JP2010214978A - Steer-by-wire steering device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a steer-by-wire steering device provided with a fail safe function capable of executing turning even when failure occurs in a turning motor, and adjusting a toe angle. <P>SOLUTION: The steer-by-wire steering device includes a steering wheel 1 not mechanically connected to a steering shaft 10, a steering angle sensor 2 detecting the steering angle, a steering reaction force motor 4 applying reaction torque to the steering wheel 1, and a steering control part 5a controlling two turning motors 6A, 6B and the steering reaction force motor 4. An output transmission mechanism 15 transmitting output of the turning motor 6A to the steering shaft 10 and an output transmission mechanism 16 transmitting output of the turning motor 6B to the steering shaft 10 are provided for executing turning. The output shafts of both the turning motors 6A, 6B are jointed through a sliding screw mechanism 24. When failure occurs in either of both the turning motors, output of the other motor is transmitted to the output transmission mechanism 15 (16) corresponding to the failed turning motor through the sliding screw mechanism 24. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a steer-by-wire steering apparatus in which steering is performed with a steering wheel that is not mechanically connected to a steering shaft for turning.

In this type of steer-by-wire type steering device, there has been proposed a configuration in which a steered wheel is steered by an auxiliary motor even if a steered motor that steers steered wheels fails (Patent Document 1). .
In addition, in a steer-by-wire type steering device in which the left and right wheels in the front wheel system or the rear wheel system are independently steered, a method of obtaining braking force by controlling each of the left and right wheels in a toe-in or toe-out state when an abnormality occurs (Patent Document 2).

JP-A-2005-349845 JP 2005-263182 A

The technology disclosed in Patent Document 1 has a fail-safe function for operating the auxiliary motor when the steering motor fails. However, when the steering motor is normal, the auxiliary motor does not function at all. It is uneconomical.
In addition, the technique disclosed in Patent Document 2 is a method of independently turning each wheel, but because an abnormal wheel becomes uncontrollable, it cannot be normally steered to take an action to avoid danger. There's a problem.

  An object of the present invention is to provide a steer-by-wire type steering apparatus capable of adjusting a toe angle and having a fail-safe function that can be steered even when a steering motor fails.

The steer-by-wire steering device of the present invention includes a steering wheel that is not mechanically connected to a steering shaft for steering, a steering angle sensor that detects a steering angle of the steering wheel, and a reaction force torque applied to the steering wheel. A steering angle signal detected by the steering angle sensor, comprising: a steering reaction force motor to be applied; a steering motor that drives the steering shaft; and a steering control unit that controls the steering reaction force motor and the steering motor. In the steer-by-wire type steering apparatus in which the steering motor is controlled by the steering control unit on the basis of a driving state detection signal including:
That is, the steering shaft is divided into two divided steering shafts for steering the left and right wheels, and two steering motors that independently drive these two divided steering shafts via the left and right output transmission mechanisms, respectively. When the output shafts of both steered motors consist of a pair of screw shafts and sliding screw nuts and each screw shaft is allowed to rotate independently, only one of the screw shafts is rotated. The rotation is coupled by a sliding screw mechanism having a function of transmitting the rotation to the other screw shaft.
This sliding screw mechanism outputs the output of the turning motor on the rotational drive side by rotating the other turning motor in a state where one of the turning motors has failed. The rotation of the shaft can be transmitted to the output shaft of the failed steering motor.

  According to this configuration, since the two steering motors for independently driving the two divided steering shafts for the left and right wheels via the left and right output transmission mechanisms are provided, the steering angle can be controlled independently on the left and right. The toe angle can be adjusted. In addition, the output shaft of both steered motors, the output shaft of both steered motors is made up of screw shafts and sliding screw nuts, allowing independent rotation of each screw shaft and only one of the screw shafts Are coupled by a sliding screw mechanism having a function of transmitting the rotation to the other screw shaft portion, and one of the two turning motors has failed, and the other By rotating the steering motor, the rotation of the output shaft of the steering motor on the rotational drive side can be transmitted to the output shaft of the failed steering motor, so one of the steering motors has failed. In this case, a fail-safe function can be obtained that can be steered only by the other steering motor. Since the sliding screw mechanism has a function of allowing independent rotation of each screw shaft portion, it does not hinder the operation of adjusting the toe angle by controlling the turning angle independently on the left and right.

