JPH0674053B2 - Car steering device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steering device capable of changing a transmission ratio (reduction ratio) of a wheel steering angle to a steering wheel steering angle of an automobile.

(Prior Art) Generally, a steering device of an automobile converts a rotational motion of a steering handle into a lateral displacement motion of a tie rod through a steering gear device such as a rack and pinion, and is connected to both ends of the tie rod. Although the direction of the left and right steered wheels is changed, the rotation amount of the steering wheel (steering wheel steering angle) and the steering angle of the wheel (wheel steering angle) are normally held in a fixed correspondence relationship. However, for example, when a vehicle is traveling at high speed, it is desirable to secure traveling stability by increasing the transmission ratio from the steering wheel steering angle to the wheel steering angle to reduce the size of the wheel steering angle with respect to a constant steering wheel steering angle. On the other hand, when driving at low speed, from the viewpoint of speeding up the behavior of the vehicle to obtain a good driving feeling, or facilitating garage parking, the above transmission ratio is reduced to the contrary to the wheel for a certain steering wheel steering angle. It is desirable to increase the steering angle.

Then, in order to satisfy such a demand, conventionally, for example, as disclosed in JP-A-58-224852, the transmission ratio of the wheel steering angle to the steering wheel steering angle is changed according to the vehicle speed of the automobile. A vehicle speed sensitive steering device has been proposed. This is provided with a belt type continuously variable transmission mechanism including a pair of variable pitch pulleys facing each other and a V belt wound between the pulleys, between the steering handle and the steering column, and the pitch of the driven pulleys. The diameter is controlled by a stepping motor so that the diameter increases as the vehicle speed increases. According to this, the rotation transmission ratio from the steering wheel to the steering column increases as the vehicle speed increases, and as a result, the steering angle of the wheel with respect to a fixed steering angle decreases at high speeds and increases at low speeds. Good steering characteristics can be obtained.

(Problems to be Solved by the Invention) By the way, in the case where the transmission ratio of the wheel steering angle to the steering wheel steering angle is variably controlled according to the vehicle speed, for example, even when the vehicle travels in a curve at a constant steering wheel steering angle, When the traveling vehicle speed changes, the wheel steering angle changes due to the change in the transmission ratio, and it is preferable to gently change the transmission ratio in order to improve the steering stability.

Therefore, the responsiveness of the transmission change to the vehicle speed change described above may be set low, but when the steering angle of the steering wheel is small such as the beginning of the curve or the end of the curve when the vehicle is traveling in a curve, the wheel steering followability of the steering wheel is improved. There is an unavoidable adverse effect.

The present invention has been made in view of the above points, and an object thereof is to variably control the above-mentioned transmission ratio according to the vehicle speed and the steering angle of the steering wheel and the responsiveness of the transmission ratio change to the vehicle speed change and the steering wheel. By establishing a relationship with the steering angle, the steepness of the transmission ratio accompanying a change in vehicle speed at a large steering angle can be achieved without impairing the followability of the wheel steering for steering the steering wheel at a small steering angle. It is to be able to suppress the change.

(Means for Solving the Problem) In order to achieve the above object, the solution means of the present invention is to provide a steering wheel steering angle in a steering amount transmission path for transmitting a steering amount of a steering handle to a wheel via a steering gear device. A transmission ratio varying means for changing the transmission ratio of the wheel steering angle to the vehicle is provided. The transmission ratio varying means is composed of, for example, a planetary gear mechanism, a differential gear mechanism, and an actuator such as a stepping motor that controls the operation of the gear mechanism.

Further, a controller for controlling the operation of the transmission ratio varying means corresponding to the vehicle speed of the automobile and a steering angle detecting means for detecting the steering angle of the steering wheel are provided, and the controller controls the vehicle speed based on the signal from the steering angle detecting means. The response of the change of the transmission ratio to the change is changed according to the steering angle of the steering wheel so that the rate of change of the transmission ratio with respect to the change of the vehicle speed becomes smaller as the steering angle of the steering wheel increases.

(Operation) Therefore, according to the present invention, with the above configuration, when the steering wheel is steered to steer the wheels, the controller controls the operation of the transmission ratio variable means in accordance with the vehicle speed to change the wheel steering angle with respect to the steering wheel steering angle. The transmission ratio is variably controlled.

In that case, in the controller, the responsiveness of the transmission ratio change to the vehicle speed change changes according to the change of the steering wheel steering angle detected by the steering angle detecting means, and the transmission ratio of the transmission ratio to the vehicle speed change changes as the steering wheel steering angle increases. Since the change rate is configured to be small, the change rate of the transmission ratio change with respect to the vehicle speed change is increased and the responsiveness is kept high when the steering angle of the steering wheel is small. Good followability of wheel steering can be secured. On the other hand, when the steering angle is large, the rate of change of the transmission ratio change with respect to the change of vehicle speed becomes small, and the responsiveness is kept relatively low.
It is possible to suppress the sudden change of the transmission ratio with the change of the vehicle speed and improve the steering stability.

