JP2003112652A - Steering device for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a steering device for a vehicle capable of preventing swing- back when reducing a steering angle of the vehicle without requiring complicated control and without increasing burden of tires, having no influence on a danger avoiding steering. SOLUTION: A ratio of manipulated amount of an operating member H and steering amount of a front wheel is changed according to a variable showing a traveling state by controlling a motor-driven actuator 39 when transmitting the movement of the motor-driven actuator 39 to the front wheel so that a steering angle changes. When the operating member H is operated to reduce the steering angle, the motor-driven actuator 39 is controlled so that the steering speed of the front wheel is limited to below an upper limit value set to suppress swing-back in the case of a swing-back suppression requiring state in which the speed is above a set value and operating speed of the operating member H is above the set value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle in which a ratio between an operation amount of an operation member and a steered amount of front wheels can be changed according to a variable representing a running state of the vehicle, after a steering angle is increased in one direction. The present invention relates to a steering device for a vehicle, which prevents swingback, which is yaw motion in the other direction of the vehicle when the steering angle of the vehicle is reduced.

[0002]

2. Description of the Related Art When the vehicle speed and the operating speed of a steering wheel are above a certain level, yaw motion of the vehicle in the other direction, that is, rolling back, occurs when the steering angle decreases after the steering angle increases in one direction. The occurrence of this swing back is shown in FIG.
When the steering angle θ of the front wheels increases in one direction with the passage of time t and then decreases for straight-back return as indicated by the solid line in (1) of FIG. Further, the cornering force Ff of the front wheels changes substantially corresponding to the change of the steered angle θ of the front wheels, but as shown by the solid line in (3) of FIG. 10, the cornering force Fr of the rear wheels is changed.
Is due to the fact that it changes later than the change in the steered angle θ of the front wheels. That is, when the vehicle speed and the operation speed of the steering wheel are above a certain level, the cornering force Fr of the rear wheels becomes significantly larger than the cornering force Ff of the front wheels when the turning angle θ of the front wheels decreases. Then, as indicated by the solid line in (4) of FIG. 10, the yaw rate γ of the vehicle, which acts in the direction opposite to the steering direction of the front wheels at the time of returning straight, increases, so that swingback occurs.

It has been proposed to prevent such swing-back by using a vehicle steering system capable of changing the ratio between the steering wheel operation amount and the front wheel turning amount (Japanese Patent No. 2580865). In this conventional example, when operating the steering wheel to decrease the steering angle,
If the vehicle speed and the operation speed of the steering wheel are above a certain level, the steered angle of the front wheels is increased. As a result, the cornering force of the front wheels is increased before the rolling back occurs, and the yaw rate γ of the vehicle acting in the direction opposite to the steering direction of the front wheels is prevented from increasing.

[0004]

In the above-mentioned conventional example, since the steered angle of the front wheels is increased when the steering wheel is operated so that the steered angle is decreased, the front wheel is eliminated after the risk of rolling back is eliminated. It is necessary to reduce the steering angle of the wheel again, which complicates the control. Further, since the cornering force of the front wheels is increased, the load on the tire is increased.

An object of the present invention is to provide a vehicle steering system which can solve the above problems.

[0006]

According to the present invention, when the movement of the electric actuator is transmitted to the front wheels so that the steering angle changes, the electric actuator is controlled in accordance with a variable representing the running state of the vehicle. In a vehicle steering system capable of changing the ratio between the operation amount of the operation member and the steered amount of the front wheels in accordance with the variable, the vehicle speed is set to a set value when the operation member is operated to decrease the steering angle. If it is above and the operation speed of the operation member is equal to or more than the set value and is in the swing-back suppression necessary state, the steering speed of the front wheels is limited to the upper limit value or less set for the swing-back suppression. The electric actuator is controlled. A steering apparatus for a vehicle according to the present invention, an operation member, a means for detecting an operation amount of the operation member, an electric actuator, a control device for the electric actuator, and a movement of the electric actuator in which a steering angle is changed to a front wheel. Can be transmitted as
A vehicle including a sensor that detects at least the vehicle speed as a variable representing the traveling state of the vehicle, and the electric actuator is controlled so that the ratio of the operation amount of the operation member and the steered amount of the front wheels changes according to the detected variable. In the steering apparatus, means for obtaining an operation speed of the operation member, means for storing a set value of the vehicle speed and a set value of the operation speed of the operation member, which are criteria for judging whether or not the vehicle is in a swing-back suppression state. And when the operating member is operated so as to decrease the steering angle, whether the vehicle speed is equal to or higher than the stored set value and the operating speed of the operating member is equal to or larger than the stored set value, and whether or not the swing-back suppression is required. And a means for storing the set upper limit value of the turning speed of the front wheels for restraining the swing-back, and when the vehicle is in the state where the swing-back is required to be restrained, the operating member is adjusted so as to decrease the steering angle. Operate When preferably the electric actuator as the front wheel turning speed is limited below a set limit value stored it is controlled. Means for storing the set value of the vehicle speed and the set value of the operating speed of the operating member, and the stored installation value of the vehicle speed and the set value of the operating speed of the operating member,
It is preferable to satisfy the relationship that the set value of the operating speed of the operating member decreases as the set value of the vehicle speed increases. According to the present invention, since the steered speed of the front wheels is made slower than the set upper limit value in the case where the swing-back suppression is required, the decrease speed of the cornering force of the front wheels at the time of decreasing the steered angle of the front wheels also becomes slower. . As a result, the difference between the cornering force of the front wheels and the cornering force of the rear wheels when the steering angle is reduced becomes small, so that it is possible to prevent the cornering force of the rear wheels from becoming significantly larger than the cornering force of the front wheels. Therefore, it is possible to prevent the yaw rate of the vehicle acting in the direction opposite to the steering direction of the front wheels from increasing, and suppress the swing back. At this time, the control is simple because the turning speed of the front wheels only needs to be slower than the set upper limit value.
Further, since the cornering force of the front wheels does not increase more than necessary, the burden on the tire does not increase.

