JPH07112822B2 - 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 of the wheel steering angle to the steering 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.

Therefore, in order to meet 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. Has proposed a speed-sensitive steering device. This is provided with a speed change mechanism including a pair of variable pitch pulleys facing each other and a V belt wound between both pulleys, between the steering handle and the steering column, and the vehicle speed is controlled by the pitch diameter of the driven pulley. It is controlled by a stepping motor so that it becomes larger as it rises. 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, when the transmission ratio of the wheel steering angle to the steering wheel steering angle of the steering handle is variably controlled according to the vehicle speed or the like as described above, a driver is not required when the vehicle is traveling straight ahead. When the steering wheel is operated to slightly change the steering angle of the steering wheel, the transmission ratio is immediately variably controlled according to this change, and the wheels are steered. Therefore, measures are required to ensure running stability.

The present invention has been made in view of the above points, and an object thereof is to perform variable control of the transmission ratio of the wheel steering angle with respect to the steering wheel steering angle when the steering wheel steering angle is within a small steering angle range. By performing the operation in the predetermined manner, it is possible to prevent the wheels from being unnecessarily steered even if the steering angle of the steering wheel slightly changes when the vehicle is traveling straight, and to improve the traveling stability.

(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. Furthermore, a steering wheel steering angle sensor that detects the steering angle of the steering wheel, and a controller that inputs an output signal from the steering wheel steering angle sensor and outputs a control signal to the transmission ratio varying means are provided, and the controller includes: When the steering angle of the steering wheel is within the minute steering angle range, a dead zone is set to output a control signal for inhibiting the steering angle change of the steered wheels to the transmission ratio varying means.

(Operation) Therefore, according to the present invention, when the steering wheel is steered to steer the wheels, the steering angle of the steering wheel is detected by the steering wheel steering angle sensor when the steering wheel is steered. The controller that receives the output signal from the sensor controls the transmission ratio varying means so that the transmission ratio of the wheel steering angle to the steering wheel steering angle is variably controlled according to the steering wheel steering angle. At this time, the dead zone is set in the controller, and due to this dead zone,
When the steering angle of the steering wheel is within a small steering angle range around zero when the vehicle is running straight, the control signal output from the controller to the transmission ratio varying means prohibits the steering wheel from changing the steering angle. From this, even if a slight wobble occurs in the steering wheel due to an unnecessary operation of the driver during straight traveling, the wheel steering angle is surely kept at zero, so that the traveling stability of the vehicle is further ensured.

(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 amount 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, ... Arranged at equal angular intervals so as to mesh with both gears 14, 15 between 5
, And the pinion carrier 16, which carries the pinions 16, 16 through the pinion shafts 17, 17, and which is rotatably fitted on the input shaft 12. A sector gear 19 is formed on the pinion carrier 18, and a pinion 21 fixed to a rotary shaft 20a of a stepping motor 20 is meshed with the sector gear 19. Then, the pinion carrier 18 is rotated around the input shaft 12 by the rotation of the stepping motor 20, and the planetary pinions 16, 16, ... Carried on the carrier 18 are rolled between the sun gear 14 and the ring gear 15, and this pinion is rotated. By changing the amount of rotation from the handle shaft 2 or the sun gear 14 to the ring gear 15 and the intermediate shaft 4 by rolling 16, 16, ..., The transmission ratio R of the wheel steering angle θ _{W to} the steering wheel steering angle θ _H is changed. Is configured to let.

On the other hand, reference numeral 33 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 33 is provided with the steering angle θ _H of the steering handle 1. A steering wheel steering angle sensor 30 composed of an encoder for detecting,
Output signals from a vehicle speed sensor 31 that detects the vehicle speed V of the vehicle are input. As shown in detail in FIG. 5, the controller 33 sets the steering wheel steering angle θ _H and the vehicle speed V respectively detected by the steering wheel steering angle sensor 30 and the vehicle speed sensor 31 in advance as shown in FIG. Characteristics storage
A target transmission ratio calculation unit 34 for calculating a target transmission ratio R to be controlled by the transmission ratio variable unit 9 by collating and comparing with a characteristic map stored in 32, and a stepping motor 20 based on an output signal of the calculation unit 34. Is driven so as to match the rotation angle corresponding to the calculated target transmission ratio R. Then, the characteristic map, the transfer ratio R of the wheel steering angle theta _W for steering angle theta _H as shown, made as steering angle theta _H beyond the dead zone Z increases, and as the vehicle speed V is slower decrease Is set.
Therefore, when the steering angle θ _H of the steering wheel when the vehicle is traveling straight ahead is within the range in which the steering wheel steering angle θ _H changes from zero to the left and right, a control signal that prohibits the steering wheels 8 and 8 from changing the steering angle is generated. Is set to the transmission ratio varying means 9 and the dead zone Z prevents the wheel steering angle θ _W from changing even if the steering wheel 1 wobbles.

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 30, and the vehicle speed V at that time is detected by the vehicle speed sensor 31, and the outputs of both sensors 30, 31 are detected. The stepping motor of the transmission ratio varying means 9 from the controller 33 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 33. 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 angle θ _{H of the} steering wheel. As a result, the wheels 8, 8 are steered, whereby the transmission ratio R of the wheel steering angle θ _{W to} the steering wheel steering angle θ _H is variably controlled.

In that case, the wheel steering angle θ _{W with} respect to the steering wheel steering angle θ _H
The transmission ratio R as steering angle theta _H as shown in FIG. 6 by the controller 33 is increased, also it is determined so as smaller the vehicle speed V is slow, as shown, steering angle theta _H Is in the dead zone Z in the range of a predetermined angle from zero to the vicinity thereof (within a small steering angle range), the control signal output from the controller 33 to the stepping motor 20 of the transmission ratio varying means 9 changes the transmission ratio R to R. The signal keeps = 0, and the change in the steering angle of the steered wheels 8 and 8 is prohibited. Therefore, even if the steering wheel 1 wobbles within the dead zone Z due to an unnecessary operation of the driver during straight running, the wheel steering angle θ _W does not change and remains at zero, and sufficient running stability is ensured. You can do it.

In the above embodiment, the transmission ratio of the wheel steering angle to the steering wheel steering angle is variably controlled according to the steering wheel steering angle and the vehicle speed, but it is also possible to variably control only the steering wheel steering angle. it can.

(Advantages of the Invention) As described above, according to the present invention, in the steering apparatus of an automobile in which the transmission ratio of the wheel steering angle to the steering wheel steering angle is changed by the transmission ratio varying means, the steering angle of the steering wheel is small. When the vehicle is in the range, the transmission ratio is variably controlled so as to prohibit the steering wheel from changing its steering angle. Even if a slight change occurs, the influence is not exerted on the wheels, so that the running stability can be sufficiently ensured.

[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 a controller, and FIG. 6 is a characteristic diagram of a map read by a calculation unit of the controller. 1 ... Steering handle, 3 ... Steering gear device, 8 ... Wheels, 9 ... Transmission ratio varying means, 13 ... Planetary gear mechanism, 20 ... Stepping motor, 30 ... Steering wheel angle sensor, 33 ... Controller, Z ... dead zone.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Hitoshi Nakajima 3-1, Shinchi, Fuchu-cho, Aki-gun, Hiroshima 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 steered wheel via a steering gear device and changing a transmission ratio of a wheel steering angle to a steering wheel steering angle, The steering wheel steering angle sensor for detecting a steering angle of the steering wheel, and a controller for inputting an output signal from the steering wheel steering angle sensor and outputting a control signal to the transmission ratio varying means, the controller includes: When the steering angle of the steering wheel is within the range from zero to a small steering angle, there is provided a dead zone for outputting a control signal for prohibiting the change of the steering angle of the steered wheels to the transmission ratio varying means. .