JPS63240476A - Steering device for automobile - Google Patents

Abstract

PURPOSE:To promote the improvement of running stability, by setting the reference transmission ratio characteristic, determined so that transmission ratio increases higher in accordance with an increase of a car speed, and the transmission ratio characteristic, which changes in accordance with a handle steering angle, and changing their offset value in accordance with the car speed. CONSTITUTION:A controller 11, which variably controls transmission ratio, is constituted of a control amount arithmetic part 26 inputting a signal S1 from a car speed sensor 12 and a signal S2 from a handle steering angle sensor 13 and a driving signal generating part 27 generating a driving signal in accordance with a calculated value obtained in the arithmetic part 26. A signal S3 from the signal generating part 27, serving as the driving signal, is applied to a stepping motor 24, and its rotary amount is detected by a sensor 28 being fed back to the signal generating part 27. The control amount arithmetic part 26, in which the transmission ratio is set so as to increase higher as a car speed V increases larger, calculates a wheel steering angle from the transmission ratio and a handle steering angle, driving the stepping motor 24. Accordingly, an automobile improves its running stability in the time of high speed and controllability in the time of low speed.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a steering device for an automobile, and particularly to a steering device that changes the transmission ratio between the steering wheel angle and the wheel steering angle depending on the vehicle speed and the steering angle. Regarding improvements.

(Prior Art) In general, a steering device for an automobile displaces a tie rod in the lateral direction via a steering gear device such as a rack and pinion by rotating a steering handle. However, the transmission ratio between the rotation angle of the steering handle (handle steering angle) and the turning angle of the wheels (wheel steering angle) is set constant. is customary.

However, for example, when the vehicle is running at high speeds, the transmission ratio (handle steering angle/wheel steering angle) is increased to improve driving stability, and when the vehicle is running at low speeds, the behavior of the vehicle is made agile to provide a good driving feeling. It is desirable to improve maneuverability by lowering the transmission ratio from the viewpoint of making it easier to store the vehicle in a garage or to park it in a garage.

Therefore, there are two things that meet these demands: 1. For example, Japanese Patent Application Laid-Open No. 58-224852 proposes a vehicle speed-sensitive steering device in which the transmission ratio between the steering wheel angle and the wheel steering angle is changed in accordance with the vehicle speed.

On the other hand, there is a predetermined standard transmission ratio characteristic such that the transmission ratio increases as the vehicle speed increases, and the standard transmission ratio characteristic is changed (offset) according to the steering angle.
The transmission ratio characteristic is set to change the transmission ratio when turning suddenly while driving at high speed, etc., so that the transmission ratio is set lower (the wheels tend to cut easily) and the vehicle speed is lowered to avoid danger. A steering angle-sensitive steering device has also been proposed (see Japanese Patent Laid-Open No. 122077/1983).

By the way, in the latter type of steering device that is sensitive to vehicle speed and steering angle, the offset value of the changing transmission ratio characteristic at low speeds is usually set to be larger than that at high speeds. When the steering wheel is turned sharply, such as when parking the vehicle, the transmission ratio changes rapidly, causing a problem in which the feeling deteriorates.

(Object of the Invention) The present invention has been made in order to solve the above-mentioned problems, and particularly aims to prevent sudden changes in the transmission ratio when the steering wheel is turned significantly at low speeds.

(Structure of the Invention) Therefore, the present invention has the following features, as shown in FIG.
Change the transmission ratio between the steering wheel angle and the wheel steering angle in accordance with the output signals of the vehicle speed sensor C and the steering wheel angle sensor D during the steering force transmission path that steers the wheels B in response to the steering wheel A. This is a steering device for an automobile in which a variable transmission means E is provided, which has a predetermined standard transmission ratio characteristic such that the transmission ratio increases as the vehicle speed increases, and the standard transmission ratio characteristic is applied to the steering angle of the steering wheel. A transmission ratio characteristic that is changed according to the vehicle speed is set, and a control means F is provided that changes an offset value of the changed transmission ratio characteristic from the reference transmission ratio characteristic according to the vehicle speed. .