In the present invention, means for determining whether the vehicle is in the danger avoidance steering state is provided, and when the vehicle is in the danger avoidance steering state, the steering speed of the front wheels is limited to the set upper limit value or less. The control of the electric actuator is preferably released. In this case, when the vehicle is in the braking state and the operation speed of the operation member is equal to or larger than the second set value which is a reference value for determining whether or not the swing-back suppression is required, Is preferably determined to be in the danger avoidance steering state. As a result, when the vehicle is in the danger avoidance steering state, the turning speed of the front wheels does not slow down, so it is possible to prevent the steering angle change of the vehicle from being delayed.

An input shaft that rotates according to the operation of the operating member, an output shaft, a rotation transmission mechanism that transmits the rotation of the input shaft to the output shaft, and a steering angle that changes the rotation of the output shaft to the front wheels. It is preferable that a steering gear that transmits in this manner is provided, and the components of the rotation transmission mechanism are driven by the electric actuator so that the movement of the electric actuator is transmitted to the front wheels such that the steering angle changes. As a result, the present invention can be applied to a vehicle steering system in which the operating member and the front wheels are mechanically connected. The rotation transmission mechanism is configured by a planetary gear mechanism that holds a planetary gear that meshes with a sun gear and a ring gear by a carrier, and a first planetary gear element that is one of the sun gear, the ring gear, and the carrier is connected to the input shaft. A second planetary gear element that is not connected to the input shaft in the sun gear, ring gear, and carrier is connected to the output shaft, and is connected to the input / output shaft in the sun gear, ring gear, and carrier. The third planetary gear element, which is not present, is preferably rotationally driven by the electric actuator.

It is preferable that the movement of the electric actuator is transmitted to the front wheels such that the steering angle changes in accordance with the movement, without mechanically connecting the operating member to the front wheels. As a result, the present invention can be applied to a vehicle steering device that transmits the movement of the electric actuator to the front wheels such that the steering angle changes according to the movement without mechanically connecting the operating member to the front wheels.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A vehicle steering system 1 according to a first embodiment shown in FIG. 1 includes an input shaft 2 connected to a steering wheel (operating member) H. The input shaft 2 is supported by a housing 10 via bearings 7 and 8.

The rotation of the input shaft 2 in response to the operation of the steering wheel H is transmitted to the output shaft 11 via a planetary gear mechanism (rotation transmitting mechanism) 30. The output shaft 11 is arranged coaxially with the input shaft 2 with a gap, and is supported by the housing 10 via bearings 12 and 13. Its output shaft 11
Is transmitted to the front wheels so that the steering angle is changed by the steering gear. As the steering gear, known gears such as a rack and pinion type steering gear and a ball screw type steering gear can be used. Thus, the rotation of the input shaft 2 is transmitted to the output shaft 11 via the planetary gear mechanism 30, and the rotation of the output shaft 11 changes the steering angle.

The planetary gear mechanism 30 includes a planetary gear 33, which meshes with a sun gear 31 and a ring gear 32, on a carrier 3
Hold by 4. The sun gear 31 is connected to the end portion of the input shaft 2 so as to rotate together. The carrier 34 is connected to the output shaft 11 so as to rotate together. The ring gear 32 is fixed to a holder 36 surrounding the input shaft 2 via bolts 362. The holder 36 is supported via a bearing 9 by a tubular member 35 fixed to the housing 10 so as to surround the input shaft 2. Its holder 36
A worm wheel 37 is fitted on the outer circumference of the so as to rotate together. A worm 38 that meshes with the worm wheel 37 is supported by the housing 10. The worm 38 is driven by a motor (electric actuator) 39 attached to the housing 10. As a result, the ring gear 32, which is a component of the planetary gear mechanism 30, is driven by the motor 39, and the movement of the motor 39 is transmitted to the front wheels so that the steering angle changes.

