JPS6246769A - Steering device for car - Google Patents

Abstract

PURPOSE:To improve the traveling stability of a car by setting the responsiveness in the variation of transmission ratio for the variation of car speed lower than the responsiveness in the variation of the transmission ratio for the variation of 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 set relatively lower than the responsiveness in the variation of the transmission ratio for the variation of the steering angle of the steering wheel according to the gain characteristic of the driving-speed control part in the controller 30. Therefore, the sharp variation of the transmission ratio for the variation of the car speed is avoided.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a steering device in which the transmission ratio (reduction ratio) of a wheel steering angle to a steering wheel steering angle of an automobile is changed by 1q.

(Prior Art) In general, a steering device/device for an automobile converts the rotational motion of a steering wheel into a lateral displacement motion of a tie rod through a steering wheel device such as a rack-and-binion. Although it changes the direction of the connected left and right steering wheels, the amount of rotation of the steering handle (handle steering angle) and the turning angle of the wheels (wheel steering angle) are usually always maintained in a constant correspondence relationship. ing. 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.

Therefore, in order to meet such requirements, as disclosed in Japanese Patent Application Laid-open No. 58-224852, for example,
A vehicle speed-sensitive steering column 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 is equipped with a Pell 1-type continuously variable transmission mechanism consisting of a pair of opposing variable pitch boots and a V-belt wrapped between both boots between the steering handle and the steering column.
The pitch diameter of the driven side boob 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, and as a result, the turning angle of the wheels with respect to a constant steering wheel steering angle is small at high speeds, becomes large at low speeds, and Good steering characteristics corresponding to this will be reduced by 1q.

(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 automobile 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 change the transmission ratio gradually to improve running stability.

The present invention has been made in view of the above points, and an object of the present invention is to control the change in the transmission ratio with respect to the medium speed and the steering angle when the transmission ratio is variably controlled according to the vehicle speed and the steering angle. By creating a difference in each responsiveness, the vehicle runs while suppressing sudden changes in the transmission ratio due to changes in vehicle speed, without impairing the responsiveness of wheel turning to steering wheel steering. The purpose is to make it possible to improve stability.

(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 is comprised of, for example, a planetary gear mechanism, a differential gear mechanism, etc., and an actuator such as a stepping motor for controlling the operation of the gear mechanism. Furthermore, a controller is provided to control the operation of the transmission ratio variable means in accordance with the vehicle speed and steering angle of the automobile, and the controller is set to control the responsiveness of the transmission ratio change to a change in vehicle speed, and to adjust the responsiveness of the transmission ratio change to a change in the steering wheel angle by setting the controller. Configure to lower responsiveness.

(Operation) Therefore, in the present invention, with the above configuration, when the steering wheel is steered to turn the wheels, the transmission ratio variable means is actuated and controlled by the controller according to the vehicle speed and the steering wheel angle. The transmission ratio of the wheel steering angle is variably controlled.

In that case, in the above controller, the responsiveness of transmission ratio changes to changes in vehicle speed is set to be lower than the responsiveness of transmission changes to changes in steering wheel angle. Even if the responsiveness of the transmission ratio change to the steering angle is increased, the responsiveness of the transmission ratio change to the vehicle speed change will remain relatively low, and the transmission ratio will not change suddenly with the vehicle speed change. As a result, the improvement in driving stability is maintained.

(Example) Hereinafter, embodiments of the present invention will be explained 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, bit, man arm 5. The left and right steering wheels 8 are connected to the left and right steering wheels via a link consisting of tie rods 6, etc. and an i-structure 7.
.
A transmission ratio variable means 9 for changing the transmission ratio R of W is provided.

As shown in enlarged detail in FIGS. 2 to 4, the transmission ratio variable 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 includes a sun gear 14 fixed to the input shaft 12 and a ring gear 1 fixed to the intermediate shaft 4.
5, and for example, three planetary binions 16, 16, . ,16. . . . are pinion shafts 17, 17, . It is carried through... Further, a sector gear 19 is formed on the binion carrier 18, and a binion 21 fixed to a rotation output shaft 20a of a stepping motor 20 is meshed with the sector gear 19. The carrier 1 is rotated around the input shaft 12.
Planetary Binion 16 carried by 8.16. ...
The vinyl A16, 16. By controlling the amount of rotation from the handle shaft 2 or sun gear 14 to the ring gear 15a3 and the intermediate shaft 4 by increasing or decreasing the rotation amount by the movement of..., the transmission ratio R of the wheel steering angle θW to the steering wheel steering angle θH is changed. ing.