(Effects of the Invention) According to the present invention, in the vehicle speed/steering angle sensitive transmission variable steering device, the control means changes the offset value of the modified transmission ratio characteristic from the base Q transmission ratio characteristic according to the vehicle speed. Because it is designed to
The wheels may break easily), making it easier to avoid danger.
Since the offset value is small at low speeds, the transmission ratio will not change suddenly even if you turn the steering wheel sharply when the car is in the garage, which improves the feeling.

(Example) Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

As shown in FIG. 2, the steering device 1 includes a steering wheel 2, and a steering wheel shaft 3 that rotates the steering wheel 2.
and a steering gear device 5 that is manually operated via the intermediate shaft 4, and left and right steering wheels 6,
The link mechanism 9 includes a pitman arm 7, a tie rod 8, etc. that steers the steering wheel 6.

Between the steering wheel Ni3 and the intermediate shaft 4, there is a rotation angle of the steering handle 2 (handle steering angle: θh) and a wheel 6.
．． 6 steering angle (wheel steering angle; θW) (transmission ratio: R=θ
A transmission pressure variable device IO for changing the transmission pressure (h/θW) is provided.

A controller 11 is provided to control the variable transmission pressure device 10, and the controller 11 receives a signal S indicating the vehicle speed V from a vehicle speed sensor 12 that detects the vehicle speed of the vehicle, and a signal S indicating the vehicle speed V from the vehicle speed sensor 12 that detects the vehicle speed of the vehicle. angle θh
A signal S from the steering angle sensor 13 is input to detect the steering angle.

As shown in detail in FIGS. 3 to 5, the transmission pressure variable device 10 has an input shaft 14 disposed on the same axis as the intermediate shaft 4 and facing the handle. Axis 3
The rotation of the motor is controlled manually through a pair of input gears 15 and 16.

A planetary gear mechanism 17 is interposed between the input shaft 14 and the intermediate shaft 4, and the planetary gear mechanism 17 includes a sun gear 18 fixed on the human power shaft 14,
A plurality of pinion gears 19...19 arranged above,
A ring gear 20 is disposed outside these pinion gears 19...19 and is fixed to the intermediate shaft 4, and is fitted and supported on the input shaft 14 so as to be relatively rotatable, and is connected to the ring gear 20 via the pinion shafts 21...21. Each of the above pinion gears 19
. . 19 and a carrier 22 supporting the carriers 19.

A sector gear 23 is integrally provided on the carrier 22, and a pinion gear 25 fixed to a rotating shaft 24a of a stepping motor 24 is meshed with the sector gear 23.

When the steering wheel 2 is turned, the stepping motor 24 is rotationally driven in accordance with the drive signal S from the controller 11, so that in the planetary gear mechanism 17, the sun gear 18 is rotated by an amount corresponding to the steering wheel steering angle θh. At the same time as the carrier 22 is rotated, the carrier 22 is rotated in accordance with the rotation of the stepping motor 24, and thereby the ring gear 20 or the intermediate shaft 4 corresponding to the wheel steering angle θW is rotated.
The amount of rotation is increased or decreased, and the transmission ratio R of the steering wheel angle θh to the wheel steering angle θW is variably controlled.

On the other hand, the controller 11 that variably controls the transmission ratio as described above is connected to the vehicle speed sensor 12 as shown in FIG.
The signal S1 from the steering wheel angle sensor 13 and the signal S from the steering wheel angle sensor 13 are input to the control amount calculation section 26;
The signal S3 outputted from the signal generating section 27 is used as a driving signal to drive the stepping motor 2.
4, the amount of rotation of the motor 24 is detected by a motor rotation angle sensor 28, and is fed back to the drive signal generator 27 as a feedback signal S4.

