JPS6246773A - Steering device for car - Google Patents

Abstract

PURPOSE:To obtain the stable handling performance by prohibiting the variation of the transmission ratio accompanied by the variation of car speed when the steering angle of a steering wheel exceeds the minute steering angle close to zero, in the variation of the transmission ratio of the steering angle of a wheel 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 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 steering angle of the steering wheel exceeds a center region having a minute steering angle close to zero, the variation of the transmission ratio, accompanied by the car-speed variation is prohibited by the controller 33. Therefore, the relation between the steering angle of the steering wheel and the steering angle of the wheels can be kept constant, even in case of cornering where the steering angle of the steering wheel increases or if the car speed varies.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a steering device that can change the transmission ratio (reduction ratio) of the wheel steering angle to the 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 it depends on the steering wheel angle (listening to the rotation of the steering wheel) 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 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 transmission ratio is conversely reduced to maintain a constant steering angle in order to make the vehicle's behavior more agile and obtain a good driving feeling, or to make it easier to park the vehicle. It is desirable to increase the wheel steering angle relative to the

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 in which the transmission ratio of the wheel steering angle to the steering wheel steering angle is changed in accordance with the vehicle speed of the automobile. In this system, a transmission mechanism is provided between the steering handle and the steering column, consisting of a pair of variable pitch boots facing each other and a swung V-belt between the two boots. The pitch diameter of the wheels 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 relative to a constant steering wheel steering angle becomes small at high speeds and large at low speeds, and as the vehicle speed increases. The correspondingly good steering characteristics will be reduced by 1q.

(Problem to be Solved by the Invention) However, in the above-mentioned conventional vehicle, the transmission ratio changes depending on the vehicle speed, so even if the steering amount of the steering wheel is constant while driving, the amount of rotation of the middle wheel varies depending on the vehicle speed. As a result, it is difficult to grasp the steering feeling during cornering, etc., and it is difficult to obtain stable handling performance.

The present invention has been made in view of the above points, and an object thereof is to prevent the above-mentioned transmission ratio from changing in accordance with changes in vehicle speed when steering the steering wheel during cornering, etc., so that the steering wheel steering angle can be reduced. The purpose is to maintain a constant relationship between the steering wheel angle and the wheel steering angle, thereby achieving stable handling performance during cornering and the like.

(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 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 ms mechanism. Furthermore, a steering wheel steering angle detection means for detecting a steering wheel steering angle;
A controller is provided to control the transmission ratio variable means in accordance with vehicle speed. Then, an output signal from the steering wheel angle detection means is inputted to the controller 1 roller, and when the steering wheel steering angle exceeds a minute steering angle near zero, the transmission ratio of the transmission ratio variable means due to a change in vehicle speed is determined. The configuration includes a prohibition means for prohibiting changes in

(Function) 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 changing the wheel steering angle relative to the steering wheel steering angle. The transmission ratio is variably controlled.

In that case, the steering wheel steering angle is detected by the steering wheel steering angle detecting means, the output signal of this detecting means is inputted to the controller described below, and as long as the steering wheel steering angle is within the minute steering angle range near zero, the controller The inhibiting means does not operate and the transmission ratio is variably controlled as the transmission ratio variable means changes medium speed, and when the steering wheel steering angle exceeds the minute steering angle, the inhibiting means prohibits the transmission ratio from changing. . Therefore, even if the vehicle speed changes during cornering or the like where the steering angle changes greatly, the transmission ratio does not change, and stable handling performance can be obtained.

(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 at the center, and 3 is a steering handle connected to the round end of the handle shaft 2 via an intermediate shaft 4. At the same time, pitman arm 5. tie rod 6
The links consisting of the left and right steering wheels 8, 8 are connected via the lever 7.
The steering gear device is connected to the steering wheel 1 and the steering gear device 3, and a wheel steering angle θW relative to the steering wheel steering angle θF is located in the middle of the steering force transmission path between the steering wheel 1 and the steering gear device 3.
A transmission ratio variable means 9 is provided for changing the transmission ratio R of.

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 15 fixed to the intermediate shaft 4.
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 pinion chirelia 18, and the sector gear r19 has a rotating shaft 2 of the stepping motor 20.
A pinion 21 fixed to the pinion carrier 1 is engaged with the pinion carrier 1 by rotation of the stepping motor 20.
8 around the input shaft 12, and attach the corresponding key (1 to the rear 18).
The planetary pinions 16, 16, . . Due to the rolling of..., the handle shaft 2
or sun gear 14 to ring gear 15 and intermediate shaft 4
The transmission ratio R of the middle wheel steering angle θW to the steering wheel steering angle θH is changed by increasing/decreasing the rotation amount until the rotation amount reaches .

On the other hand, 33 is a controller consisting of a computer which outputs a control signal to the transmission ratio variable means 9 to control the operation of the stepping motor 20.
Output signals from a steering wheel steering angle sensor 30 as a steering wheel angle detecting means for detecting H and a vehicle speed sensor 31 as a vehicle speed detecting means for detecting the traveling speed V (vehicle speed) of the automobile are input. As shown in detail in FIG. 5, the controller 33 compares and compares the steering wheel angle θH and vehicle speed V detected by the steering wheel angle sensor 30 and the vehicle speed sensor 31, respectively, with a preset characteristic map. Then, the transmission ratio variable means 9 determines the controlled target transmission ratio R, and the target control amount (rotation angle) of the stepping motor 20 corresponding to the target transmission ratio R is determined as θx=f(θH, V
), and a control amount calculation unit 37 that calculates the stepping motor 20 based on the output signal of the calculation unit 37, and a control amount calculation unit 37 that calculates the stepping motor 20 based on the output signal of the calculation unit 37.
a motor drive section 38 that is driven by a pulse signal so that the actual rotation angle of the motor matches the calculated target control 1h;
Upon receiving the output signal from the above-mentioned steering wheel steering angle sensor 30, it is detected whether the current steering wheel steering angle θi is within the center region ΔθH, which is a minute steering angle near zero, as shown in FIG. , when the steering wheel steering angle θH exceeds the center region ΔθH, outputs a detection signal to the calculation section 37, and inhibits the transmission ratio variable means 9 from changing the transmission ratio R due to a change in vehicle speed. It consists of a region detection section 39. The characteristic map read by the calculation unit 37 is based on the transmission ratio R of the wheel steering angle θW to the steering wheel steering angle θ1→.
is set to be large at high vehicle speeds and small at low vehicle speeds, for example.