As the motor 39, for example, a brush DC motor driven by pulse width modulation according to a target drive current is used. When the movement of the motor 39 is transmitted to the front wheels so that the steering angle changes, the motor 39 is closed-loop controlled according to the variable representing the running state of the vehicle.
Depending on the variable, the input shaft 2 to the output shaft 11
It is possible to change the rotation transmission ratio to the steering wheel, that is, the ratio between the operation amount of the steering wheel H and the steered amount of the front wheels.
In the present embodiment, the variable representing the traveling state is the vehicle speed. For example, in the stationary state where the vehicle speed is zero, the rotation transmission ratio from the input shaft 2 to the output shaft 11 is set to 1 by controlling the motor 39 so that the rotation angular velocity of the input shaft 2 becomes equal to the rotation angular velocity of the ring gear 32. To do. Further, the rotational angular velocity of the ring gear 32 is decreased as the speed becomes higher, and the planetary gear mechanism 30 functions as a reduction gear mechanism, whereby the turning performance of the vehicle at low speed and the traveling stability at high speed can be improved.

As shown in FIG. 2, the motor 39 is controlled by a control device 40 mounted on the vehicle. The control device 40 includes a vehicle speed sensor 41 as a sensor for detecting a variable representing a running state, and a steering angle sensor 42 for detecting a rotation angle of the input shaft 2 as an operation amount of the steering wheel H.
And a rotation angle sensor 43 that detects the rotation angle of the output shaft 11 as the turning amount of the front wheels. The control device 40 controls the motor 39 in a closed loop so as to reduce the deviation between the detected turning angle of the input shaft 2 and the detected turning angle of the output shaft 11 obtained from the vehicle speed.

FIG. 3 is a control block diagram of the control system in the steering system 1. 3, Ti is the steering torque of the steering wheel H, V is the value detected by the vehicle speed sensor 41, θi is the value detected by the steering angle sensor 42 of the rotation angle of the input shaft 2, and θo is the rotation angle of the output shaft 11. The value detected by the angle sensor 43, θo ^* is the target rotation angle of the output shaft 11, i ^* is the target drive current that is the target control amount of the motor 39, C1 is the target rotation angle θo of the output shaft with respect to the rotation angle θi of the input shaft 2. ^* Control part, C2
Is an adjusting unit of the target drive current i ^* of the motor 39 with respect to the deviation (θo ^* −θo) between the target rotation angle θo ^* and the rotation angle θo of the output shaft 11. The control device 40 calculates the target rotation angle θo ^* of the output shaft 11 with respect to the rotation angle θi of the input shaft 2 detected by the steering angle sensor 42 based on a predetermined and stored relationship. In this embodiment, the adjusting portion C1 of the target rotation angle θo ^* of the output shaft with respect to the rotation angle θi of the input shaft 2 is a proportional control element, and the target rotation angle of the output shaft 11 is θo ^* = K.
(V) · θi Here, K (V) is a proportional gain and is a function of the vehicle speed V. The proportional gain K (V) representing the relationship between the rotation angle θi of the input shaft 2, the vehicle speed V, and the target rotation angle θo ^* of the output shaft 11 is stored in the control device 40. For example, as shown in FIG. 4, the proportional gain K (V) decreases as the vehicle speed V increases, and this relationship is stored in the control device 40. The control device 40 calculates the target rotation angle θo ^* of the output shaft 11 based on the stored proportional gain K (V), the detected rotation angle θi of the input shaft 2 and the detected vehicle speed V. The control device 40 stores the relationship between the deviation (θo ^* −θo) between the target rotation angle θo ^* of the output shaft 11 and the detected rotation angle θo, and the target drive current i ^* of the motor 39. In the present embodiment, the adjustment unit C2 of the target drive current i ^{* with} respect to the deviation (θo ^* −θo) is a proportional-integral (PI) control element,
The target drive current i ^* is calculated by i ^* = G · (θo ^* −θo). Here, G is a transfer function, for example, Kg is a gain, T is a time constant, and the transfer function G is set to G = Kg · [1 + 1 / (T · s)] so that PI control is performed, and its gain Kg and time constant T are set so that optimum control can be performed. The transfer function G is stored in the control device 40.

