JP2007015666A - Steering device for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a steering device for a vehicle equipped with a steering actuator having simple constitution operating the steering mechanism for steering. <P>SOLUTION: The steering device for the vehicle is equipped with a grasping solenoid 45 and a grasping member 48 which grasp or release the grasping the midway of a steering shaft 12 of a steering actuator 4 adding a moving force to the steering shaft 12 moving in the axial length direction for steering the vehicle to the right and left, a left solenoid 40 and a right solenoid 41 moving them to the both direction of the axial length direction of the steering shaft 12, and neutral springs 46, 47 which energize the grasping solenoid 45 from both sides of the right and left, and locate it at the predetermined neutral position. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a vehicle steering apparatus for steering a vehicle left and right in accordance with an operation of a steering member such as a steering wheel made by a driver.

  As a vehicle steering device, in recent years, a steering member such as a steering wheel inside a vehicle interior is mechanically separated from a steering mechanism outside the vehicle interior, and based on the detection result of the operation direction and operation amount of the steering member. A so-called steer-by-wire type steering device is being developed which is configured to drive and control a steering actuator attached to a steering mechanism and apply steering force to the steering mechanism to perform steering.

  This type of vehicle steering apparatus can freely change the correspondence between the operation amount of the steering member and the operation amount of the steering mechanism without being subjected to mechanical restrictions. It has the advantage of being able to flexibly respond to the change control of the steering characteristics according to the driving condition, such as the presence or absence of deceleration, and it is easy to cope with automatic driving systems (ITS, AHS, etc.) that are being developed in recent years. It has the advantage of being, and has attracted attention as being useful for the development of automotive technology. As a steering actuator attached to the steering mechanism, a motor (steering motor) is generally used in consideration of ease of control, and rotation of the steering motor is applied to a steering shaft provided in the steering mechanism. In other words, the steering shaft is moved in both directions in the axial direction to realize left and right steering.

On the other hand, in such a steer-by-wire type steering device, as described above, since the steering member is mechanically separated from the steering mechanism, a fail-safe countermeasure for the steering motor is indispensable. At the same time, a fail-safe motor is attached to the steering mechanism, and this motor is driven when an abnormality occurs in the steering motor so as to perform auxiliary steering in an emergency (see, for example, Patent Document 1).
Japanese Patent Laid-Open No. 10-218000

  However, the vehicle steering apparatus configured as described above requires a transmission system and a control system similar to the steering motor in order to enable steering by a fail-safe motor used only when an abnormality occurs. There is a problem that the device configuration becomes complicated.

  In the vehicle steering device disclosed in Patent Document 1, the fail-safe motor is driven not only during an abnormality but also during normal steering to assist steering by the operation of the steering motor. Although the device configuration is simplified by downsizing, complication of the device configuration due to the installation of a fail-safe motor, transmission means from the motor to the steering mechanism, which is not necessary for normal steering, can be avoided. Absent.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a vehicle steering apparatus including a steering actuator having a simple configuration that operates a steering mechanism for steering.

  A vehicle steering apparatus according to a first aspect of the present invention is a steering shaft that moves in the axial direction for left-right steering of a vehicle, and a steering that operates according to an operation of a steering member and applies a moving force to the steering shaft. In the vehicle steering apparatus including the actuator, the steering actuator moves the gripping means in both axial directions of the steering shaft and gripping means for gripping or releasing the middle of the steering shaft. And a pair of left and right moving means, and an elastic body that urges the gripping means from the left and right sides and positions the gripping means at a predetermined neutral position.

  The vehicle steering apparatus according to the second invention of the present invention is characterized in that the gripping means and the moving means in the first invention are constituted by solenoids.

  In the vehicle steering apparatus according to the first aspect of the present invention, the steering shaft is gripped by the gripping means in the neutral position, and the steering shaft is moved in the axial length direction together with the gripping means by the operation of the moving means in this state. Steering can be performed with a simple configuration that does not require a steering motor and transmission means for converting the rotation of the motor to transmit it to the steering shaft.

  Further, in the vehicle steering apparatus according to the second invention, since the gripping means and the moving means are constituted by solenoids, the respective operations can be easily performed by switching between excitation and demagnetization of these solenoids. The invention has an excellent effect.

  Hereinafter, the present invention will be described in detail with reference to the drawings illustrating embodiments thereof. FIG. 1 is a schematic diagram showing the overall configuration of a vehicle steering apparatus according to the present invention, and a steering mechanism 1 for steering a pair of steering wheels 10 and 10 disposed on the left and right of a vehicle body (not shown), The steering mechanism is configured as a steer-by-wire type steering apparatus including a steering wheel (steering member) 2 that is mechanically separated from the steering mechanism 1 and is rotated for steering.