(Example) Hereinafter, the Example of this invention is described based on drawing.

FIG. 1 shows the overall construction of an embodiment of the present invention, in which 1 is a steering wheel with one end of a handle shaft 2 fixed to the center, and 3 is connected to the other end of the handle shaft 2 via an intermediate shaft 4. In addition, the left and right steering wheels 8 and 8 are connected via a link mechanism 7 including a pitman arm 5 and a tie rod 6.
Is a steering gear device connected to. A transmission ratio varying means 9 for changing the transmission ratio R of the wheel steering angle θ _{W to} the steering wheel steering angle θ _H is provided in the middle of the steering force transmission path between the steering wheel 1 and the steering gear device 3.

The transmission ratio varying means 9 is arranged on the same axis as the intermediate shaft 4 so as to face each other, and the handle shaft 2 is provided at the end opposite to the intermediate shaft 4, as shown in enlarged detail in FIGS. 2 to 4. On the other hand, it is provided with an input shaft 12 which is drivingly connected through input gears 10 and 11 which mesh with each other, and a planetary gear mechanism 13 which is arranged between the input shaft 12 and the intermediate shaft 4. The planetary gear mechanism 13 includes a sun gear 14 fixed to the input shaft 12, a ring gear 15 fixed to the intermediate shaft 4, and both gears 14, 1.
For example, three planetary pinions 16,16, etc., which are arranged at equal angular intervals so as to mesh with both gears 14,15 between 5,
, And the pinions 16, 16, ... Are attached to the pinion carrier 18 rotatably externally fitted on the input shaft 12 by the pinion shaft 1
It is carried through 7,17, .... A sector gear 19 is formed on the pinion carrier 18, and the sector gear 19 is formed.
A pinion 21 fixed to the rotation output shaft 20a of the stepping motor 20 is meshed with the stepping motor 19. Then, by rotating the stepping motor 20, the pinion carrier 18 is input to the input shaft.
12 are rotated to move the planetary pinions 16, 16, ... Supported on the carrier 18 while rolling between the sun gear 14 and the ring gear 15, and the handle shaft 2 is moved by the movement of the pinions 16, 16 ,. Or Sun gear 14 to ring gear
The transmission ratio R of the wheel steering angle θ _{W to} the steering wheel steering angle θ _{H is} controlled by increasing / decreasing the rotation amount reaching 15 and the intermediate shaft 4.
Is configured to vary.

On the other hand, reference numeral 30 is a controller composed of a computer for outputting a control signal to the transmission ratio varying means 9 to control the operation of the stepping motor 20, and the controller 30 detects the steering angle θ _H of the steering wheel 1. Output signals of a steering wheel steering angle sensor 31 as a steering angle detecting means and a vehicle speed sensor 32 detecting a traveling speed V (vehicle speed) of the vehicle are input. The controller 30 is
As shown in detail in FIG. 5, the steering wheel steering angle θ _H and the vehicle speed V respectively detected by the steering wheel steering angle sensor 31 and the vehicle speed sensor 32 are converted into a transmission ratio R of the wheel steering angle θ _{W to} the steering wheel steering angle θ _H. Is compared with, for example, a characteristic map preset so as to be large at a high vehicle speed and small at a low vehicle speed to obtain a target transmission ratio R to be controlled by the transmission ratio varying means 9 and correspond to the target transmission ratio R. Stepping motor 20 target control amount (rotation angle) θ _M = f (θ _H , V)
And a stepping motor 20 based on the output signal of the calculation unit 34.
The motor drive unit 35 is driven by a pulse signal so that the actual rotation angle of the stepping motor 20 detected by 33 matches the calculated target control amount θ _M. With the configuration of the controller 30, the stepping motor 20 of the transmission ratio varying means 9 is controlled by the vehicle speed V and the steering angle θ of the steering wheel.
_The control is performed in correspondence with _H.

Further, the controller 30 is provided with a drive speed control unit 36 for controlling the drive speed _M of the stepping motor 20 according to the vehicle speed V and the steering wheel steering angle θ _H. The drive speed control unit 36 uses the actual steering wheel steering angle θ detected by the steering wheel steering angle sensor 31 and the vehicle speed sensor 32, respectively.
_The motor drive speed _M corresponding to _H and the vehicle speed V is calculated,
The motor drive unit is set so that the motor drive speed _M is achieved.
The number of pulses of the motor driving pulse signal in 35 is changed within a fixed time. Then, the drive speed calculation unit 36,
The gain when the drive speed of the motor 20 changes according to the change of the vehicle speed V is set to change according to the change of the steering angle θ _H of the steering wheel. By this setting, the response of the change of the transmission ratio to the change of the vehicle speed is set. Is changed according to the steering angle of the steering wheel, and the rate of change of the transmission ratio is reduced as the steering angle θ _{H of the} steering wheel is increased to reduce the responsiveness of the change of the transmission ratio.