On the other hand, 30 is a controller comprising a computer that outputs a control signal to the transmission ratio variable means 9 to control the operation of the stepping motor 20.
0 is the steering wheel angle θH of the steering wheel 1.
Output signals from a steering wheel angle sensor 31 that detects the vehicle speed V (vehicle speed) and a vehicle speed sensor 32 that detects the vehicle speed V (vehicle speed) are input. As shown in detail in FIG. 5, the controller 30 controls the steering wheel steering angle θ detected by the steering wheel angle sensor 31 and the vehicle speed sensor 32, respectively.
H and vehicle speed ■, as shown in Fig. 6, by adjusting the steering wheel angle θ.
The transmission ratio R of the wheel steering angle θW with respect to H is compared with a characteristic map set in advance so that, for example, it is large at high vehicle speeds and small at low vehicle speeds, and the target transmission ratio R is determined by the transmission ratio variable means 9. Based on the output signal of the calculation unit 34, It has a motor drive unit 35 that drives the stepping motor 20 using a pulse signal so that the actual rotation angle of the stepping motor 20 detected by the motor rotation angle sensor 33 matches the target control amount θM calculated above. The configuration of this controller 30 is such that the stepping motor 20 of the variable transmission ratio means 9 is controlled in accordance with the heavy speed V and the steering angle θH.

Further, the controller 30 is provided with a drive speed control section 36 that controls the drive speed υM of the stepping motor 20 according to the vehicle speed V and the steering wheel angle θH. The drive speed control unit 3G compares the actual steering wheel angle θH and vehicle speed V detected by the steering wheel angle sensor 31 and the vehicle speed sensor 32 with a preset characteristic map to determine the actual steering angle θ. (and calculates the motor drive speed υ corresponding to the actual vehicle speed V, and changes the number of pulses of the motor drive pulse signal in the motor drive unit 35 within a certain period of time so that the motor drive speed OM is obtained. The characteristic map read by the drive speed calculating section 36 is based on the characteristics of the motor 20 as the vehicle speed changes.
The gain when the driving speed is changed is the steering angle θ
The gain is set to be lower than the gain when changing the drive speed of the motor 20 in accordance with changes in
With this setting, the responsiveness of a change in the transmission ratio to a change in vehicle speed is lower than the responsiveness of a change in the transmission ratio to a change in steering wheel angle.

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 transmission ratio variable means 9.
The signal is transmitted to the yfi star gear mechanism 13 to rotate the sangi \714. Further, the steering wheel steering angle θ 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 3.
The controller 30 that receives the output signals from both sensors 31 and 32 outputs a control signal to the stepping motor 20 of the transmission ratio variable means 9 to control the rotation of the motor 20. As a result, the binion carrier 18 in the planetary gear mechanism 13 is rotationally driven via the binion 21F3 and the sector gear 19. That is, in the transmission ratio variable 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 binion carrier 18 rotates through the controller 30.
The rotation angle of the stepping motor 20 is controlled by the rotation angle of the stepping motor 20 . Therefore, the ring gear 15 of the transmission ratio variable means 9 and the intermediate shaft 4 integrated therewith rotate by an angle that increases or decreases the rotation angle of the binion carrier 18 with respect to the steering angle θH, and the intermediate shaft 4
The wheels 8.8 are steered by the rotation of the vehicle, whereby the transmission ratio R of the wheel steering angle θW to the steering wheel steering angle θH is variably controlled in accordance with 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 a change in the vehicle speed V is relatively higher than the responsiveness of the change in the transmission ratio R to a change in the steering wheel angle θH. Since the transmission ratio R is set low, it is possible to avoid sudden changes in the transmission ratio R due to changes in the vehicle speed V, while increasing the responsiveness of the wheel turning to the steering wheel in order to match the steering characteristics to the driver's intention. The driving stability of the automobile can be improved and maintained.

In the above embodiment, by setting the gain of the drive speed change of the motor 20 with respect to a change in vehicle speed lower than the same gain with respect to a change in steering wheel angle, the responsiveness of the transmission ratio R is made slower with respect to the vehicle speed V, and the steering wheel Although it is made to be sensitive to the steering angle θH, by changing the transmission ratio based on data while the vehicle speed ■ detected at certain time intervals is changing, the transmission to the vehicle speed V can be made more sensitive. It is also possible to reduce the responsiveness of ratio changes.