The sliding screw mechanism having the above function can be realized by, for example, a sliding screw mechanism having the following reverse screw. Specifically, the sliding screw mechanism has a pair of screw shaft portions of mutually opposite screws provided on both output shafts, and a pair of screw grooves of a mutually opposite screw threadedly engaged with both screw shaft portions, respectively. It should be made of nuts. Each of the screw shaft portions may be provided as a part of the output shaft, or may be a shaft coupled to the output shaft.
By providing such a sliding screw nut having screw grooves that are reverse threads, the axial movement of the sliding screw nut with respect to the screw shaft portion is allowed, so that both screw shaft portions can be independently rotated. In addition, due to the low reverse transmission efficiency of the slide screw nut, that is, the low efficiency of converting the axial movement of the slide screw nut into the rotation of the screw shaft, only one screw shaft is rotated. In some cases, the sliding screw nut does not move and transmits rotation to the other screw shaft. For this reason, the rotation of the output shaft of the turning motor on the rotational drive side is lost by rotating the other turning motor in a state where one of the turning motors is lost. It can be transmitted to the output shaft of the falling-side steering motor.

  In the present invention, each of the divided steering shafts has a ball screw shaft part in part, and both the output transmission mechanisms each have a ball nut screwed to the ball screw shaft part of each of the divided steering shafts. The ball nut is rotated by rotation of the steering motor to advance and retract the divided steering shaft in the axial direction, and both split steering shafts are moved in the axial direction by rotation of the both steering motors. Turning and toe angle adjustment may be possible.

  In the present invention, the left and right output transmission mechanisms may be configured to move the split steering shafts in the same direction by rotating the steered motors in the same direction. Further, the both steering motors may be rotated in the same direction by the same rotation angle to move the both divided steering shafts in the same direction by the same amount. Thereby, it becomes possible to steer while maintaining the toe angle.

  In the present invention, the left and right output transmission mechanisms may be configured to move the split steering shafts in opposite directions by rotating the steering motors in opposite directions. Further, the both steering motors may be rotated in the opposite directions by the same rotation angle, thereby moving the both divided steering shafts in the opposite directions by the same amount. Thereby, the toe angle can be adjusted.

  In this invention, the sliding screw mechanism is configured such that when the two turning motors are rotated in the same direction at the same angular velocity, the sliding screw nut is integrally rotated with the output shaft of the turning motor at the same angular velocity. Also good. Thereby, it is possible to steer while maintaining the toe angle. When the sliding screw mechanism is configured to have the pair of reverse screws, when the both turning motors are rotated in the same direction at the same angular velocity, the sliding screw nut is attached to the turning motor. An effect of rotating at the same angular velocity as the output shaft is produced.

  In the present invention, the sliding screw mechanism may be configured such that the sliding screw nut moves to the left and right when the turning motors are rotated in the opposite directions at the same angular velocity. Thereby, the toe angle can be adjusted. When the sliding screw mechanism has the pair of reverse screws, the sliding screw nut moves to the left and right when both the turning motors are rotated in the opposite directions at the same angular velocity. Occurs.

  In this invention, when only one of the two turning motors is rotated, the sliding screw mechanism has a low reverse transmission efficiency of the sliding screw nut, so that the rotation of one of the two turning motors is output from the other turning motor. It may be transmitted to the shaft. The reverse transmission efficiency refers to the efficiency in which the axial movement of the sliding screw nut is converted into the rotation of the screw shaft and transmitted.

  In the present invention, the both steered motors may include a reverse input blocking clutch mechanism that blocks rotation transmission from the output shaft to the motor rotor between the motor rotor and the output shaft. When the reverse input shut-off clutch mechanism is provided, even when a failure occurs in which the rotor of the failed steering motor is stuck, the output by the rotation transmitted from the other steering motor by the sliding screw mechanism The shaft can be rotated.