  The steering mechanism 1 includes a steering shaft 12 that is supported in an axially movable manner inside a cylindrical housing 11 that extends in the left-right direction of the vehicle body. Both ends of 12 are connected to knuckle arms 13 and 13 of steering wheels 10 and 10 via separate tie rods 14 and 14, respectively, and the steering shaft 12 moves in both directions via tie rods 14 and 14. The knuckle arms 13 and 13 are pushed and pulled to steer the wheels 10 and 10 left and right.

  The steering mechanism 1 configured as described above is provided with a steering motor 3 for applying a moving force to the steering shaft 12 to perform the above-described steering. The illustrated steering motor 3 includes a cylindrical rotor that rotates coaxially with the steering shaft 12 and a stator that surrounds the outside of the rotor, inside a motor housing 15 that has an enlarged middle portion of the housing 11. The rotation of the rotor in response to energization of the stator is transmitted to the steering shaft 12 via the ball screw mechanism 30 connected to one side, and the steering shaft 12 is pivoted. It is configured to move in the long direction.

  Further, the steering mechanism 1 is provided with a steering actuator 4, which is a feature of the present invention, arranged side by side on the steering motor 3, and auxiliary steering by movement of the steering shaft 12 is also performed by the operation of the steering actuator 4. Configured to do. FIG. 2 is a schematic diagram showing the configuration of the steering actuator 4.

  As shown in the figure, the steering actuator 4 includes a left solenoid 40 and a right solenoid 41 fixed to the left and right sides of a window hole 16 that opens in the outer wall of the housing 11 that supports the steering shaft 12. The left solenoid 40 and the right solenoid 41 are provided so as to project toward opposite sides of the solenoid 40 and have an output end that moves forward and backward substantially in parallel with the steering shaft 12. , 43 are connected to a support base 44 of a gripping solenoid 45.

  The left solenoid 40 and the right solenoid 41 are selectively excited in accordance with an excitation signal given from the outside, and apply a tensile force to the steering springs 42 and 43 connected to the respective output ends. The spring 44 is configured to move the support base 44 of the gripping solenoid 45 to the left and right.

  The window hole 16 that opens between the left solenoid 40 and the right solenoid 41 is a long hole having an appropriate length between the solenoids 40 and 41, and both ends of the window hole 16 and the support base 44 A neutral spring 46, 47 is interposed between the support base 44 and the gripping solenoid 45 supported by the support base 44 when the left solenoid 40 and the right solenoid 41 are in an inoperative state. The spring force of the springs 46 and 47 is configured to be positioned at a substantially central position of the window hole 16, that is, at a neutral position of the approximate center of the left solenoid 40 and the right solenoid 41.

  The gripping solenoid 45 has an output end that moves forward and backward in a direction substantially orthogonal to the steering shaft 12, and this output end extends through the window hole 16 into the housing 11 and is halfway through the steering shaft 12. When the gripping solenoid 45 is excited in accordance with an excitation signal given from the outside, the gripping member 48 connected to the output end corresponds to the corresponding position of the steering shaft 12. Is configured to grip.

  In the steering actuator 4 configured as described above, steering is performed by moving the steering shaft 12 in both the left and right directions by a combination of selective excitation of the left solenoid 40 and right solenoid 41 and excitation of the gripping solenoid 45. be able to. 3 and 4 are explanatory diagrams of the operation of the steering actuator 4 and show a steering state in the left direction.

  In this case, first, as shown in FIG. 3, the gripping solenoid 45 is excited and the middle of the steering shaft 12 is gripped by the operation of the gripping member 48 connected to the output end. Next, the left solenoid 40 is excited to apply a tensile force to the steering spring 42 at the output end. As a result, the steering spring 42 extends as shown in FIG. 4, and the support 44 of the gripping solenoid 45 is pulled leftward by the spring force of the steering spring 42, and the gripping member 48 at the output end of the gripping solenoid 45. The steering shaft 12 gripped by is moved to the left as indicated by white arrows in the figure. Thereafter, the gripping solenoid 45 is demagnetized to release the grip of the steering shaft 12 by the gripping member 48, and when the left solenoid 40 is also demagnetized, the gripping solenoid 45 released from the restraint by the gripping member 48 is 2 return to the neutral position shown in FIG. 2 by the elastic return of the neutral springs 46 and 47 on both sides of the support 44.