The control device 40 has a steering wheel H.
Is calculated as a time change d (θi) / dt of the detected rotation angle θi of the input shaft 2, and a set value α of the vehicle speed that serves as a criterion for determining whether the vehicle is in the condition for suppressing the swing-back. Steering wheel H operating speed setting value β
And remember. The vehicle speed is set to the set value α and β.
As described above, if the operation speed of the steering wheel H is equal to or higher than the set value β, it may be determined in advance by experiment so that the condition for suppressing the swing back is required. In the present embodiment, the steering wheel H increases as the set value α of the vehicle speed increases.
The set value β of the operating speed of is reduced, and for example, the relationship between the set value α of the vehicle speed and the set value β of the operating speed of the steering wheel H indicated by the curve 99 in FIG. 5 is stored in the control device 40. When the steering wheel H is operated so as to decrease the steering angle, the detected vehicle speed V is equal to or greater than the stored set value α and the operating speed d (θi) / dt of the steering wheel H is equal to or greater than the stored set value β. If so, it is determined that the rocking-back suppression is required, and if not, it is determined that the rocking-back suppression is required. The set value α of the vehicle speed and the set value β of the operation speed of the steering wheel H may be constant values.

The control device 40 stores the set upper limit value η of the steered speed of the front wheels for suppressing the swing back. The set upper limit value η may be determined in advance by experiment so that the swing-back can be suppressed if the turning speed of the front wheels is equal to or lower than the set upper limit value η. The set upper limit value η may be a constant value, or the vehicle speed V or the operation speed d (θi) / d of the steering wheel H.
It may be changed according to the change of t. When the control device 40 determines that the vehicle is in the swing-back suppression necessary state, when the steering wheel H is operated so as to decrease the steering angle, the steering speed of the front wheels is limited to the stored upper limit value η or less. The motor 39 is controlled so that

The control device 40 determines whether or not the vehicle is in the danger avoidance steering state. In the present embodiment, the vehicle is in the braking state, and the operation speed d (θ of the steering wheel H is
When i) / dt is equal to or larger than the second set value ζ which is larger than the set value β that is the reference for determining whether or not the swing-back suppression is required, it is determined that the danger avoidance steering state is set. for that reason,
The control device 40 determines whether or not the vehicle is in the braking operation based on whether or not the lighting signal of the brake lamp is input, and also stores the second set value ζ. The second set value ζ is the braking state of the vehicle, and the steering wheel H
When the operating speed d (θi) / dt of is equal to or greater than the second set value ζ, it may be determined in advance by experiments so that the vehicle is in the danger avoidance steering state. When the control device 40 determines that the vehicle is in the danger avoidance steering state, the control of the motor 39 for limiting the turning speed of the front wheels to be equal to or lower than the set upper limit value η is performed even in the swing-back suppression necessary state. To release.

A control procedure by the control device 40 will be described with reference to the flowchart of FIG. First, the detection value of each sensor is read (step 1). Next, the proportional gain K (V) corresponding to the detected vehicle speed V is obtained (step 2), and the target rotation angle θo of the output shaft 11 is calculated from the obtained proportional gain K (V) and the detected rotation angle θi of the input shaft 2. ^* Is calculated (step 3), and the deviation (θo ^* -θo) between the target rotation angle θo ^* and the detected rotation angle θi of the output shaft 11 is calculated.
And the target drive current i ^* from the transfer function G (step 4). Next, the detected rotation angle θ of the output shaft 11
It is determined whether or not the steering wheel H is being operated so as to decrease the steering angle depending on whether or not o is decreasing (step 5). When the steering wheel H is operated to decrease the steering angle in step 5 (step 5
YES), the operating speed of the steering wheel H d (θ
i) / dt is obtained (step 6), and the detected vehicle speed V is equal to or higher than the set value α and the operation speed d (θi) / dt of the steering wheel H is equal to or higher than the set value β. It is determined whether or not (step 7). If it is determined in step 7 that the swing-back suppression is required, the lighting signal of the brake lamp is input, and the operation speed d (θi) / dt of the steering wheel H is set to the second value.
It is determined whether or not the danger avoidance steering state is equal to or larger than the set value ζ (step 8). When the steering wheel H is not operated to decrease the steering angle in step 5 (NO in step 5), when it is determined in step 7 that the swing-back suppression is not required (N in step 7)
O), when it is determined in step 8 that the vehicle is in the danger avoidance steering state (YES in step 8), the control of the motor 39 for limiting the turning speed of the front wheels to the set upper limit value η or less is released (step 9), Target drive current i ^* obtained in step 4
The motor 39 is driven based on the above (step 10). Next, whether to end the control is determined by, for example, whether or not the ignition switch of the vehicle is on (step 1
1) If not completed (NO in step 11), return to step 1. When it is determined in step 8 that the vehicle is not in the danger avoidance steering state (NO in step 8), step 4
The steered speed s of the front wheels when the motor 39 is driven is calculated based on the target drive current i ^* obtained in (step 12),
It is determined whether or not the calculated front wheel turning speed s exceeds the set upper limit value η (step 13). If the front wheel turning speed s is less than or equal to the set upper limit value η in step 13 (NO in step 13), the target drive current i ^* in step 10
The motor 39 is driven based on When the front wheel turning speed s exceeds the set upper limit value η in step 13 (YES in step 13), the motor 39 is controlled so that the front wheel turning speed becomes the set upper limit value η (step 14), and step 1
At 1, it is determined whether or not the control is ended.

