JPS6246774A - Steering device for car - Google Patents

Abstract

PURPOSE:To improve the traveling stability in high and low speed ranges by reducing the variation of the transmission ratio in the high speed range over the first set car speed and the low speed range below the second set car speed to zero, in the variation of the transmission ratio of the steering angle of wheels for the steering angle of a 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 a 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 30 and 31, and a controller 33 controls the revolution of a stepping motor of the transmission-ratio varying means 9 according to the above-described output signals. In this case, if the car speed is in the high- speed range over the first set car speed or the low-speed range below the second set car speed, the controller 33 performs control so that the variation of the transmission ratio becomes zero. Therefore, the increase of the variation of the behavior of a chassis in high-speed traveling or the variation of the steering angle of a wheel in low speed traveling is prevented.

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. It changes the direction of the left and right steering wheels, but the amount of rotation of the steering wheel (handle steering angle) and the steering angle of the wheels (
Wheel steering angle〉/distortion Normally, a constant correspondence relationship is maintained at all times. However, for example, when a car is running at high speed, it is desirable to increase the transmission ratio of the wheel steering angle to the above-mentioned steering wheel steering angle and to reduce the size of the wheel steering angle with respect to a constant steering wheel steering angle, in order to ensure driving stability. , When driving at low speeds, the car's behavior is made more agile and a good driving feeling is achieved! ? From the viewpoint of making it easier to store the vehicle in a garage, etc., it is desirable to conversely reduce the -12 transmission ratio and increase the wheel steering angle with respect to a constant steering wheel steering angle.

Therefore, in order to meet such requirements, as disclosed in Japanese Patent Application Laid-open No. 58-224852, for example,
A speed-sensitive steering device has been proposed that changes the transmission ratio of the wheel steering angle to the steering wheel steering angle in accordance with the vehicle speed of the automobile. This system is equipped with a transmission mechanism between the steering handle and the steering column, consisting of a pair of opposing variable pitch bobbies and a V-belt wrapped between both bobbles, and the pitch diameter of the driven pulley is adjusted. The stepping motor controls the speed so that it increases 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 relative to a constant steering wheel steering angle becomes small at high speeds and large at low speeds, and as the vehicle speed increases. Corresponding good steering characteristics can be obtained.

<Problems to be Solved by the Invention> However, when the transmission ratio is changed in accordance with the vehicle speed as described above, the following problems occur.

In other words, in the high vehicle speed range, the steering angle of the wheels relative to a constant steering angle is reduced to reduce the effect of the steering wheel on the steering of the middle wheels, but if the transmission ratio changes while driving at high speeds, Even if the amount of wheel turning is the same as the amount of wheel turning during low speed driving, the behavior of the vehicle body becomes greater than in the low speed range, and improvements are desired in order to increase driving stability.

In addition, in a low vehicle speed range where the turning angle of the wheels relative to a constant steering angle becomes large, for example, when stopping the vehicle, the transmission ratio changes during the period from low speed traveling to stopping. The behavior of the vehicle becomes more agile than necessary, resulting in a decrease in maneuverability.

The present invention has been made in view of the above points, and its object is to set the transmission ratio of the wheel steering angle to the above-mentioned steering wheel steering angle to be variably controlled only in a specific range of vehicle speed. The objective is to improve running stability in a high vehicle speed range and handling stability in a low vehicle speed range.

(Means for Solving the Problems) In order to achieve the second object, the solution means of the present invention includes a steering force transmission path that transmits the transmission 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 steering wheel. This transmission ratio variable means is composed of, 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 centering mechanism. Further, a vehicle speed detection means for detecting vehicle speed and a controller for inputting a signal from the vehicle speed detection means and outputting a control signal for controlling the operation of the transmission ratio variable means are provided, and the controller causes the vehicle speed to exceed a first set vehicle speed. The transmission ratio is variably controlled in an intermediate range excluding a high speed range and a low speed range below a second set vehicle speed which is lower than the first set vehicle speed.

(Function) Therefore, in the present invention, with the above configuration, when the steering wheel is steered to turn the wheels, the vehicle speed at that time is detected by the vehicle speed detection means, and the controller receives the output of the detection means. The transmission ratio variable means is operated and controlled based on the signal, and the transmission ratio of the wheel steering angle to the steering wheel steering angle is variably controlled in accordance with the vehicle speed.

In that case, the above-mentioned transmission ratio is variably controlled by the controller according to the vehicle speed only in the single chain intermediate range, but in the high speed range above the first set vehicle speed and below the second set vehicle speed which is lower than the first set vehicle speed. In the low speed range, the transmission ratio is not variable controlled by the controller, and the transmission ratio is kept constant at a predetermined value corresponding to each speed range. Therefore, even when the vehicle is being handled at high speed, the vehicle body does not move significantly, and driving stability is improved. Furthermore, even when the vehicle is handled at low speeds, the middle wheel steering angle does not change significantly, improving maneuverability.

<Example> Hereinafter, embodiments of the present invention will be described 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, pitman arm 5. tie rod 6
The left and right steering wheels 8.8 are connected via a link mechanism 7 consisting of a
The steering gear device is connected to a steering gear device, and a variable transmission ratio is provided in the steering force transmission path between the steering wheel 1 and the steering gear device 3 to change the transmission ratio R of the wheel steering angle θW to the steering wheel steering angle θH. Means 9 is installed.