  The steer-by-wire steering device of the present invention includes a steering wheel that is not mechanically connected to a steering shaft for steering, a steering angle sensor that detects a steering angle of the steering wheel, and a reaction force torque applied to the steering wheel. A steering angle signal detected by the steering angle sensor, comprising: a steering reaction force motor to be applied; a steering motor that drives the steering shaft; and a steering control unit that controls the steering reaction force motor and the steering motor. In the steer-by-wire type steering apparatus in which the steering motor is controlled by the steering control unit based on a driving state detection signal including the steering shaft, the steering shaft is divided into two divided steering shafts for steering the left and right wheels Two steering motors for independently driving these two divided steering shafts via left and right output transmission mechanisms are provided, and both steering motors are provided. The output shaft is composed of a screw shaft and a sliding screw nut, allowing independent rotation of each screw shaft, and when only one of the screw shafts is rotated, the rotation is transmitted to the other screw shaft. It is coupled by a sliding screw mechanism having a function, and this sliding screw mechanism rotates the other steered motor in a state where any one of the steered motors has failed, Since the rotation of the output shaft of the turning motor on the rotational drive side can be transmitted to the output shaft of the failed turning motor, the toe angle can be adjusted and the other turning wheel can be adjusted even when the turning motor fails. It has a fail-safe function that can be steered only by the rudder motor.

1 is a block diagram showing a schematic configuration of a steer-by-wire steering device according to an embodiment of the present invention. It is sectional drawing of the steering shaft drive part in the steer-by-wire type steering apparatus.

  An embodiment of the present invention will be described with reference to the drawings. As shown schematically in FIG. 1, the steer-by-wire steering apparatus includes a steering wheel 1, a steering angle sensor 2, a steering torque sensor 3, a steering reaction force motor 4, and left and right wheels that are steered by a driver. 13 is a steerable axially steerable steering shaft 10 connected via a knuckle arm 12 and a tie rod 11, a steering shaft drive unit 14 for driving the steering shaft 10, a steered angle sensor 8, and a steering. And an ECU (electric control unit) 5 including a controller 5a. The ECU 5 and the steering control unit 5a are configured by a microcomputer and an electronic circuit including a control program thereof.

  The steering wheel 1 is not mechanically connected to a steering shaft 10 for turning. A steering angle sensor 2 and a steering torque sensor 3 are provided for the steering wheel 1 and a steering reaction force motor 4 is connected thereto. The steering angle sensor 2 is a sensor that detects the steering angle of the steering wheel 1. The steering torque sensor 3 is a sensor that detects a steering torque that acts on the steering wheel 1. The steering reaction force motor 4 is a motor that applies reaction force torque to the steering wheel 1.

  The steering control unit 5a of the ECU 5 controls the steering reaction force motor 4 and the turning motors 6A and 6B. In other words, the steering control unit 5a performs a target steering reaction force based on a steering angle signal detected by the steering angle sensor 2, a wheel rotational speed signal detected by a vehicle speed sensor (not shown), and signals of various sensors that detect driving conditions. The steering reaction force motor 4 is controlled by feeding back a steering torque signal detected by the steering torque sensor 3 so that the actual steering reaction force torque matches the target steering reaction force. Further, as described above, the steering control unit 5a selectively sets the rotation direction of both the steering motors 6A and 6B to selectively perform the steering of the wheels 13 and the toe angle adjustment.

  FIG. 2 is a sectional view showing details of the steering shaft driving unit 14 that drives the steering shaft 10. The steering shaft drive unit 14 includes two left and right steering motors 6A and 6B, two left and right output transmission mechanisms 15 and 16, and one sliding screw mechanism 24. The output transmission mechanisms 15 and 16 constitute a reduction gear. The steering shaft 10 is divided into two divided steering shafts 10A and 10B. Ball screw shaft portions 10Aa and 10Ba of the ball screws 25A and 25B are formed on a part of each of the divided steering shafts 10A and 10B, respectively. The two steered motors 6A, 6B are installed in the housing 30 of the steering shaft drive unit 14 with their output shafts 6Aa, 6Ba parallel to the steering shaft 10 and facing each other on the same axis.