According to the above-described embodiment, since the turning speed of the front wheels is slowed when the condition for suppressing the swing-back is slowed down, the turning speed of the front wheels is slowed down when the turning angle of the front wheels is reduced. As a result, the difference between the cornering force of the front wheels and the cornering force of the rear wheels when the steering angle is reduced becomes small, so that it is possible to prevent the cornering force of the rear wheels from becoming significantly larger than the cornering force of the front wheels. Therefore, it is possible to prevent the yaw rate of the vehicle acting in the direction opposite to the steering direction of the front wheels from increasing, and suppress the swing back. For example, as indicated by a broken line in (1) of FIG. 10, the turning speed when the turning angle θ of the front wheels increases in one direction with the passage of time t and then decreases to return straight ahead is shown by a solid line. It is slower than the conventional example shown by. As a result, the decreasing speed of the cornering force Ff of the front wheels shown by the broken line in (2) of FIG. 10 is also slower than that of the conventional example shown by the solid line. At this time, the decreasing speed of the cornering force Fr of the rear wheels is also slower than the conventional example shown by the solid line as shown by the broken line in (3) of FIG. 10, but the cornering force of the front wheels and the cornering force of the rear wheels are The difference between is small. Therefore, (4) in FIG.
As indicated by the broken line, the yaw rate γ of the vehicle that acts in the direction opposite to the steered direction of the front wheels when returning straight ahead is reduced as compared to the conventional case, and swingback is suppressed. At this time, the control is simple because the turning speed of the front wheels only needs to be reduced, and the tire load does not increase because the cornering force of the front wheels does not increase more than necessary. Further, in the danger avoidance steering state, the steered speed of the front wheels does not slow down, so that it is possible to prevent the steering angle change of the vehicle from being delayed.

FIG. 7 shows a vehicle steering system employing a so-called steer-by-wire system according to a second embodiment of the present invention. This vehicle steering system includes an operating member 101 imitating a steering wheel, a steering motor (electric actuator) 102 driven by a rotating operation of the operating member 101, and a movement of the steering motor 102 by operating the operating member. A steering gear 103 is provided which transmits the left and right front wheels 104 for steering so that the steering angle changes according to the movement of the front wheel 101 without mechanically connecting the front wheel 104. The steering motor 102 can be configured by an electric motor such as a known brushless motor. The steering gear 103 has a motion conversion mechanism that converts the rotational motion of the output shaft of the steering motor 102 into the linear motion of the steering rod 107. The movement of the steering rod 107 is transmitted to the front wheel 104 via the tie rod 108 and the knuckle arm 109, and the front wheel 10
The toe angle of 4 changes. A known gear can be used as the steering gear 103, and the configuration is not limited as long as the movement of the steering motor 102 can be transmitted to the front wheels 104 so that the steering angle changes. Note that the wheel alignment is set so that the front wheels 104 can be returned to the straight-ahead steering position by the self-aligning torque when the steering motor 102 is not driven. The operation member 10
1 is connected to a rotary shaft 110 that is rotatably supported by the vehicle body side. The elastic member 13 which gives the elastic force in the direction of returning the operating member 101 to the straight steering position.
0 is provided.

An angle sensor 111 for detecting the rotation angle of the rotary shaft 110 as a sensor for detecting the operation amount of the operating member 101, a steering angle sensor 113 for detecting the steering angle as a sensor for detecting the turning amount, and a running state A speed sensor 114 for detecting the vehicle speed and a yaw rate sensor 116 for detecting the yaw rate of the vehicle are provided as sensors for detecting the variable. The angle sensor 111, the steering angle sensor 113,
The speed sensor 114 and the yaw rate sensor 116 are connected to the control device 120 including a computer.

The control device 120 includes a steering motor 10
When transmitting the movement of 2 to the front wheels 104 such that the steering angle changes, by performing the closed loop control of the steering motor 102 via the drive circuit 122 according to the vehicle speed and the yaw rate,
The ratio between the operation amount of the operation member 101 and the steered amount of the front wheels 104 is changed according to the vehicle speed and the yaw rate.