  In this way, the steering shaft 12 is moved to the left in the operation stroke of the left solenoid 40 by the excitation of the gripping solenoid 45 and the left solenoid 40, and is gripped by the demagnetization of the gripping solenoid 45 and the left solenoid 40 thereafter. Since the holding solenoid 45 and the support base 44 are returned to the neutral position, the steering shaft 12 can be continuously moved leftward by repeating the above excitation and demagnetization, and leftward steering can be performed according to this movement. it can. Steering in the right direction is realized by operating the right solenoid 41 instead of the left solenoid 40.

  Thus, the steering angle realized in the steering mechanism 1 by the operation of the steering motor 3 or the steering actuator 4 is an actual steering angle sensor configured to detect the displacement of the connecting portion between the steering shaft 12 and the tie rod 14 on one side. 17 is detected and given to the steering control unit 5. Further, a tie rod axial force sensor 18 for detecting an axial force acting in the axial direction is attached to the tie rod 14 on one side, and this detection result is a steering reaction force that is actually applied to the steering mechanism 1 with steering. Is given to the steering control unit 5 as a signal indicating.

  The steering wheel 2 is fitted and fixed to the upper end portion of the column shaft 20 serving as a rotation shaft, and is disposed so as to face the driver inside a passenger compartment (not shown). The column shaft 20 is rotatably supported inside a column housing 21 that is fixedly supported at an appropriate part of the vehicle body. A reaction force motor 6 is mounted on the outer side of the middle part of the column housing 21 with an axis substantially orthogonal thereto, and is transmitted to the column shaft 20 inside the column housing 21 via a speed reduction mechanism such as a worm gear mechanism. Thus, the rotational force of the reaction force motor 6 is applied to the column shaft 20 under deceleration by the speed reduction mechanism, and the steering reaction force is applied to the steering wheel 2 fixed to the upper end of the column shaft 20. It is configured.

  The operating angle of the steering wheel 2 that is rotated and operated against the steering reaction force added in this way is detected by a steering angle sensor 22 attached in the middle of the column housing 21 and is given to the steering control unit 5. ing. Further, the steering control unit 5 is provided with a detection result of a driving state that affects steering such as a vehicle speed, a yaw rate, a lateral acceleration, and a longitudinal acceleration from a driving state sensor 23 installed in each part of the vehicle.

  The steering control unit 5 is configured as an electronic control unit including a CPU, a ROM, and a RAM, and the output of the steering control unit 5 is a reaction that is attached to the steering motor 3 and the steering wheel 2 attached to the steering mechanism 1. It is given to the force motor 6 through separate drive circuits (not shown), and is further given to a steering actuator 4 attached to the steering mechanism 1. As will be described below, when the steering actuator 4 is used for fail-safe when an abnormality occurs in the steering motor 3, the steering actuator 4 is controlled by the steering control unit 5 including the CPU, ROM and RAM as described above. It is not always necessary to perform this operation, but by a control means having a function capable of outputting an electric signal via a simple sequence circuit that drives a solenoid from an input of an electric pulse signal that can determine the operation direction and the operation angle of the steering wheel 2 Can be done.

  The steering control unit 5 issues an operation command to the steering motor 3 to perform steering in accordance with the rotation operation of the steering wheel 2, the steering control operation for driving the steering motor 3, and the reaction force actually applied to the steering mechanism 1. In order to let the driver operating the steering wheel 2 experience, an operation command is issued to the reaction force motor 6 and a reaction force control operation for driving the reaction force motor 6 is performed.

  As is well known, the steering control operation of the steering controller 5 for the steering motor 3 calculates the target steering angle by multiplying the operation angle of the steering wheel 2 detected by the steering angle sensor 22 by the correction coefficient, and this target The procedure for driving the steering motor 3 according to the magnitude and direction of the deviation (steering angle deviation) between the steering angle and the actual steering angle of the left and right steering wheels 10 and 10 detected by the actual steering angle sensor 17 Done. As a result, the steering mechanism 1 operates in accordance with the operation of the steering wheel 2, and the steering wheels 10, 10 are steered.

  The correction coefficient used for calculating the target rudder angle is small as the vehicle speed increases, for example, according to the traveling state detected by the traveling state sensor 23, and is about the degree of turning of the vehicle determined by the yaw rate and lateral acceleration. It is selected so that it becomes smaller as the increase increases. As a result, the target rudder angle becomes small during high-speed running, becomes large during low-speed running, and becomes smaller during cornering as the vehicle turns suddenly. The steering control operation described above is performed based on such a target rudder angle. By performing the above, a steering characteristic corresponding to the traveling state can be obtained.