  Of the two output transmission mechanisms 15 and 16, the first output transmission mechanism 15 outputs the output of one of the two steering motors 6A and 6B to one of the two divided steering shafts 10A and 10B. This is a mechanism for transmitting to the divided steering shaft 10A. The second output transmission mechanism 16 of the two output transmission mechanisms 15 and 16 outputs the output of the other steering motor 6B of the both steering motors 6A and 6B to the other of the split steering shafts 10A and 10B. This is a mechanism for transmitting to the divided steering shaft 10B.

  The first output transmission mechanism 15 includes a ball screw shaft portion 10Aa of one divided steering shaft 10A, a ball nut 18A screwed to the ball screw shaft portion 10Aa via a ball (not shown), and one rolling shaft. An output gear 19A provided on the output shaft 6Aa of the rudder motor 6A and an input gear 20A fixed to the outer diameter surface of the ball nut 18A and meshing with the output gear 19A. The second output transmission mechanism 16 includes a ball screw shaft portion 10Ba of the other divided steering shaft 10B, a ball nut 18B screwed to the ball screw shaft portion 10Ba via a ball (not shown), and the other rolling shaft. An output gear 19B provided on the output shaft 6Ba of the rudder motor 6B and an input gear 20B fixed to the outer diameter surface of the ball nut 18B and meshing with the output gear 19B. The ball nuts 18A and 18B are supported by the housing 30 via bearings 21A and 21B, respectively.

  The rotation of the output shaft 6Aa of one steered motor 6A is transmitted to the ball nut 18A through the output gear 19A and the input gear 20A of the first output transmission mechanism 15, whereby one of the divided steering shafts 10A is moved in the axial direction. Moving. The rotation of the output shaft 6Ba of the other steered motor 6B is transmitted to the ball nut 18B via the output gear 19B and the input gear 20B of the second output transmission mechanism 16, whereby the other divided steering shaft 10B is moved in the axial direction. Moving. When both the turning motors 6A and 6B are rotated in the same direction, the two divided steering shafts 10A and 10B are moved in the same direction by the same amount, and the wheels 13 are steered. Further, when both the steered motors 6A and 6B are rotated in the opposite directions, the two divided steering shafts 10A and 10B are moved in the opposite directions by the same amount, and the toe angle of the wheel 13 is adjusted. The drive control including the rotation direction of both the steering motors 6A and 6B is performed by the steering control unit 5a of the ECU 5. The steering control unit 5a can independently control both the steering motors 6A and 6B.

  The output shafts 6Aa and 6Ba of the both steering motors 6A and 6B are coupled to each other via a sliding screw mechanism 24. The sliding screw mechanism 24 includes a screw shaft portion 22A formed on the output shaft 6Aa of one steered motor 6A, a screw shaft portion 22B formed on the output shaft 6Ba of the other steered motor 6B, and both screw shaft portions. 22A and 22B are composed of a sliding screw nut 17 that is in sliding contact and screwed together. The screw shaft portions 22A and 22B have opposite threaded grooves, and the pair of left and right screw holes 17a and 17b of the sliding screw nut 17 into which the screw shaft portions 22A and 22B are screwed are respectively connected to the screw shaft portions 22A. , 22B corresponding to the screw grooves are opposite to each other. Both screw holes 17a, 17b are on the same axis, and the leads of the screw grooves are the same.

  The output shafts 6Aa and 6Ba of the steering motors 6A and 6B are respectively provided with reverse input blocking clutch mechanisms 23A and 23B for blocking the rotation transmission from the output shafts 6Aa and 6Ba to the motor rotor (not shown). .

The operation of the above configuration will be described. In the sliding screw mechanism 24, since the screw shaft portions 22A and 22B of the left and right output shafts 6Aa and 6Ba are screwed in sliding contact with the pair of left and right screw holes 17a and 17b which are reversely threaded, Perform the action. When both screw shaft portions 22A and 22B are rotated in the same direction at the same angular velocity, both screw shaft portions 22A and 22B are integrated with the sliding screw nut 17 and rotated at the same angular velocity. When both screw shaft portions 22A and 22B are rotated in the opposite direction at the same angular velocity, the sliding screw nut 17 moves to the left and right.
When only one of the screw shaft portions 22A and 22B is rotated, the sliding screw mechanism 24 has low reverse transmission efficiency, that is, the axial movement of the sliding screw nut 17 is converted into the rotation of the screw shaft portions 22A and 22B. Since the transmission efficiency is low, the sliding screw nut 17 cannot move in the axial direction with respect to the screw shaft portions 22A and 22B on the motor stop side, and rotates integrally with the screw shaft portions 22A and 22B on the rotation side. The rotation is transmitted to the screw shaft portions 22A and 22B on the motor lowering side via the.

