JP3586782B2 - Vehicle steering system - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an improvement in a vehicle steering system in which a steering unit and a steering mechanism are mechanically disconnected from each other.
[0002]
[Prior art]
A vehicle steering system (hereinafter referred to as a linkless steering) in which a steering means including a steering wheel and a steering mechanism are mechanically disconnected from each other is provided in a steering mechanism in the same manner as a steering assist actuator in a power steering mechanism. An electric motor as a steering actuator is provided, and the electric motor is driven based on a detection result of a steering angle of a steering wheel, whereby steering according to the steering of the steering wheel is performed. ing.
[0003]
The steering wheel is rotatably held at an appropriate portion of the vehicle body by a rotating shaft projecting downward. A movement conversion mechanism comprising a combination of a worm gear and a pinion gear is provided in the middle of the rotating shaft, and a reaction actuator using an electric motor is connected to the movement conversion mechanism via an electromagnetic clutch. The reaction force actuator has a function of applying a force (reaction force) in a direction opposite to the steering direction, which becomes large or small according to the level of the vehicle speed and the magnitude of the steering angle of the steering wheel, to the rotating shaft.
[0004]
In addition, a torsion screw having one end fixed to an appropriate portion of the vehicle body is coaxially connected to the lower end of the rotating shaft. This twisting is for applying a certain amount of reaction force to the rotating shaft even when the reaction force actuator breaks down and the electromagnetic clutch is forcibly disengaged.
[0005]
[Problems to be solved by the invention]
By the way, in a conventional connection type vehicle steering device, for example, when parking on a slope, the wheels may be steered to the road shoulder side and pressed against the curb to prevent the wheels from moving. Is connected via a steering mechanism and a motion conversion mechanism such as a rack-and-pinion mechanism, the driver releases his / her hand from the steering wheel in a steered state and turns off a key switch for stopping the engine. The steering wheel does not rotate from a state in which the steering wheel coincides with the turning direction of the wheel.
[0006]
However, in the linkless steering, similarly, when the driver releases his / her hand from the steering wheel in a steering state during parking and turns off the key switch, the electromagnetic clutch is disengaged, and the elastic force of the twisting spring is accompanied. Thus, the steering wheel is returned to the neutral position. Then, when the engine is restarted, there is a problem that the rotational position of the steering wheel does not match the turning direction of the wheel.
[0007]
The present invention has been made in view of such circumstances, and detects the actual direction of a wheel based on the steering angle of a steering mechanism, and rotates the steering wheel so as to match the direction of the wheel when the vehicle starts. It is an object to provide a vehicle steering device to be driven.
[0008]
[Means for Solving the Problems]
A vehicle steering system according to the present invention includes a steering unit mechanically disconnected from a steering mechanism of a vehicle, a steering angle detection unit that detects a steering angle of the steering unit, and a detection result of the steering angle detection unit. A steering angle detecting device for detecting a steering angle of the steering mechanism in a vehicle steering system including an actuator for applying a steering force to the steering mechanism in response thereto, and means for urging the steering means in a neutral direction. Means for rotating the steering means so that the steering angle coincides with a position corresponding to the steering angle when the vehicle is started.
[0009]
According to the steering apparatus for a vehicle according to the present invention, the steering angle detecting means detects the actual steering angle of the wheel, and shifts the steering means returned to the neutral position to a rotation position corresponding to the steering angle when the vehicle starts. Since the driving is performed, the steering angle and the steering angle can be brought into the same state.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in detail with reference to the drawings showing the embodiments. FIG. 1 is a block diagram showing the overall configuration of a vehicle steering system according to the present invention.
[0011]
In the vehicle steering system according to the present invention, a steering mechanism 1 for causing a pair of steering wheels 10, 10 arranged on the left and right sides of a vehicle body to perform a steering operation, and the steering mechanism 1 is mechanically mounted. A steering wheel 2, which is a non-coupled steering means, a reaction force actuator 3 for applying a reaction force to the steering wheel 2, and a steering control unit 4 using a microprocessor, according to the steering of the steering wheel 2. By the operation of the steering control unit 4, a steering motor 5 as an actuator disposed in the steering mechanism 1 is driven via a drive circuit 5 a to operate the steering mechanism 1.
[0012]
The steering mechanism 1 includes two tie rods, which are provided in the left and right direction of the vehicle body and move in the axial direction of the steering shaft 11, and knuckle arms 12 and 12 that support the left and right wheels 10 and 10, respectively. The knuckle arms 12, 12 are pushed and pulled via the tie rods 13, by the movement of the steering shaft 11 in both the left and right directions, and the wheels 10, 10 are steered right and left. The steering is performed by converting the rotation of the steering motor 5 provided in the middle of the steering shaft 11 into the axial movement of the steering shaft 11 by an appropriate motion converting mechanism.
[0013]
A tie rod displacement sensor 15 (a rudder) composed of a linear sliding type potentiometer straddles a connecting portion between one tie rod 13 and the steering shaft 11 and a steering shaft housing 14 which slidably supports the steering shaft 11 in the axial direction. Angle detecting means) is provided to detect the axial displacement of the tie rod 13 with respect to the steering shaft housing 14. The detection result is provided to the steering control unit 4, and is converted into a steering angle by performing a predetermined calculation.
[0014]
The steering wheel 2 is rotatably held at an appropriate part of the vehicle body by a rotating shaft 30 projecting downward. A steering angle sensor 33 is provided in the middle of the rotating shaft 30 to detect the steering angle (steering angle) of the steering wheel 2 including its direction, and the detection result is given to the steering control unit 4. Have been.
[0015]