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 connected 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. Above T! The star tooth width structure 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 31, for example, arranged at equal angular intervals between the two gears 14 and 15 so as to mesh with both the gears 14 and 15, respectively.
[n planetary binions 16, 16, . . . and the binions 16. ,16. ... is the pinion shaft 17.17.
... and a binion carrier 18 which is supported on the input shaft 12 and externally fitted rotatably on the input shaft 12. Further, a sector gear 19 is formed on the binion carrier 18, and a binion 21 fixed to a rotating shaft 20a of a stepping motor 20 is meshed with the sector gear 19, and the rotation of the stepping motor 20 inputs the output of the binion carrier 18. The carrier 1 is rotated around the axis 12.
Planetary binion 16°16 carried by 8,...
transferred between sun gear 14 and ring gear A715,
This binion 16.16. ... is configured to change the transmission ratio R of the wheel steering angle θW to the steering wheel steering angle θH by controlling the amount of rotation from the handle shaft 2 or sun gear 14 to the ring gear 15 and the intermediate shaft 4 by increasing or decreasing the rolling of the steering wheel. has been done.

On the other hand, 33 is a controller consisting of a computer that outputs control number 13 to the transmission ratio variable means 9 to control the operation υ of the stepping motor 20. Output signals from a steering wheel steering angle sensor 30 consisting of an encoder for detecting the vehicle speed and a vehicle speed sensor 31 serving as a vehicle speed detecting means for detecting the vehicle speed (2) of the automobile are inputted. As shown in detail in FIG. 5, the controller 33 sets the steering wheel angle θH and vehicle speed V detected by the steering wheel angle sensor 30 and vehicle speed sensor 31, respectively, as shown in FIG. 6 in advance. A target transmission ratio calculating section 34 calculates a target transmission ratio R to be controlled by the transmission ratio variable means by comparing and comparing with the characteristic map stored in the characteristic storage section 32; a motor drive unit 3 that drives the stepping motor 20 so as to match the rotation angle corresponding to the calculated target transmission ratio R;
It consists of 5. The above characteristic map is set such that the transmission ratio R of the wheel steering angle θW to the steering wheel steering angle θH increases as the vehicle speed V increases in the single-engine intermediate range, and at the same time, the transmission ratio R of the wheel steering angle θW to the handle steering angle θH increases as the vehicle speed V increases The change is set to zero in a high speed range and a low speed range below a second set vehicle speed v2 which is lower than the first set vehicle speed v1.

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 sun gear 14 of the 'fi star gear mechanism 13 rotates. 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 30, and the vehicle speed at that time is detected by the vehicle speed sensor 31.
The controller 33 receives the output signals of both the sensors 30 and 31 and outputs the transmission ratio variable means 9.
A control signal is output to the stepping motor 20 to control the rotation of the motor 20, and the rotation of the motor 20 rotationally drives the binion carrier 18 in the planetary gear mechanism 13 via the binion 21 and sector gear 19. That is, in the transmission ratio variable means 9, the sun gear 14
is rotated by an angle proportional to the steering angle OH of the handle 1, and at the same time, the binion carrier 18 is rotated according to the rotation angle of the stepping motor 20 controlled by the controller 1-roller 33. For this reason, the transmission ratio variable means 9
The ring gear 15 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 rotation of the intermediate shaft 4 causes the wheels 8, 8 to be steered. As a result, the transmission ratio R of the wheel steering angle θW to the steering wheel steering angle θ11 is variably controlled.

In that case, the vehicle speed at this time is not shown in the characteristic map of FIG.
When the vehicle is in a low speed range below the second set vehicle speed v2, which is lower than Also, it is possible to prevent the change in the middle wheel steering angle from becoming large during low-speed driving, and thus it is possible to improve driving stability and steering stability.

(Effects of the Invention) As described above, according to the present invention, in the steering device for an automobile in which the transmission ratio of the wheel steering angle to the steering wheel steering angle is changed by the transmission ratio variable means, the above transmission is performed only in the single intermediate range. The ratio is variably controlled, and the change in the transmission ratio is zero in the high speed range above the first set vehicle speed and the low speed range below the second set vehicle speed, which is lower than the first set vehicle speed. It is also possible to improve running stability and handling stability in low speed ranges.

[Brief explanation of drawings]

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 the map read by the sieve section of the controller. 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, 31... Vehicle speed sensor, 33... Controller. -゛) Patent applicant: Mazda Motor Corporation: Agent 1)
Hiroshi・---ノ1 Figure 5 Figure 6 Large

Claims (1)

[Claims] (1) A transmission ratio variable means is provided in the steering force transmission path that transmits the steering force of the steering wheel to the wheels via the steering gear device, and changes the transmission ratio of the wheel steering angle to the steering wheel steering angle, and detects the vehicle speed. a controller for inputting a signal from the vehicle speed detecting means and outputting a control signal for controlling the operation of the transmission ratio variable means; A steering device for an automobile, characterized in that the transmission ratio is variably controlled in an intermediate range excluding a low speed range and a second set vehicle speed lower than the first set vehicle speed.