FIG. 8 is a block diagram showing the configuration of the control system of the control device 120 of the second embodiment. Here, γ is the detected value of the yaw rate of the vehicle 100, γ ^* is the target value of the yaw rate, V is the detected value of the vehicle speed, δh is the detected value of the rotation angle of the operating member 101, δ is the detected value of the steering angle, and δ ^*. Is the target steering angle, i
^* Is the target value of the drive current of the steering motor 102, and G1 is δ
γ ^* is a transfer function of the adjusting part with respect to h, G2 is a transfer function of the adjusting part of δ ^* with respect to the deviation between γ ^* and γ, and G3 is a transfer function of the adjusting part of i ^* with respect to the deviation between δ ^* and δ. . The steering motor 102 is configured to reduce the deviation between the detected δ and the δ ^* obtained from the detected δh, V, and γ.
Closed loop control. That is, γ ^* for that δh
The adjusting unit is, for example, a proportional control element, the proportional gain is proportional to the vehicle speed V, and the following relationship is stored in the control device 120 with the proportional constant being K. γ ^* = G1 · δh = K · V · δh The adjustment unit of δ ^* with respect to the deviation between γ ^* and γ is, for example, P
The following relationship is stored in the control device 120, where I is an I control element, Ka is a gain, and Ta is a time constant. δ ^* = G2 · (γ ^* −γ) = Ka [1 + 1 / (Ta ·
s)] (γ ^* −γ) The adjustment unit of i ^* with respect to the deviation between δ ^* and δ is, for example, P
The following relationship is stored in the control device 120, where I is an I control element, Kb is a gain, and Tb is a time constant. i ^* = G3 · (δ ^* −δ) = Kb [1 + 1 / (Tb ·
s)] (δ ^* -δ) The proportional constant K, the gains Ka and Kb, the time constants Ta and Tb
Is adjusted appropriately for optimum control.

The control device 120 calculates the time change d (δh) / dt of the detected rotation angle δh of the rotary shaft 110 as the operation speed of the operation member 101, and suppresses the vehicle from rolling back as in the first embodiment. The vehicle speed set value α and the operation speed set value β of the operating member 101, which serve as a criterion for determining whether or not the vehicle is in the necessary state, are stored. When the control device 120 operates the operation member 101 so as to decrease the steering angle, the detected vehicle speed V is equal to or higher than the set value α and the operation speed d (δh) / dt of the operation member 101 is equal to or larger than the set value β. If so, it is determined that the rocking-back suppression is required, and if not, it is determined that the rocking-back suppression is required.

As in the first embodiment, the control device 120 stores the set upper limit value η of the turning speed of the front wheels 104 for suppressing the swing-back. When the control device 120 determines that the vehicle 100 is in the swing-back suppression required state, the operation member 10
When 1 is operated to decrease the steering angle, the steering motor 102 is controlled so that the turning speed of the front wheels 104 is limited to the set upper limit value η or less.

The control device 120 determines whether or not the vehicle 100 is in the danger avoidance steering state. Therefore, also in the present embodiment, as in the first embodiment, the control device 120 determines whether or not the vehicle 100 is in the braking operation depending on whether or not the lighting signal of the brake lamp is input. In addition, the control device 120 controls the operation speed d (δ of the operation member 101 as in the first embodiment.
A second set value ζ that is larger than the set value β that serves as a criterion for determining whether or not h) / dt is the swing-back suppression required state is stored. The control device 120 indicates that the vehicle 100 is in a braking state,
In addition, the operating speed of the steering wheel H d (δh) /
When dt is equal to or greater than the second set value ζ, it is determined that the danger avoiding steering state is set. When the control device 120 determines that the vehicle 100 is in the danger avoidance steering state, the control of the steering motor 102 for limiting the turning speed of the front wheels 104 to be equal to or less than the set upper limit value η is in the swing-back suppression necessary state. Even cancel it.