  During such a steering control operation, the steering actuator 4 is in the state shown in FIG. 2, and the movement of the steering shaft 12 by the drive of the steering motor 3 and the steering by this movement are not hindered by the steering actuator 4. Can be implemented.

  As is well known, the reaction force control operation of the steering control unit 5 for the reaction force motor 6 determines the actual reaction force applied to the steering mechanism 1 based on the input from the tie rod axial force sensor 18, as known. A target reaction force to be applied to the steering wheel 2 is calculated by multiplying the reaction force by a correction coefficient, a driving current corresponding to the target reaction force is supplied to the reaction force motor 6, and the rotational force of the reaction force motor 6 is calculated as a column. In addition to the steering wheel 2 via the shaft 20, the operation is performed so that the driver operating the steering wheel 2 can experience it.

  The traveling state detected by the traveling state sensor 23 is also used for selecting a correction coefficient in the reaction force control operation described above, and this correction coefficient increases, for example, as the vehicle speed and the degree of turning increase. It is selected so as to increase according to an increase in the degree of deceleration required by the acceleration. As a result, the target reaction force becomes larger during high-speed traveling, sudden turning, and deceleration, and the desired steering for the driver who operates the steering wheel 2 by controlling the reaction force motor 6 based on the target reaction force. You can feel the feeling.

  Further, the steering control unit 5 determines whether or not there is an abnormality in the steering motor 3 to be controlled during the steering control operation performed as described above. This determination is made, for example, by monitoring the change in the detected value of the actual steering angle sensor 17 given as the feedback value of the steering angle change caused by this driving during the driving of the steering motor 3, and determining that there is an abnormality. In this case, the steering control unit 5 stops the steering control operation with respect to the steering motor 3, performs the fail-safe operation in which the steering actuator 4 is controlled, and the steering is performed by the operation of the steering actuator 4.

  In this fail-safe operation, the operation direction of the steering wheel 2 performed by the driver for steering is obtained from the detected value of the operation angle of the steering wheel 2 by the steering angle sensor 22, and the steering actuator 4 operates according to this direction. This is done to issue a command.

  For example, when the operation direction of the steering wheel 2 is the left direction, the steering actuator 4 repeatedly executes excitation and demagnetization of the left solenoid 40 and the gripping solenoid 45 by the operation command from the steering control unit 5, thereby steering The shaft 12 is moved, and a predetermined amount of steering is performed in the left direction. When the operation direction of the steering wheel 2 is the right direction, exactly the same steering is performed according to the operation command given from the steering control unit 5 for the right solenoid 41 and the gripping solenoid 45 of the operation actuator 4.

  By such a fail-safe operation, emergency steering can be performed when the steering motor 3 is abnormal. Since this steering is performed by the operation of the steering actuator 4 simply configured as shown in FIG. 2, a motor dedicated to fail-safe operation and transmission means from the motor become unnecessary, and the configuration of the vehicle steering apparatus is simplified. Can be

  Note that the steering performed by the steering actuator 4 as described above is as simple as steering the steering wheels 10 and 10 in the direction of operation of the steering wheel 2, but only to move the vehicle to a safe position. Can be run without hindrance. In addition, when the operation shifts to the fail-safe operation, it is desirable that the steering control unit 5 performs an appropriate alarm operation such as generation of an alarm sound or lighting of an alarm lamp so as to notify the driver of the occurrence of an abnormality.

1 is a schematic diagram showing an overall configuration of a vehicle steering apparatus according to the present invention. It is a schematic diagram which shows the structure of a steering actuator. It is operation | movement explanatory drawing of a steering actuator. It is operation | movement explanatory drawing of a steering actuator.

Explanation of symbols

2 Steering wheel (steering member)
4 Steering actuator
12 Steering shaft
40 Left solenoid (moving means)
41 Right solenoid (moving means)
45 Gripping solenoid (gripping means)
46, 47 Neutral spring (elastic body)
48 Gripping member (gripping means)

Claims (2)

In a vehicle steering apparatus comprising: a steering shaft that moves in the axial length direction for left-right steering of a vehicle; and a steering actuator that operates according to an operation of a steering member and applies a moving force to the steering shaft, the steering actuator includes: ,
Gripping means for gripping or releasing the middle of the steering shaft;
A pair of left and right moving means for moving the gripping means in both axial directions of the steering shaft;
A vehicle steering apparatus comprising: an elastic body that urges the gripping means from the left and right sides and positions the gripping means at a predetermined neutral position.   The vehicle steering apparatus according to claim 1, wherein the gripping means and the moving means are constituted by solenoids.

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