JPS6246770A - Steering device for car - Google Patents

Abstract

PURPOSE:To improve the traveling stability in the case when a car travels on a curved road, by varying the responsiveness of the variation of transmission ratio for the variation of car speed according to the steering angle of a steering wheel, in the variation of the transmission ratio of the steering angle of wheels for the steering angle of the steering wheel. CONSTITUTION:When a steering wheel 1 is steered during the traveling of a car, the movement is transmitted to a transmission-ratio varying means 9 through the shaft 2 of the steering wheel, and a planetary gear mechanism is operated. The steering angle of the steering wheel and the car speed are detected by the sensors 31 and 32, and a controller 30 controls the revolution of a stepping motor of the transmission- ratio varying means 9 according to the above-described output signals. In this case, the responsiveness of the variation of the transmission ratio for the variation of the car speed is varied according to the variation of the steering angle, according to the gain characteristic of the driving speed control part in the controller 30, and the responsiveness in the variation of the transmission ratio is reduced as the steering angle of the steering wheel increases. Thus, the sharp variation of the transmission ratio accompanied by the car-speed variation with large steering angle can be suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a steering device that can change the transmission ratio (reduction ratio) of wheel steering angle to steering wheel steering angle of an automobile.

(Prior Art) In general, a steering device for an automobile converts the rotational movement of a steering wheel into a lateral displacement movement of a tie rod through a steering gear device such as a rack-and-binion. Although the direction of the left and right steering wheels is changed, the rotation a (handle steering angle) of the steering handle and the turning angle of the wheels (wheel steering angle) are usually always maintained in a constant correspondence relationship. . However, for example, when a car is running at high speed, it is desirable to increase 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 in order to ensure driving stability. On the other hand, when driving at low speeds, the above transmission ratio is conversely reduced in order to make the vehicle more agile and provide a good driving feeling, or to make it easier to park the car in a garage. It is desirable to increase the steering angle.

In order to meet such requirements, conventionally, as disclosed in Japanese Patent Application Laid-Open No. 58-224852,
A vehicle speed-sensitive steering device has been proposed that changes the transmission ratio of wheel steering angle to steering wheel steering angle in accordance with the vehicle speed of the vehicle. This system is equipped with a belt-type continuously variable transmission mechanism between the steering handle and the steering column, consisting of a pair of variable pitch boots facing each other and a belt wrapped between both boots. The pitch diameter is controlled by a stepping motor so that it becomes larger as the vehicle speed increases. According to this, the rotation transmission ratio from the steering wheel to the steering column increases when the vehicle speed is high;
As a result, the steering angle of the wheels relative to a constant steering angle is small at high speeds and large at low speeds, and good steering characteristics corresponding to the vehicle speed 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 is variably controlled in accordance with the vehicle speed, for example, even if the car is traveling around a curve with a constant steering wheel angle, When the traveling vehicle speed changes, the wheel steering angle changes due to the accompanying change in the transmission ratio, and it is preferable to make such a gradual change in the transmission ratio in order to improve steering stability.

Therefore, the responsiveness of the transmission ratio change to the vehicle speed change described above may be set low, but when the steering wheel angle is small, such as at the beginning or end of a curve, the responsiveness of the wheel turning to the steering wheel steering may be reduced. It is inevitable that there will be a negative impact on the

The present invention has been made in view of the above points, and an object of the present invention is to improve the responsiveness of the transmission ratio change to the vehicle speed change and the steering wheel steering angle when the transmission ratio is variably controlled according to the vehicle speed and the steering angle. By creating a relationship between the steering angle and the steering angle, sudden changes in the transmission ratio due to changes in vehicle speed at large steering angles can be avoided without impairing the ability of wheel turning to follow steering wheel steering at small steering angles. The goal is to be able to suppress change.

(Means for Solving the Problems) In order to achieve the above object, the solving means of the present invention provides a steering wheel steering wheel in a steering force transmission path that transmits the steering force of the steering wheel to the wheels via the steering gear device. A transmission ratio variable means is provided for changing the transmission ratio of the wheel steering angle to the wheel steering angle. This transmission ratio variable means includes, for example, a planetary gear mechanism, a differential gear mechanism, etc., and an actuator such as a stepping motor that controls the operation of the gear mechanism. Furthermore, a controller for controlling the operation of the transmission ratio variable means in accordance with the vehicle speed of the automobile, and a steering angle detecting means for detecting a steering wheel angle are provided, and the controller detects the vehicle speed based on the signal from the steering angle detecting means. The responsiveness of the transmission ratio change to the change is configured to be changed according to the steering angle of the steering wheel.