The above control will be described with reference to the flow chart of FIG.
The control procedure by the device 120 will be described. First, each sensor
The detected value of is read (step 101). Then detect
Target yaw rate γ corresponding to the rotation angle δh and the vehicle speed V^* To
Calculate from the stored relationship (step 102) and set the target
Yaw rate γ^* Corresponding to the deviation from the detected yaw rate γ
Target steering angle δ^* From the stored relationship (step
103), the target steering angle δ^* Deviation from the detected steering angle δ
Target drive current i of the steering motor 102 corresponding to ^* Note
The calculation is performed from the stored relationship (step 104). Next, rudder
The steering angle of the operation member 101 is reduced from the detection value of the angle sensor 113.
It is judged whether or not the amount is reduced (step 10).
5). In step 105, the steering angle of the operating member 101
When operating to decrease (YE at step 105)
S), obtain the operation speed d (δh) / dt of the operation member 101
(Step 106), the detected vehicle speed V is stored in the set value α
The above is the operation speed d (δh) of the operation member 101.
/ Dt is greater than or equal to the stored set value β.
It is determined whether or not it is in the state (step 107). Ste
At 107, it is determined that the swing-back suppression is required.
If yes (YES in step 107), brake lamp
Lighting signal is input and the operating speed of the operating member 101
Avoiding danger where the degree d (δh) / dt is greater than or equal to the second set value ζ
It is determined whether or not it is in the steering state (step 108).
In step 105, the steering angle of the operation member 101 is reduced.
When not operating like (NO at step 105),
In step 107, it is not in a state in which swing back suppression is required.
If it is determined (NO in step 107), step 1
When it is determined that the vehicle is in the danger avoidance steering state in 08
(YES in step 108), the steering speed of the front wheels 104
Control of the steering motor 102 to limit it to the set upper limit value η or less
Was canceled (step 109), and it was calculated in step 104.
Target drive current i^* Drive the steering motor 102 based on
(Step 110). Then whether to end the control
The ignition switch of vehicle 100 is turned on.
If it does not end, it is judged whether or not (step 111).
If so, the process returns to step 101. In step 108
When it is determined that the vehicle is not in the steep avoidance steering state (step 10
No in step 8), the target drive current i obtained in step 104^* 
Front wheel 10 when the steering motor 102 is driven based on
The steering speed s of 4 is calculated (step 112), and the calculation is performed.
Whether the front wheel turning speed s exceeds the set upper limit value η
Cut off (step 113). Previous in step 113
If the wheel turning speed s is less than or equal to the set upper limit value η (step 1
No in step 13) In step 110, target drive current i ^* 
The steering motor 102 is driven based on the above. Step 11
3, the front wheel turning speed s exceeds the set upper limit value η
(YES in step 113), the front wheel turning speed is set upper limit
The steering motor 102 is controlled so that the value becomes η (step
114), whether control is ended in step 111
Determine whether or not.

According to the second embodiment, the operating member 10
In the vehicle in which the first wheel 104 and the front wheel 104 are not mechanically connected, the same operational effect as in the first embodiment can be obtained.

The present invention is not limited to the above embodiment. For example, it may be determined that the vehicle is in the danger avoidance steering state when the vehicle is in the braking state or when the operating speed of the operating member is equal to or higher than the second set value. Further, in the first embodiment, the operation amount of the steering wheel H is used as a variable representing the traveling state of the vehicle, and the operation amount of the steering wheel H detected by the steering angle sensor 42 is used in place of or together with the vehicle speed of the motor 39. You may make it control according to. When the operation amount is large, the turning performance of the vehicle can be improved by increasing the rotation transmission ratio from the input shaft 2 to the output shaft 11 as compared with the case where the operation amount is small. Further, the planetary gear mechanism 3 which is connected to the output shaft 11 by connecting the ring gear 32 or the carrier 34 of the planetary gear mechanism 30 to the input shaft 2 in the first embodiment.
0 is the sun gear 31 or the ring gear 32 not connected to the input shaft 2, and the component of the planetary gear mechanism 30 driven by the motor 39 is the sun gear 31 or the carrier 34 not connected to the input / output shafts 2 and 11. May be That is, the sun gear 31,
Any one of the planetary gear elements of the ring gear 32 and the carrier 34 is connected to the input shaft 2, and any one of the planetary gear elements that is not connected to the input shaft 2 is connected to the output shaft 11, and each planetary gear element is connected. A gear element which is not connected to the input / output shaft may be rotationally driven by the motor 39. Further, a rotation transmission mechanism other than the planetary gear mechanism 30, for example, a planetary cone type rotation transmission mechanism may be used. In addition, in each of the embodiments, when the electric actuator is controlled according to the variable representing the traveling state of the vehicle, if the ratio of the operation amount of the operation member and the steered amount of the front wheels can be changed according to the variable. Therefore, the configuration of the control system is not particularly limited.

[0031]

According to the present invention, it is possible to prevent the rolling back of the vehicle when the steering angle of the vehicle is reduced without requiring complicated control and without increasing the load on the tires, and to influence the danger avoiding steering. It is possible to provide a steering device for a vehicle that does not have a vehicle.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a steering device according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram of a control configuration of the steering system according to the first embodiment of the present invention.

FIG. 3 is a block diagram of a control system in the steering system according to the first embodiment of the present invention.

FIG. 4 is a diagram showing an example of a relationship between a proportional gain K (V) and a vehicle speed V in the control system of the steering system according to the first embodiment of the present invention.

FIG. 5 is a diagram showing a relationship between a set value of a vehicle speed and a set value of an operating speed of a steering wheel H in the steering system according to the embodiment of the present invention.

FIG. 6 is a flowchart showing a control procedure in the steering system according to the first embodiment of the present invention.

FIG. 7 is a structural explanatory view of a steering device according to a second embodiment of the present invention.

FIG. 8 is a block diagram of a control system in the steering system according to the second embodiment of the present invention.

FIG. 9 is a flowchart showing a control procedure in the steering system according to the second embodiment of the present invention.