Here, the procedure of signal processing performed in the controller 33 will be further explained with reference to the flowchart shown in FIG. First, in step S1, the actual steering wheel steering angle θH detected by the steering wheel steering angle sensor 30 is read, and in step S2, the center area detection unit 39 determines whether or not the steering wheel steering angle θF (is within the center area ○H). to judge.

If this determination is YES, the process advances to step S3, and in step S3, the vehicle speed V detected by the vehicle speed sensor 31 is
Load. Next, in step S4, the calculation unit 37 compares the steering wheel steering angle θl-I3 and the vehicle speed V with the characteristic map to calculate a target transmission ratio R to be controlled by the transmission ratio variable means, and in step S5, the target transmission ratio R is calculated. The target control til]K5-OM of the stepping motor 20 corresponding to R is calculated. After that, the process proceeds to step S6, and the stepping motor 20 is adjusted so that the target control amount θ is calculated as described above.
Drive 8.

On the other hand, if the determination in step $2 is No because the steering wheel angle θH exceeds the center area ΔθH, the process proceeds to step S7, and the calculation is performed immediately before the steering wheel steering angle θH increases from zero and exceeds the center area ΔθH. The previous transmission ratio R is read, and then the process proceeds to step S5 to calculate the control amount of the stepping motor 20 for this transmission ratio R, and then, in step S6, the stepping motor 20 is driven in the same manner as described above.

Therefore, due to the control characteristics described above, the controller 33 uses its center region detecting section 39 to detect, as shown in FIG. While allowing the change in the transmission ratio R due to the change in vehicle speed of the ratio variable means 9, when the steering wheel steering angle θH exceeds the center region ΔθH, the change in the transmission ratio R is prohibited, and the transmission immediately before exceeding the center region ΔθH is prohibited. It is configured to change the control amount θ of the stepping motor 20 so as to maintain the ratio R.

In the above example, the downward force is when the car is running,
When the steering wheel 1 is steered, its 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 planetary 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 3o, and the vehicle speed (2) at that time is detected by the sensor 31. A control signal is output from the controller 33 that receives the output signal to the stepping motor 20 of the transmission ratio variable means 9 to control the rotation of the motor 20. Width mechanism 1
The binion carrier 18 at 3 is rotationally driven. That is, in the transmission ratio variable means 9, the sun gear 14 is rotated by an angle proportional to the steering angle θH 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 33. Become so. Therefore, the ring gear V15 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 rotation of the intermediate shaft 4. As a result, the wheels 8.8 are steered, and as a result, the transmission ratio R of the wheel steering angle θW to the steering wheel steering angle θH is variable controlled 1211 in accordance with the vehicle speed V.

In that case, when the steering wheel steering angle θH is within the center region ΔθH, the center region detection section 39 of the controller 33
does not output the detection signal to the calculation unit 37, and the steering wheel steering angle θ1
The transmission ratio R of the wheel steering angle θW changes as usual according to changes in vehicle speed, but when the steering wheel steering angle θH exceeds the center area ΔθH, the detection signals of the three center area detection units are output to the calculation unit 37. Therefore, even if the vehicle speed changes during cornering where the steering wheel steering angle θ1→ increases, the transmission ratio R does not change and the steering wheel steering angle θH increases. The relationship between the wheel steering angle θW and the wheel steering angle θW is kept constant, and thereby stable handling performance can be obtained.

(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 steering wheel steering angle is detected, When the steering wheel steering angle exceeds a minute steering angle near zero, the prohibition means of the controller prohibits the transmission ratio variable means from changing the transmission ratio due to changes in vehicle speed, so that the vehicle speed changes during cornering etc. However, the relationship between the steering wheel angle and the wheel steering angle can be maintained constant, and stable handling performance can be obtained.

[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 shows the configuration of the controller. Transmission ratio variable means, 6.
The figure is a flowchart 1 showing a routine processed by the controller, and FIG. 7 is a characteristic diagram illustrating the permissible range of variation of the transmission ratio and the prohibited range of variation in the steering angle. DESCRIPTION OF SYMBOLS 13... Planetary gear mechanism, 2o... Stepping motor, 30... Steering wheel steering angle sensor, 31.°Vehicle speed sensor, 33... Controller, 39... Center area detection unit. Patent applicant: Mazda Motor Corporation
Before Rinto 1) Hiroshi:, 11゜□ -゛su

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 steering wheel steering angle. and a controller that controls the transmission ratio variable means in accordance with the vehicle speed. A steering device for a motor vehicle, characterized in that it has a prohibition means for prohibiting the transmission ratio variable means from changing the transmission ratio due to a change in vehicle speed when the steering wheel is steered so that the steering angle exceeds a minute steering angle in the vicinity of zero.