Therefore, in the present invention, with the above configuration, when the steering wheel is steered to turn the wheels, the controller controls the operation of the transmission ratio variable means in accordance with the vehicle speed, thereby adjusting the wheel steering angle relative to the steering wheel steering angle. The transmission ratio is variably controlled. - In that case, the above controller is configured so that the responsiveness of the transmission ratio change to a change in vehicle speed changes according to the change in the steering wheel angle detected by the steering angle detection means, so When the steering angle is small, the responsiveness of the transmission ratio change to the steering wheel angle is maintained high, ensuring good followability of the wheel turning to the steering wheel steering, while at the large steering angle, the responsiveness of the transmission ratio change to the vehicle speed change is maintained. This means that the transmission ratio can be kept relatively low, suppressing sudden changes in the transmission ratio due to changes in vehicle speed, and improving steering stability.

(Example) Embodiments of the present invention will be described below based on the drawings.

FIG. 1 shows the overall configuration of an embodiment of the present invention, where 1 is a steering handle to which one end of a handle shaft 2 is fixed, and 3 is a steering handle connected to the other end of the handle shaft 2 via an intermediate shaft 4. At the same time, Bitman Arm 5. tie rod 6
The left and right steering wheels 8, 8 are connected via a link mechanism 7 consisting of
A steering gear device connected to the steering wheel 1 and the steering gear device 3, in the middle of the steering force transmission path between the steering wheel 1 and the steering gear device 3, there is a variable transmission device that changes the transmission ratio R of the wheel steering angle θW to the steering wheel steering angle θH. Means 9 are provided.

As shown in enlarged detail in FIGS. 2 to 4, the variable transmission means 9 is disposed facing the intermediate shaft 4 on the same axis, and is attached to the handle shaft 2 at the end opposite to the intermediate shaft 4. The input shaft 12 is drive-coupled via input gears 10.11 that mesh with each other, and a planetary gear mechanism 13 is disposed between the input shaft 12 and the intermediate shaft 4. The planetary gear mechanism 13 has a ring gear (714) fixed to the input shaft 12, a ring gear 15 fixed to the intermediate shaft 4, and meshes with both gears 14 and 15 between the two gears 14 and 15, respectively. For example, 3 arranged at equal angular intervals
planetary binions 16, 16, . . .
The above binions 16, 16. . . is a binion shaft 17 . . . attached to a binion carrier 18 rotatably fitted onto the input shaft 12 .・17. It is carried through... Further, a sector gear 19 is formed in the above-mentioned binion key V 718, and a binion 21 fixed to the rotational output shaft 20a of the stepping motor 20 is meshed with the sector gear 19, and the binion carrier 18 is rotated by the rotation of the stepping motor 20. Planetary binions 16, 16 . rotated about the input shaft 12 and supported on the carrier 18 .・
... are moved while being transferred between the sun gear 14 and the ring gear 15, and the binions 16, 16 . The transmission ratio R of the wheel steering angle θW to the steering wheel steering angle θH is changed by controlling the rotation from the handle shaft 2 or sun gear 14 to the ring gear r15 and the intermediate shaft 4 by increasing or decreasing the movement of the steering wheel. ing.

On the other hand, a controller 30 is a computer that outputs a control signal to the variable transmission means 9 to control the operation of the stepping motor 20.
0 is the steering wheel angle θH of the steering wheel 1.
Steering wheel steering angle sensor 3 as a steering angle detection means for detecting
1 and a vehicle speed sensor 32 that detects the vehicle running speed 1'fV (vehicle speed). As shown in detail in FIG. 5, the controller 30 transmits the steering wheel steering angle θH and the vehicle speed ■ detected by the steering wheel steering angle sensor 31 and the vehicle speed sensor 32, respectively, and the wheel steering angle θW relative to the steering wheel steering angle θH. The target transmission ratio R to be controlled by the variable transmission means 9 is determined by comparing the ratio R with a characteristic map set in advance such that the ratio R is large at high vehicle speeds and small at low vehicle speeds, and the target transmission ratio R is The target control land of the stepping motor 20 corresponding to (
A control amount calculation unit 34 calculates rotation angle>77M=f(θ+,V), and a control amount calculation unit 34 calculates the stepping motor 20 based on the output signal of the calculation unit 34. The controller 30 has a motor drive unit 35 that is driven by a pulse signal so that the rotation angle of the rotation angle matches the target control amount θN calculated above. 20 is controlled in accordance with the vehicle speed ■ and the bundle steering angle θH.