That is, instead of controlling the drive speed of the motor 20 by the drive speed control section 36 of the controller 3o as in the above embodiment, the target controller θ of the motor 20 is controlled by the control procedure shown in FIG. It is assumed that the motor 20 is driven so that the opening is determined to be within the control range ωθ. To explain the above control procedure, first, in step S1, the vehicle speed V and the steering wheel steering angle θH detected by the vehicle speed sensor 32 and the steering wheel steering angle sensor 31 are read, and in the next step S2, the previously read vehicle speed V and the previous time are read. It is determined whether the vehicle speed V' is larger or smaller than the vehicle speed V' read in and stored. When this determination is v=v', the process proceeds to step S3, and the target control Waθx of the motor 20 corresponding to the vehicle speed V and the read steering wheel angle θ1(
θH, V) is calculated based on the map, and then, in step S4, the stepping motor 20 of the variable transmission ratio means 9 is drive-controlled so that the calculated target control amount θ is reached.

On the other hand, the determination in step S2 above is V>V'.

In other words, when the vehicle speed V is increasing, the previous vehicle speed V' is updated to v'・←1 in step S5, and then the process moves to step S7 to set the target corresponding to the steering wheel steering angle θH and the updated heavy speed V'. The control amount θ bar = "(θH, V') is calculated, and then, in step S8, the stepping motor 20 is adjusted so that the calculated control 1ffiθ flash is achieved.
to drive and control.

After that, return to step $2 above, and the judgment is ■-v'
Narumar Stellaf S2. Repeat Ss, 87 and S8.

Further, the determination in step S2 above is V<V'.

That is, when the vehicle speed V is decreasing, the process advances to step S6, where the vehicle speed V' is updated to V'-1, and then the process advances to the above-mentioned steps Sy and Ss, and from then on, until the determination becomes V=v', step S2. S6. S7. Repeat S8. still,
The '1' (=1 km/hour) added or subtracted to the vehicle speed V' in steps Ss and S6 above corresponds to the resolution of data during the change in vehicle speed, and due to restrictions on data handled by computers, this resolution is converted into an integer. For example, if the resolution is set to 0.1 km/hour, that is, 1/10 times 1 km/hour, the vehicle speed V read in step S1 is set to 1 km/hour.
゜It is necessary to double it.

Therefore, with the above control, as shown in FIG. 6, even if the vehicle speed sensor 32 detects a change from the vehicle speed V' to the vehicle speed V, the rotation angle θN of the motor 20 changes from the corresponding value of the vehicle speed V' The variable control is not immediately carried out to the value corresponding to the vehicle speed ■, but it gradually changes while being adjusted by the value corresponding to the above resolution, and as a result, the responsiveness of the transmission ratio change to the vehicle speed change becomes the same as the transmission ratio to the steering angle change. The response is lower than that of the change, and therefore the same effect as in the above embodiment can be obtained.

(Effects of the Invention) As described above, according to the present invention, in the steering device for an automobile, the transmission ratio of the wheel steering angle to the steering wheel steering angle is changed according to the vehicle speed and the steering wheel steering angle by the transmission ratio variable means. By setting the responsiveness of the transmission ratio change to changes in vehicle speed to be relatively lower than the responsiveness of the transmission ratio change to changes in the steering wheel angle, it is possible to drive while maintaining good responsiveness of wheel turning to steering wheel steering. This makes it possible to improve the running stability of the vehicle by matching the steering characteristics to the user's will while suppressing sudden changes in the transmission ratio due to changes in vehicle speed.

[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 transmission ratio variable means, and FIGS.
5 is a block diagram showing the configuration of the controller, and FIG. 6 is a characteristic diagram of a map read by the calculation section of the controller. FIG. 7 is a flowchart showing a routine executed by the controller in another embodiment. DESCRIPTION OF SYMBOLS 1... Steering handle, 3... Steering gear device, 8... Wheels, 9... Transmission ratio variable means, 1
3... Planetary gear mechanism, 20... Stepping motor, 30... Controller, 31... Steering wheel steering angle sensor, 32... Vehicle speed sensor, 36... Drive speed i1
i! I fi1 part.

Claims (1)

[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 a controller that controls the operation of the variable means according to the vehicle speed and the steering wheel angle; A steering device for an automobile, characterized in that the steering device is configured to: