JPS6246767A - Steering device for car - Google Patents

Abstract

PURPOSE:To prevent the inadvertent steering of wheels due to the flutuation of a steering wheel by disabling the variable control of the transmission ratio, when the steering angle of the steering wheel is within a minute range, 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 turned. 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 steering angle of the steering wheel is in a nonsensitive band set within a prescribed angle range in the vicinity of zero, the controller 33 does not output a control signal into the motor, and the transmission ratio is kept constant. The steering angle of a wheel is kept constant, even if the steering wheel 1 fluctuates within the range of the nonsensitive band, and the traveling stability can be secured.

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 a wheel steering angle to a 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 turning angle of the wheels (
(wheel steering angle) is normally 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 of the wheel steering angle to the above-mentioned steering wheel steering angle to reduce the magnitude 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 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 boobies and a V-belt wrapped around both boobies, and the pitch diameter of the driven boob. is controlled by a stepping motor 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.

(Problem to be Solved by the Invention) By the way, if the transmission ratio of the wheel steering angle to the steering wheel steering angle is variably controlled in accordance with the vehicle speed, etc., the driver is no longer required when the automobile is traveling straight. When you operate the handle and the handle changes slightly,
In response to this change, the transmission ratio is immediately variably controlled and the wheels are steered. Therefore, countermeasures are desired to ensure running stability.

The present invention has been made in view of the above points, and its object is to perform variable control of the transmission ratio of the wheel steering angle to the steering wheel steering angle when the steering wheel steering angle is within the minute steering angle range. The purpose of this is to prevent the wheels from being unnecessarily steered even if the steering wheel angle changes slightly when the automobile is traveling straight, thereby improving running stability.

(Means for Solving the Problems) In order to achieve the above object, the solving means of the present invention provides a steering force that transmits the steering force of the steering wheel to the wheels via the steering gear device. A variable transmission means is provided for changing the transmission ratio of the wheel steering angle to the steering angle. This variable transmission means is composed of, for example, a planetary gear mechanism or 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 for detecting the 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 variable means, the controller including: A dead zone is set in which the output of the control signal to the variable transmission means is stopped when the steering wheel steering angle is within the minute steering angle range.

<Function> Therefore, in the present invention, with the above configuration, when the steering wheel is steered to turn the wheels, the steering angle is detected by the steering wheel angle sensor as the steering wheel is steered, and the steering angle sensor detects the steering angle as the steering wheel is steered. The variable transmission means is operated and controlled by the controller that receives the output signal from the controller, and the transmission ratio of the wheel steering angle to the steering wheel steering angle is variably controlled in accordance with the steering angle of the steering wheel. At this time, a dead zone is set in the controller, and due to this dead zone, when the car is traveling straight and the steering wheel angle is within a small steering angle range centered on zero, the roller control signal is sent to controller 1. Since the output to the variable transmission means is stopped and the transmission ratio is prevented from changing, the wheel steering angle is reliably zero even if the steering wheel slightly wobbles due to an unnecessary operation by the driver when driving straight. Therefore, the driving stability of the automobile is maintained to the utmost.

<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, pitman 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 transmission device that changes the transmission ratio R from the steering wheel steering angle θH to the wheel steering angle θW. Variable means 9 are provided.

As shown in FIGS. 2 to 4 in an enlarged manner, the variable transmission means 9 is disposed facing the intermediate shaft 4 on the same axis, and has a J-3 at the end opposite to the intermediate shaft 4. It comprises an input shaft 12 drivingly connected to the handle shaft 2 via input gears 10.11 that mesh with each other, and a planetary gear mechanism 13 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, a ring gear 15 fixed to the intermediate shaft 4, and a gear A14.15 between the two gears 14 and 15.
For example, three planetary binions 16, 16, . ... are the pinion shafts 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°1G carried by 8,...
are rolled between sun gear 14 and ring gear 15, and these pinions 16, 16 . By controlling the amount of rotation from the steering wheel shaft 2 or sun gear 14 to the ring gear 15 and intermediate shaft 4 by increasing or decreasing W due to the rolling of..., the center wheel steering angle θW relative to the steering wheel steering angle θ)i is controlled. It is configured to change the transmission ratio R.