  The sliding screw mechanism 24 having such an action is used to connect the output shafts 6Aa and 6Ba of the both turning motors 6A and 6B, and the rotation of the output shafts 6Aa and 6Ba of the respective turning motors 6A and 6B is independently performed. Since the left and right output transmission mechanisms 15 and 16 that transmit to the respective divided steering shafts 10A and 10B are provided, the following actions are obtained by the operations of the steering motors 6A and 6B.

  The left and right steered motors 6A and 6B can be controlled independently. When the left and right steered motors 6A and 6B are rotated in the same direction at the same angular velocity, the divided steering shafts are provided via the output transmission mechanisms 15 and 16. 10A and 10B move in the same direction by the same amount. Thereby, the whole steering shaft 10 moves to the left and right, and the steering is performed. At this time, the output shafts 6Aa and 6Ba of the left and right steered motors 6A and 6B are coupled by the sliding screw mechanism 24. As described above, the sliding screw mechanism 24 is configured such that both screw shaft portions 22A and 22B slide. The screw nut 17 rotates together with the same angular velocity. Therefore, the sliding screw mechanism 24 does not become an obstacle to the rotation of both the output shafts 6Aa and 6Ba, and does not become an obstacle to turning.

  When the left and right steered motors 6A and 6B are rotated in the reverse direction, the divided steering shafts 10A and 10B move in the opposite directions via the output transmission mechanisms 15 and 16, respectively. Therefore, the total length of the steering shaft 10 is changed, and the toe angle can be adjusted. At this time, the output shafts 6Aa and 6Ba of the left and right steered motors 6A and 6B are coupled by the sliding screw mechanism 24. The sliding screw mechanism 24 reverses both screw shaft portions 22A and 22B as described above. By rotating in the direction, the sliding screw nut 17 moves left and right. Therefore, the sliding screw mechanism 24 does not hinder the reverse rotation of the output shafts 6Aa and 6Ba, and does not hinder the toe angle adjustment.

  When one of the left and right steered motors 6A, 6B fails, only the other steered motor 6A, 6B rotates. At this time, since they are coupled by the slide screw mechanism 24 having the above-described action, the rotation of the output shafts 6Aa and 6Ba of the rotation-side steering motors 6A and 6B is caused by the rotation of the output shafts of the failure-side steering motors 6A and 6B Rotation can be transmitted to 6Aa and 6Ba, and both wheels can be steered. Further, when the rotors of the failed steering motors 6A and 6B are fixed by the action of the reverse input cutoff clutch mechanisms 23A and 23B, the output shafts 6Aa and 6Ba can be rotated, and the sliding screw mechanism 24 is interposed. Thus, the rotation of the output shafts 6Aa and 6Ba transmitted to the output transmission mechanisms 15 and 16 can be performed and steered.

  When one of the steering motors 6A and 6B fails, the steering is performed with only one of the steering motors 6A and 6B, but the other of the one of the steering motors 6A and 6B at the time of the motor failure occurs. An alternative to the steering motors 6A and 6B is an operation performed when the vehicle is traveling. Therefore, the maximum generated torque is much smaller than the torque required during the stationary operation. Therefore, each of the two steered motors 6A and 6B may be smaller than the steered motor in the case where the steered motor is configured to steer.

  According to the steer-by-wire type steering device having this configuration, as described above, the fail-safe mechanism using the sliding screw mechanism 24 with low reverse transmission efficiency allows the steering motor 6A, 6B of either one to fail, Steering is possible without requiring mechanical or electrical switching. Also, the toe angle can be adjusted.