10A is a diagram showing a relationship between a turning angle θ of a front wheel and a time t; FIG. 10B is a diagram showing a relationship between a cornering force Ff of a front wheel and a time t; FIG. The figure which shows the relationship between cornering force Fr and time t, (4) is a figure which shows the relationship between the yaw rate γ of a vehicle and time t.

[Explanation of symbols]

2 input shaft 11 Output shaft 30 Planetary gear mechanism 39 motor 40 control device 41 vehicle speed sensor 42 Rudder angle sensor 43 Rotation angle sensor 101 Operation member 102 Steering motor 103 steering gear 104 front wheel 111 angle sensor 113 rudder angle sensor 114 speed sensor 116 Yaw rate sensor 120 control device H steering wheel

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) B62D 137: 00 B62D 137: 00 (72) Inventor Nishizaki Masaru 3-5-8 Minamisenba, Chuo-ku, Osaka-shi, Osaka No. Koyo Seiko Co., Ltd. (72) Inventor Tomoho Kada 3-5-8 Minamisenba, Chuo-ku, Osaka-shi, Osaka Inside Koyo Seiko Co., Ltd. (72) Masaya Segawa 3-5, Minamisenba, Chuo-ku, Osaka-shi, Osaka No. 8 F-term in Koyo Seiko Co., Ltd. (reference) 3D032 CC50 DA03 DA15 DA23 DA33 DA63 DA91 DA93 DB02 DB03 DC01 DC02 DC03 DC09 DC33 DC34 DC35 DD02 DD06 DD07 DE05 DE09 EA01 EB04 EB11 EB12 EB16 EB22 EC23 GG01 3D033 CA13 CA16 CA17 CA17 CA17 CA17

Claims (6)

[Claims] 1. When transmitting a movement of an electric actuator to a front wheel so that a steering angle changes, the electric actuator is controlled according to a variable representing a running state of a vehicle,
In a vehicle steering system capable of changing the ratio of the operation amount of the operation member and the turning amount of the front wheels according to the variable,
When operating the operating member to decrease the steering angle, if the vehicle speed is equal to or higher than the set value and the operating speed of the operating member is equal to or higher than the set value, the steering speed of the front wheels is oscillating. A steering apparatus for a vehicle, wherein the electric actuator is controlled so as to be limited to an upper limit value or less set for restraining return. 2. An operating member, means for detecting an operation amount of the operating member, an electric actuator, a control device for the electric actuator, and movement of the electric actuator can be transmitted to a front wheel so that a steering angle changes. And a sensor that detects at least the vehicle speed as a variable representing the running state of the vehicle, and the electric actuator is configured so that the ratio between the operation amount of the operating member and the steering amount of the front wheels changes according to the detected variable. In a controlled vehicle steering system, a means for obtaining an operation speed of an operation member, a set value of a vehicle speed and a set value of an operation speed of an operation member, which serve as a reference for determining whether or not the vehicle is in a condition for suppressing swinging back. When the operating member and the operating member are operated so as to decrease the steering angle, the vehicle speed is equal to or greater than the stored set value and the operating speed of the operating member is equal to or greater than the stored set value. Then, a means for determining whether or not the vehicle is in the suppression-requiring state, and a means for storing the set upper limit value of the turning speed of the front wheels for suppressing the swinging-back are provided, and when the vehicle is in the shaking-back suppressing required state, A steering apparatus for a vehicle, wherein the electric actuator is controlled such that a steered speed of the front wheels is limited to a stored upper limit value or less when operating the operating member so as to decrease the steering angle. 3. A means for determining whether or not the vehicle is in a danger avoidance steering state, and when the vehicle is in the danger avoidance steering state, the electric actuator of the electric actuator for limiting the turning speed of the front wheels to a set upper limit value or less. The vehicle steering system according to claim 1, wherein the control is released. 4. When the vehicle is in a braking state and the operating speed of the operating member is equal to or greater than a second set value which is a reference value for determining whether or not the swing-back suppression is required. The vehicle steering apparatus according to claim 3, wherein the vehicle is in a danger avoidance steering state. 5. An input shaft that rotates in response to an operation of the operating member, an output shaft, a rotation transmission mechanism that transmits the rotation of the input shaft to the output shaft, and a rotation angle of the output shaft to the front wheels. A steering gear that transmits in a varying manner, and by driving the constituent elements of the rotation transmitting mechanism by the electric actuator, the movement of the electric actuator is transmitted to the front wheels such that the steering angle changes. The steering apparatus for a vehicle according to any one of 4 to 4. 6. The movement of the electric actuator is transmitted to the front wheels such that the steering angle changes according to the movement without mechanically connecting the operating member to the front wheels.
The steering apparatus for a vehicle according to any one of 4 to 4.