6 has a predetermined value C It may be determined whether or not the clutch 6 is released based on whether C> 0 or more. If the angular deviation between the steering shaft 5 and the first pinion shaft 16 is equal to or greater than a predetermined value C, it is determined that the clutch 6 is released.

If it is determined in step S6 that the clutch 6 is released (YES in step S6), the ECU 40 shifts the operation mode to the SBW mode (step S7). Then, the current process (process in the ACC state) is ended.
When it is determined in step S6 that the clutch 6 is not released (step S6: NO), the ECU 40 outputs a clutch engagement command for engaging the clutch 6 to the drive circuit of the clutch 6 (step S8). Thereby, the power supply to the exciting unit for releasing the clutch 6 is stopped. Thereafter, the ECU 40 shifts the operation mode to the failsafe mode (EPS mode) (step S9). Then, the current process (process in the ACC state) is ended.

  In the above embodiment, when the ignition key is operated to the ACC position, the steering wheel lock is released (see steps S1 and S2). Thereafter, when the ignition key is still at the ACC position, it is monitored whether or not the absolute value | T | of the steering torque T detected by the torque sensor 12 has become equal to or greater than the predetermined value A (see steps S3 and S4). . Then, when the absolute value | T | of the steering torque T becomes equal to or greater than the predetermined value A, a clutch release command for releasing the clutch 6 is output (see steps S4 and S5). This makes it possible to release the clutch 6 before a large torque (steering torque) is applied to the clutch 6 in the engaged state. Therefore, when the ignition key is in the ACC position, even if the steering wheel 2 is operated, the clutch 6 is less likely to bite.

Thereafter, it is determined whether or not the clutch 6 is released. If it is determined that the clutch 6 is released, the operation mode shifts to the SBW mode (see steps S6 and S7). This enables steering in the SBW mode. In this case, since the clutch is released, so-called steering wheel removal does not occur.
On the other hand, if it is determined in the clutch release determination that the clutch 6 is engaged, the operation mode shifts to the failsafe mode (EPS mode in this example) after the clutch engagement command is output (steps S6, S8, See S9). This enables steering in the EPS mode.

  As mentioned above, although embodiment of this invention was described, this invention can also be implemented with another form. For example, in the above embodiment, after outputting the clutch release command in step S5 of FIG. 2, the ECU 40 determines whether or not the clutch 6 is released, and the operation mode is SBW mode or failsafe mode according to the determination result. (In this example, it is shifted to the EPS mode) (see steps S5 to S9 in FIG. 2). However, in this way, even after the operation mode shifts to the SBW mode or the EPS mode, when the state where the ignition key is in the ACC position is maintained, the reaction force motor is operated each time the steering wheel 2 is operated. Since both or one of the steering motor 14 and the steering motor 31 are driven, the battery may be lifted. Therefore, the ECU 40 may lock the steering wheel 2 by the steering wheel lock device 10 after outputting the clutch release command in step S5 of FIG. 2 so that the battery does not run out. In this case, in order to enable steering, the driver must operate the ignition key to the off position and then operate the ACC key to release the steering wheel lock.

In the above embodiment, the turning angle θr of the turning wheel 3 is detected from the axial movement amount of the rack shaft 17 detected by the stroke sensor 37. However, the turning angle θr of the turning wheel 3 is the rotation angle sensor 36 It may be detected based on the rotation angle detected by
In addition, various design changes can be made within the scope of matters described in the claims.

  DESCRIPTION OF SYMBOLS 1 ... Steering device for vehicles, 2 ... Steering wheel, 3 ... Steering wheel, 4 ... Steering mechanism, 10 ... Steering wheel lock apparatus, 6 ... Clutch, 12 ... Torque sensor, 14 ... Reaction force motor, 31 ... Steering motor, 40 ... ECU

Claims (2)

A steering member for steering a vehicle, a steering mechanism for steering steered wheels, a lock mechanism for locking the movement of the steering member, the steering member and the steering mechanism are mechanically provided. A clutch for connecting or disconnecting to the motor, a reaction force motor for applying a reaction force to the steering member, and a steering motor for driving the steering mechanism in a state where the clutch is released; And a steering torque detection means for detecting a steering torque applied to the steering member,
When the ignition key is in the ACC position, monitoring is performed to monitor whether or not the detected steering torque detected by the steering torque detection means has become equal to or greater than a predetermined value after releasing the lock of the steering member by the lock mechanism. Means,
And a clutch release instruction output unit configured to output a clutch release instruction for releasing the clutch when the detected steering torque becomes equal to or greater than a predetermined value. Determining means for determining whether or not the clutch is released after the clutch release command is output by the clutch release command output means;
When the determination means determines that the clutch is released, the steering wheel is steered in a steer-by-steer mode in which the steering wheel is steered in a state where the steering member and the steering mechanism are not mechanically connected. When it is determined that the operation mode is shifted and it is determined that the clutch is not released, a failsafe mode is performed in which steering of the steered wheels is performed in a state where the steering member and the steering mechanism are mechanically coupled. The vehicle steering apparatus according to claim 1, further comprising: means for shifting the operation mode.

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