  In the above embodiment, the sliding screw mechanism 24 having the pair of reverse screws shown in FIG. 2 is used. However, the sliding screw mechanism 24 is not limited to the one shown in FIG. It must be a sliding screw nut that allows independent rotation of each screw shaft and has the function of transmitting the rotation to the other screw shaft when only one of the screw shafts is rotated. It ’s fine.

DESCRIPTION OF SYMBOLS 1 ... Steering wheel 2 ... Steering angle sensor 4 ... Steering reaction force motor 5 ... ECU
5a ... Steering controllers 6A, 6B ... Steering motors 6Aa, 6Ba ... Steering motor output shaft 10 ... Steering shafts 10A, 10B ... Split steering shafts 10Aa, 10Ba ... Ball screw shaft 15 ... First output transmission mechanism 16 ... second output transmission mechanism 17 ... sliding screw nuts 18A, 18B ... ball nuts 22A, 22B ... screw shaft portions 23A, 23B ... reverse input blocking clutch mechanism 24 ... sliding screw mechanism

Claims (9)

A steering wheel that is not mechanically connected to a steering shaft for turning, a steering angle sensor that detects a steering angle of the steering wheel, a steering reaction force motor that applies a reaction torque to the steering wheel, and the steering A steering motor that drives a shaft, a steering control unit that controls the steering reaction force motor and the steering motor, and based on a driving state detection signal including a steering angle signal detected by the steering angle sensor. In the steer-by-wire type steering device that controls the steering motor by the steering control unit,
The steering shaft is divided into two divided steering shafts for steering the left and right wheels, and two steering motors are provided for independently driving these two divided steering shafts via the left and right output transmission mechanisms, The output shaft of both steered motors is made up of a pair of screw shafts and sliding screw nuts, allowing independent rotation of each screw shaft and rotating only one of the screw shafts. Combined with a sliding screw mechanism that has the function of transmitting to the other screw shaft,
This sliding screw mechanism outputs the output of the turning motor on the rotational drive side by rotating the other turning motor in a state in which one of the turning motors has failed. A steer-by-wire type steering apparatus characterized in that the rotation of the shaft can be transmitted to the output shaft of the failed steering motor.   2. The sliding screw according to claim 1, wherein the sliding screw mechanism includes a pair of screw shaft portions of mutually opposite screws provided on both output shafts, and a pair of screw groove portions of mutually opposite screws screwed to the both screw shaft portions, respectively. Steer-by-wire steering device consisting of nuts.   3. The split steering shaft according to claim 1, wherein each of the divided steering shafts has a ball screw shaft portion in part, and the both output transmission mechanisms are respectively screwed into the ball screw shaft portions of the divided steering shafts. A ball nut, and the ball nut is rotated by rotation of the steering motor to advance and retract the divided steering shaft in the axial direction. A steer-by-wire steering device that can be steered and toe angle adjusted by moving in the axial direction.   4. The left and right output transmission mechanism according to claim 1, wherein the left and right output transmission mechanisms are configured to move the split steering shafts in the same direction by rotating the steering motors in the same direction. Steer-by-wire steering device.   5. The left and right output transmission mechanisms according to claim 1, wherein the left and right output transmission mechanisms are configured to move the split steering shafts in opposite directions by rotating the steering motors in opposite directions. Steer-by-ear type steering device.   6. The sliding screw mechanism according to claim 1, wherein the sliding screw mechanism is configured such that the sliding screw nut is integrated with an output shaft of the steering motor when the both steering motors are rotated in the same direction at the same angular velocity. A steer-by-wire steering device that rotates at the same angular velocity.   7. The steer-by-wire according to claim 1, wherein the sliding screw mechanism moves the sliding screw nut to the left and right when the two steered motors are rotated in the opposite directions at the same angular velocity. Type steering device.   In any one of Claims 1 thru | or 7, when the said sliding screw mechanism rotates only one side of the both of the steering motors, the reverse transmission efficiency of the sliding screw nut is low. A steer-by-wire steering device that transmits rotation to the output shaft of the other steering motor.   9. The steer according to claim 1, wherein each of the steered motors includes a reverse input blocking clutch mechanism that blocks rotation transmission from the output shaft to the motor rotor between the motor rotor and the output shaft. By-wire steering device.

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