Here, the control amount calculation unit 26 sets the transmission ratio R of the steering wheel steering angle to the wheel steering angle θW based on a predetermined characteristic according to the vehicle speed V indicated by the signal S from the vehicle speed sensor 12. , this transmission ratio R and the above steering wheel steering angle θ
A wheel steering angle θW is calculated from the wheel steering angle θW, and a drive signal S is outputted to the stepping motor 24 via the drive signal generating section 27 so that the wheel steering angle θW is obtained.

In this case, the characteristics of the transmission ratio R with respect to the vehicle speed V are set such that the transmission ratio R increases as the vehicle speed V increases (see reference transmission ratio a in FIG. 8).

As a result, when driving at high speeds, the transmission ratio R becomes high and the wheels 6 are difficult to break, so good running stability can be obtained.At the same time, when driving at low speeds, the transmission ratio R becomes low and the wheels 6 are easy to break, so the garage Maneuverability will be improved, such as easier insertion.

In addition, for the reference transmission ratio a in FIG. 8, the reference transmission ratio a
A transmission ratio c is set to change (offset) according to the steering wheel angle θh.

This results in a lower transmission ratio (
The wheels become more prone to breakage), making it easier to avoid danger.
If you turn the steering wheel significantly to park the vehicle at low speeds, the transmission ratio will be lower (the wheels will easily break), making it easier to park the vehicle.

Therefore, the offset value of the changed transmission ratio c at low speeds is set smaller than at high speeds.

As a result, while the effect of sudden steering at high speeds is maintained, when the steering wheel is turned sharply at low speeds, such as when pulling into a garage, the offset value is small, so the transmission ratio and c do not change suddenly, improving the feeling. That's what I do.

The operation of the control amount calculation section 26 will be explained according to the flowchart in FIG. Data (transmission ratios a, b, c) are read from the data (see figure), and in step S4, a drive signal S based on this data is used to drive the stepping motor 24.
to drive and control.

FIG. 9 shows another example of the transmission ratio map, in which the offset values of transmission ratios a, b, and c are set to zero at low speeds.

As a result, the transmission ratio is fixed at low speeds, so there is no change in the transmission ratio at all, further improving the feeling.

[Brief explanation of drawings]

Fig. 1 is a configuration diagram of the present invention, Fig. 2 is a perspective view of the steering device, Fig. 3 is an enlarged longitudinal sectional side view of the variable transmission pressure device, Fig. 4 is a sectional view taken along line I-I in Fig. 3, Figure 5 shows I[
= II line sectional view, Figure 6 is a block diagram showing the configuration of the controller, Figure 7 is a characteristic diagram of control by the controller,
FIGS. 8 and 9 are diagrams showing transmission ratio maps, respectively. DESCRIPTION OF SYMBOLS 1... Steering device, 2... Steering handle (A), 6... Wheel (B), 10... Transmission ratio variable means (E), II... Controller, 12... Vehicle speed sensor CC'), 13... Steering wheel steering angle sensor (D
), 26... Controlled amount calculation t! I! (F: control means)
, θh...Handle steering angle, θW...Wheel steering angle, R・
...Transmission ratio, ■...Vehicle speed, a, b, c...Transmission ratio. Patent Applicant: Mazda Motor Corporation Agent Patent Attorney: Aohaku, Ao, and 2 others Figure 5, Figure 6, Figure 7, Figure 8

Claims (1)

[Claims] (1) A transmission ratio that changes the transmission ratio between the steering wheel angle and the wheel steering angle in accordance with the output signals of the vehicle speed sensor and the steering wheel angle sensor during the steering force transmission path that turns the wheels in accordance with the steering of the steering wheel. A steering device for an automobile in which a variable means is provided, which has a predetermined standard transmission ratio characteristic such that the transmission ratio increases as the vehicle speed increases, and changes the standard transmission ratio characteristic according to the steering angle of the steering wheel. What is claimed is: 1. A steering system for a motor vehicle, wherein a transmission ratio characteristic is set, and a control means is provided for changing an offset value of the changed transmission ratio characteristic from a reference transmission ratio characteristic in accordance with vehicle speed.