Furthermore, the controller 30 is provided with a drive speed control section 36 that controls the drive speed 0M of the stepping motor 20 in accordance with the vehicle speed V and the steering angle θH. The drive speed control unit 36 calculates the motor drive speed 0 corresponding to the actual steering wheel angle θH and the vehicle speed V detected by the steering wheel angle sensor 31 and the vehicle speed sensor 32, respectively, and determines the motor drive speed θ. The number of pulses of the motor driving pulse signal in the motor driving section 35 within a certain period of time is changed so that

The drive speed calculation section 36 is set to change the gain when the drive speed of the motor 20 changes with a change in the vehicle speed V, in accordance with a change in the steering wheel steering angle θH. , the responsiveness of a change in the transmission ratio to a change in vehicle speed is changed in accordance with the steering angle of the steering wheel, and as the steering angle θH increases, the rate of change in the transmission ratio is decreased to lower the responsiveness of the change in the transmission ratio. ing.

Therefore, in the above embodiment, while the car is running,
When the steering wheel 1 is steered, the movement is transmitted via the steering wheel shaft 2 to the input shaft 12 of the variable means 9.
is transmitted to rotate the sun gear r14 of the planetary gear mechanism 13. Further, the steering wheel steering angle θ1 (which changes with the steering of the steering wheel 1) is detected by the steering wheel steering 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 and 32 are detected by the vehicle speed sensor 32. The controller 30 receiving the signal outputs a control signal to the stepping motor 20 of the variable transmission means 9 to control the rotation of the motor 20, and the rotation of the motor 20 causes the rotation of the planetary gear mechanism 1 via the pinion 21 and the sector gear 19.
The pinion carrier 18 at 3 is rotationally driven. That is, in the variable transmission means 9, the sun gear 14 rotates by an angle proportional to the steering angle θH of the steering wheel 1, and at the same time, the rotation carrier 18 rotates according to the rotation angle of the stepping motor 20 controlled by the controller 30. will be done. Therefore, the ring gear 15 of the variable transmission means 9 and the intermediate shaft 4 integrated therewith rotate by an angle that increases or decreases the rotation angle of the pinion carrier 18 with respect to the steering angle θH, and due to the rotation of the intermediate shaft 4. The φ wheels 8, 8 are steered, and thereby the transmission ratio R of the wheel steering angle θW to the steering wheel steering angle θH is variably controlled according to the steering angle θH and the vehicle speed V.

In that case, due to the gain characteristics of the drive speed control section 36 in the controller 30, the responsiveness of the change in the transmission ratio R to the change in the vehicle speed V changes according to the change in the steering wheel angle θH, and the steering wheel steering angle θH increases. When the vehicle is running on a curve, as shown in FIG. 6, when the steering angle θH is small at the beginning or end of the curve,
The responsiveness of transmission ratio changes to changes in vehicle speed becomes more sensitive,
While it is possible to ensure good followability of wheel turning with respect to steering wheel steering, when the steering wheel steering angle θ1 ( It is possible to avoid a sudden change in the transmission ratio R. Therefore, the steering stability of the automobile when traveling on a curve can be improved.

(Effect of Q Ming) As described in Part 2, according to the present invention, in an automatic steering device 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 variable transmission means, By changing the responsiveness of the transmission ratio change to changes in vehicle speed according to the steering wheel angle, the vehicle speed at large steering angles can be maintained while maintaining good followability of wheel turning to steering wheel steering at small steering angles. It is possible to suppress sudden changes in the transmission ratio due to changes, and it is possible to improve steering stability when the vehicle runs on curves.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, and FIG. 1 is a perspective view showing the overall structure of the steering device, FIG. 2 is a sectional view showing the structure of the variable transmission means, and FIGS.
5 is a block diagram showing the configuration of the controller, and FIG. 6 is an explanatory diagram showing the state of changes in the steering angle when the automobile is curved or traveling. DESCRIPTION OF SYMBOLS 1... Steering handle, 3... Steering gear device, 8... Wheels, 9... Variable transmission means, 1
3... Planetary gear mechanism, 20... Stepping motor, 30... Controller, 31... Steering wheel steering angle sensor, 32... Vehicle speed sensor, 36... Drive speed control section.

Claims (2)

[Claims] (1) A transmission ratio variable means that is provided in a steering force transmission path that transmits the steering force of the steering wheel to the wheels via the steering gear device, and that changes the transmission ratio of the wheel steering angle to the steering wheel steering angle, and the transmission ratio The controller includes a controller that controls the operation of the variable means in accordance with the vehicle speed, and a steering angle detection means that detects the steering angle, and the controller controls the operation of the variable means according to the steering angle according to the signal from the steering angle detection means. A steering device for an automobile, characterized in that it is configured to change the responsiveness of a change in transmission ratio to a change in vehicle speed. (2) The steering device for an automobile according to claim (1), wherein the controller changes responsiveness such that the rate of change in the transmission ratio with respect to a change in vehicle speed decreases as the steering angle of the steering wheel increases.