On the other hand, 33 is a controller consisting of a computer which outputs a control)1 signal to the transmission variable means 9 to control the operation of the stepping motor 20.
- The roller 33 receives output signals from a steering angle sensor 30 consisting of an encoder that detects the steering angle θI (of the steering wheel 1) and a vehicle speed sensor 31 that detects the vehicle speed of the automobile. As shown in detail in FIG. 5, the controller 33 sets the steering wheel angle θH and vehicle speed V detected by the sensor 30 and the vehicle speed sensor 31, respectively, in advance as shown in FIG. Control is performed by the transmission variable means 9 by comparing and comparing with the characteristic map stored in the characteristic storage section 32. Then the stepping motor 20
and a motor drive section 35 that drives the rotation angle so as to match the rotation angle corresponding to the target transmission ratio R calculated above. The above characteristic map is based on the steering wheel angle OH as shown in the figure.
The transmission ratio R of the wheel steering angle θ·N is set to become smaller as the steering wheel steering angle θH exceeding the dead zone Z increases and as the vehicle speed decreases. Therefore, when the steering wheel steering angle θH, which occurs when the vehicle is traveling straight, is within a range in which the steering wheel steering angle θH changes from zero to the left and right, the controller roller 33 changes the transmission variable means 9 of the control signal.
A dead zone Z is set in which the output to the steering wheel 1 is stopped, and this dead zone Z prevents the above-mentioned transmission ratio R from changing even if the handle 1 wobbles.

Therefore, in the above embodiment J5, when the steering wheel 1 is turned while the automobile is running, the movement is transmitted to the input shaft 1 in the variable f-stage 9 via the steering wheel shaft 2.
2, and the sun gear 14 of the planetary gear mechanism 13 rotates. Further, the steering wheel steering angle 0) (which changes with the steering of the steering wheel 1) is detected by the steering wheel steering angle sensor 30, and the vehicle speed V at that time is detected by the vehicle speed sensor 314.
1 is detected, and a control signal is output from the controller 33, which receives the output No. 6 of these sensors 30 and 31, to the stepping motor 20 of the variable transmission means 9 to control the rotation of the motor 20. The rotation of the motor 20 rotationally drives the pinion carrier 18 in the planetary gear mechanism 13 via the shaft 21 and the locking gear r19. That is, in the transmission variable means 9, the sangi r1
4 rotates by an angle proportional to the steering angle θH of the handle 1, and at the same time, the binion carrier 18 rotates between the controller 1 and the roller 33.
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 variable transmission ratio 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 this intermediate shaft 4
The wheels 8.8 are steered by this rotation, and thereby the transmission ratio R of the wheel steering angle θW to the steering wheel steering angle θH is variably controlled.

In that case, the wheel steering angle θW with respect to the above-mentioned steering wheel steering angle θH
The transmission ratio R is determined by the controller 33 to become smaller as the steering wheel angle θH increases and as the vehicle speed V decreases, as shown in FIG. 6, but as shown in FIG. When in the dead zone Z within a predetermined angle range (within a minute steering angle range) in the vicinity thereof, no control signal is output from the controller 33 to the stepping motor 20 of the variable transmission means 9, and the transmission ratio R does not change. . Therefore, even if the steering wheel 1 wobbles within the dead zone Z due to an operation that does not generate driving noise while driving straight, the wheel steering angle θW remains unchanged and remains at zero, thereby ensuring sufficient driving stability. It is possible.

In the above embodiment, the transmission ratio of the wheel steering angle to the steering wheel angle is variably controlled in accordance with the vehicle speed, but it may also be variably controlled in accordance with the steering speed of the steering wheel.

(Effects of the Invention) As described above, according to the present invention, in the automobile steering device in which the transmission ratio of the wheel steering angle to the steering wheel steering angle is changed by the transmission variable means, the steering angle of the steering wheel is small. By disabling variable control of the transmission ratio when the transmission ratio is within the range, even if the steering wheel wobbles due to an unnecessary operation by the driver while driving straight and a slight change in the steering angle occurs, the effect will be less on the wheels. Therefore, running stability can be sufficiently ensured.

[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 a characteristic diagram of the map read by the calculation section of the controller. DESCRIPTION OF SYMBOLS 1... Steering handle, 3... Steering gear device, 8... Wheels, 9... Variable transmission means, 1
3...3'fi star gear mechanism, 20...Stepping motor, 30...Handle steering angle sensor, 33...Controller, Z...Dead zone. Go to □□111 Patent applicant Mazda Motor Corporation 1st generation
Rinto Mae 1) Hiroshi ・2,'1--'-・Figure 5Figure 6

Claims (1)

[Claims] (1) A variable transmission ratio 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; The controller includes a steering wheel steering angle sensor that detects a steering angle, and a controller that inputs an output signal from the steering wheel steering angle sensor and outputs a control signal to the transmission ratio variable means. 1. A steering device for an automobile, characterized in that a dead zone is provided for stopping output of a control signal to the transmission ratio variable means when the steering angle is within a range from zero to a minute steering angle.