Therefore, in the above embodiment, while the vehicle is running,
When the steering wheel 1 is steered, its movement is transmitted to the input shaft 12 of the transmission ratio varying means 9 via the steering shaft 2, and the sun gear 14 of the planetary gear mechanism 13 rotates. Further, the steering wheel angle θ _H that changes with the steering of the steering wheel 1 is detected by the steering wheel angle sensor 31, and the vehicle speed V at that time is detected by the vehicle speed sensor 32, and the outputs of both sensors 31, 32 are detected. The stepping motor of the transmission ratio varying means 9 from the controller 30 which receives the signal
A control signal is output to 20 to control the rotation of the motor 20,
The rotation of the motor 20 causes the pinion 21 and the sector gear 19 to rotate.
The pinion carrier 18 in the planetary gear mechanism 13 is rotationally driven via the. That is, in the transmission ratio varying means 9, the sun gear 14 rotates by an angle proportional to the steering angle θ _H of the steering wheel 1, and at the same time, the pinion carrier 18 rotates according to the rotation angle of the stepping motor 20 controlled by the controller 30. Become so. Therefore, the ring gear 15 of the transmission ratio varying means 9 and the intermediate shaft 4 integrated with the ring gear 15 rotate by an angle obtained by increasing or decreasing the rotation angle of the pinion carrier 18 with respect to the steering wheel steering angle θ _H. are wheels 8,8 steering transmission ratio R of the wheel steering angle theta _W for steering wheel angle theta _H is variably controlled in accordance with a steering angle theta _H and the vehicle speed V by this.

In that case, the drive speed controller in the controller 30
Due to the gain characteristics of 36, the transmission ratio R for changes in the vehicle speed V
Changes according to the response is a change in steering wheel angle theta _H changes, the response of the transmission ratio changes as the steering wheel angle theta _H increases is set to be lower, during cornering of the motor vehicle As shown in FIG. 6, when the steering angle θ _H is small at the beginning or the end of the bend, the response of the transmission ratio change to the vehicle speed change becomes sensitive, and the wheel steering followability to the steering is changed. On the other hand, when the steering angle θ _H is large in the middle region of the bend, the response of the change of the transmission ratio to the change of the vehicle speed becomes dull, and the rapid change of the transmission ratio R accompanying the change of the vehicle speed V can be avoided. . Therefore, it is possible to improve the steering stability when the vehicle is traveling on a curve.

(Effects of the Invention) As described above, according to the present invention, in a vehicle steering system in which the transmission ratio of the wheel steering angle to the steering wheel steering angle is changed according to the vehicle speed by the transmission ratio varying means, the transmission to the vehicle speed change is transmitted. By changing the response of the ratio change according to the steering angle of the steering wheel and decreasing the rate of change of the transmission ratio with respect to the change of the vehicle speed as the steering angle of the steering wheel increases, the response becomes low. It is possible to suppress a rapid change in the transmission ratio due to a change in the vehicle speed at a large steering angle while maintaining good followability of the wheel turning to the steering of the steering wheel, and to enhance the steering stability when the vehicle is traveling on a curve.

[Brief description of drawings]

The drawings show an embodiment of the present invention, FIG. 1 is a perspective view showing the overall construction of a steering device, FIG. 2 is a sectional view showing the construction of transmission ratio varying means, and FIG. 3 and FIG. Sectional views taken along lines III-III and IV-IV in the figure, FIG. 5 is a block diagram showing a configuration of the controller, and FIG. 6 is an explanatory view showing a state of a steering angle change when the vehicle is traveling on a curve. 1 ... Steering handle, 3 ... Steering gear device, 8 ... Wheels, 9 ... Transmission ratio varying means, 13 ... Planetary gear mechanism, 20 ... Stepping motor, 30 ... Controller, 31 ... Steering wheel steering angle Sensor, 32 ... Vehicle speed sensor,
36 …… Driving speed controller.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Maki Watanabe 3-1, Shinchi, Fuchu-cho, Aki-gun, Hiroshima Prefecture Mazda Co., Ltd. (56) Reference JP-A-59-167372 (JP, A)

Claims (1)

[Claims] 1. A transmission ratio variable means provided in a steering amount transmission path for transmitting a steering amount of a steering wheel to a wheel via a steering gear device, and changing a transmission ratio of a wheel steering angle to a steering wheel steering angle. The controller is provided with a controller for controlling the operation of the transmission ratio varying means in correspondence with the vehicle speed, and a steering angle detecting means for detecting the steering angle of the steering wheel. The controller is provided with a signal from the steering angle detecting means.
A steering apparatus for an automobile, characterized in that a change rate of a transmission ratio with respect to a change in vehicle speed is reduced as the steering angle of the steering wheel is increased.