Above the steering angle sensor 33 on the rotating shaft 30, a motion conversion mechanism comprising a combination of a worm gear and a pinion gear is provided, and a reaction force actuator 3 using an electric motor is connected to the motion conversion mechanism via an electromagnetic clutch 3b. A motor provided at an appropriate portion of a vehicle body (not shown) and using a rotation speed sensor for detecting the rotation speed of a front wheel or a rear wheel and corresponding to an output from a vehicle speed sensor 6 and an output from the steering angle sensor 33. When a current is applied to the reaction force actuator 3 via the drive circuit 3a, a force (reaction force) is applied to the rotating shaft 30 in a direction opposite to the steering direction which increases or decreases according to the vehicle speed and the steering angle. Has the effect of adding. Therefore, it is necessary to apply a steering torque against the reaction force generated by the reaction force actuator 3 to the rotational steering of the steering wheel 2. The steering torque applied to the steering wheel 2 is detected by a torque sensor 32 attached to the rotating shaft 30, and the detection result is given to the steering control unit 4.
[0016]
A torsion spring 31 having one end fixed to an appropriate part of the vehicle body is coaxially connected to the lower end of the rotary shaft 30. The torsion spring 31 applies a certain amount of reaction force to the rotating shaft 30 even when the reaction force actuator 3 breaks down and the electromagnetic clutch 3b is forcibly disconnected.
[0017]
As described above, the steering control unit 4 provides the actually generated steering state as an input from the tie rod displacement sensor 15 and the steering state of the steering wheel 2 as an input from the steering angle sensor 33. The magnitude and direction of the reaction force applied to the steering wheel 2 are given as inputs from the torque sensor 32, respectively.
[0018]
On the other hand, the output of the steering control unit 4 is transmitted to the reaction force actuator 3 for applying a reaction force to the steering wheel 2 and the steering motor 5 for causing the steering mechanism 1 to perform a steering operation, as described above. The driving force is supplied via other drive circuits 3a and 5a, and the reaction force actuator 3 and the steering motor 5 perform different operations in response to operation signals from the steering control unit 4.
[0019]
In the vehicle steering system having such a configuration, the steering control unit 4 calculates a target steering angle based on the steering angle θ of the steering wheel 2 and the vehicle speed from the vehicle speed sensor 6, and calculates the target steering angle and the tie rod displacement sensor 15. Is controlled based on the deviation from the actual steering angle of the steering mechanism 1 calculated from the output of the steering motor 5 so that the steering angle of the steering mechanism 1 matches the target steering angle.
[0020]
On the other hand, when the engine is started, the steering control unit 4 performs the reverse operation, and based on the steering angle θ and the steering angle given at the time of starting, the rotation of the steering wheel 2 according to the steering angle. The position, that is, the target steering angle Θ is calculated, and control for driving the reaction force actuator 3 is performed so that the steering angle θ matches the target steering angle Θ.
[0021]
FIG. 2 is a flowchart showing the operation of the steering control unit 4. The state of the key switch for starting the engine is confirmed (step 1). If the key switch is on, the outputs of the steering angle sensor 33 and the tie rod displacement sensor 15 are first read (step 2). Next, a steering angle is calculated from the read tie rod displacement, and a target steering angle た corresponding to the steering angle is calculated (step 3). Then, the target steering angle Θ is compared with the detected steering angle θ (step 4), and if different, an operation signal for supplying a predetermined motor current to the reaction force actuator 3 is given to the drive circuit 3a (step 5). Steps 1 to 3 are repeated, and when the steering angle θ coincides with the target steering angle 表示, the driver is notified of the possibility of starting by a display means such as a lamp on a console panel (not shown) (step 6), and the operation is performed. finish. The operation is also terminated when the key switch is turned off during the operation.
[0022]
It is needless to say that the reaction force actuator 3 applies a larger rotating force to the rotary shaft 30 than the spring 31 when the steering wheel 2 is twisted in order to return the rotational position of the steering wheel 2 to the target steering angle Θ.
[0023]
In the vehicle steering system configured as described above, the key switch is turned off when the vehicle is steered, and the steering wheel 2 is returned to the neutral position by the spring 31 if the driver twists after releasing the hand from the steering wheel 2. However, the steering angle of the steering wheel 2 can be matched with the steering angle of the steering mechanism 1 at the time of starting.
[0024]
The above embodiment shows an example of the vehicle steering system according to the present invention, and does not limit the configuration of the reaction force actuator 3. Further, as the steering means, instead of the steering wheel 2, a lever is used. Needless to say, other steering means such as a joystick can be used.
[0025]
【The invention's effect】
As described in detail above, in the vehicle steering system according to the present invention, the steering means returned to the neutral position by the means for biasing in the neutral direction is rotated so as to match the actual wheel direction at the time of starting. Therefore, the present invention has an excellent effect that the vehicle can be started in a direction unexpected by the driver without starting.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of a vehicle steering system according to the present invention.
FIG. 2 is a flowchart illustrating an operation content of a steering control unit.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Steering mechanism 2 Steering wheel 3 Reaction force actuator 4 Steering control unit 5 Steering motor 15 Tie rod displacement sensor 30 Rotating shaft 31 Torsion spring 32 Torque sensor 33 Steering angle sensor

Claims (1)

Steering means mechanically uncoupled from the steering mechanism of the vehicle, steering angle detection means for detecting a steering angle of the steering means, and a steering force applied to the steering mechanism in accordance with the detection result of the steering angle detection means A steering angle detecting means for detecting a steering angle of the steering mechanism; and a steering angle detecting means for detecting a steering angle of the steering mechanism when the vehicle is started. Means for rotating the steering means so as to match the steering angle with a position corresponding to the steering angle.

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