JPS6246768A - Steering device for car - Google Patents

Abstract

PURPOSE:To set the behavior always constant by detecting the behavior of a chassis on turning of a car and correcting the transmission ratio according to the behavior, 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 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, the lateral acceleration speed for a chassis on the turning of a car is detected by a sensor 35, and the controller 33 corrects the transmission ratio on the basis of the detection signal. Therefore, the behavior of a chassis accompanied by the car-speed variation at a constant steering angle of the steering wheel is set always constant, and the drivability and operation performance on turning can be improved.

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, an automobile steering device converts the rotational movement of a steering wheel into a displacement of a tie rod in the lateral force direction through a steering gear device such as a rack and pinion.
, and changes the direction of the left and right steering middle wheels connected to both ends of the tie rod. ) are usually always maintained in a constant correspondence relationship. However, for example, when a car is running at high speed, it is important to increase the transmission ratio from the steering wheel steering angle to the wheel steering angle to reduce the wheel steering angle for a constant steering angle in order to ensure driving stability. On the other hand, when driving at low speeds, the above transmission ratio is conversely reduced to maintain a constant steering angle in order to make the vehicle's behavior more agile and provide a good driving feeling, or to make it easier to park the car in the garage. 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. 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. The stepper motor is used to increase the value of II10 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) By the way, when changing the transmission ratio according to the i1i speed as in the above-mentioned conventional system, the rate of change of the transmission ratio with respect to the vehicle speed is constant, and therefore at a constant steering angle. If the change in the wheel steering angle with respect to the change in vehicle speed is S-, which is the same in the low and high vehicle speed ranges, when the wheels are turned during driving, the lateral acceleration that acts on the vehicle body or its behavior is determined by the turning point of the wheels. Even if the speed is constant, the vehicle becomes stiff at high speeds, so the behavior of the vehicle body becomes greater in the high speed range than in the low speed range. This causes deterioration of the ride comfort and driving operability of the vehicle when turning. Based on this, the rate of change of the transmission ratio with respect to vehicle speed is set to be large in the low vehicle speed range and small in the high vehicle speed range, so that the behavior of the vehicle body due to changes in vehicle speed is always approximately constant when turning with a constant steering angle. It is desirable to do so.

However, even with such settings, it is difficult to necessarily match the theoretical setting value with the actual rate of change in the transmission ratio during driving, and it is conceivable that the behavior of the vehicle body may vary slightly in response to changes in vehicle speed.

The present invention has been made in view of the above points, and its purpose is to appropriately correct the change rate characteristic of the transmission ratio with respect to the vehicle speed, thereby improving the speed of the vehicle when turning with a constant steering angle. The purpose of this invention is to ensure that the behavior of the vehicle body is always set consistently and accurately, to further improve the ride comfort and driving operability of the vehicle during turns, and to obtain more stable steering characteristics.

(Means for Solving the Problems) In order to achieve the above object, the solving means of the present invention provides a means for solving the problem by connecting the steering wheel to the steering wheel in the steering force transmission path 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 wheel steering angle. This variable transmission means is composed of, for example, an M star gear mechanism or a differential gear R mechanism, and an actuator such as a stepping motor that controls the operation of the centering mechanism. Further, a vehicle speed detection means for detecting the medium speed of the vehicle, and a controller for inputting an output signal from the vehicle speed detection means and outputting a control signal to the transmission variable means,
The present invention is configured to include a behavior state detection means for detecting the behavior state of the vehicle body when the automobile turns, and a correction means for correcting the transmission ratio control characteristic in the controller by inputting the detection signal of the behavior state detection means.

(Function) Therefore, in the present invention, with the above configuration, when the steering wheel is steered to turn the wheels, the controller operates and controls the transmission variable means, and the transmission ratio of the heavy wheel steering angle to the steering wheel steering angle is adjusted. It is variably controlled depending on the vehicle speed.

In that case, the behavior state of the vehicle body such as lateral acceleration and yaw rate that acts on the vehicle body when the vehicle turns is detected by the behavior state detection means, and the correction means that receives this detection signal is used to adjust the transmission ratio to the transmission variable means in the controller. The control characteristics are corrected in accordance with the actual vehicle behavior state, so that the behavior of the vehicle body as the vehicle speed changes at a constant steering angle is always kept constant and accurate. Therefore, the ride comfort and driving operability of the vehicle during turning are further improved, and more stable steering characteristics are achieved.

(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
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 variable transmission device that changes the transmission ratio R of the wheel steering angle θW to the steering wheel steering angle θH. Means 9 is 8UJ.

As shown in enlarged detail in FIGS. 2 to 4, the variable transmission 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 'T1 star gear mechanism 13 includes a sun gear 14 fixed to the input shaft 12 and a ring gear A fixed to the intermediate shaft 4.
715, for example, three planetary binions 16, 16, . ．． ... is the pinion shaft 17.17.・
... and a binion carrier 18 which is supported by the input shaft 121 and externally fitted rotatably to the input shaft 121. Also,
One sector gear is formed on the binion carrier 18, and a binion 21 fixed to the rotation lll1h20a of the stepping motor 20 is meshed with the sector gear 19. The planetary binion 16°1 is rotated around and supported on the kit rear 18.
G, . . . are transferred between the sun gear 14 and the ring gear 15, and this vinyl A 16.16. It 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 R15 and the intermediate shaft 4 through rotational transfer. .

On the other hand, 33 is a controller comprising a computer which outputs a control signal to the transmission variable means 9 to control the stepping 20. The controller 33 controls the steering angle θH of the steering wheel 1. a steering wheel angle sensor 30 that detects the vehicle's running speed V (vehicle speed), a vehicle speed sensor f31 as a vehicle speed detection means that detects the running speed V (vehicle speed) of the vehicle, and a lateral acceleration sensor that detects the lateral acceleration as the behavioral state of the vehicle body when the vehicle turns. Acceleration sensor 35 (
Each output signal from the behavioral state detection means) is input.

As shown in detail in FIG. 5, the controller 33 controls the steering wheel angle sensor 30 and the vehicle speed sensor 31.
The transmission variable means should control the steering wheel steering angle θH and vehicle speed V detected respectively by checking and comparing them with a characteristic map set in advance as shown in FIG. 7 and stored in the characteristic storage unit 34. A target transmission ratio calculation unit 37 that calculates the target transmission ratio R receives the output signals from the lateral acceleration sensor 35, compares the measured lateral acceleration with a preset vehicle behavior characteristic map, and deals with the difference. Corrected transmission ratio r
At the same time, the target transmission ratio R calculated by the iA calculating section 37 is reversely calculated using the corrected transmission ratio r so that the transmission ratio R becomes small when the lateral acceleration is large, as shown by the broken line in FIG. When the lateral acceleration is small, the transmission ratio R is corrected to be large, and the resulting transmission ratio R'
(=R+r) to the motor drive unit 38; and a correction unit 36 that supplies the motor drive unit 38 with a signal corresponding to
a motor drive section 3 that is driven by a pulse signal so that the actual rotation angle of the stepping motor 20 detected by the above matches the rotation angle corresponding to the calculated target transmission ratio R';
It consists of 8. As shown in the figure, the characteristic map read by the calculation unit 37 is based on the steering angle θ! (For example, the transmission ratio R of the wheel steering angle θW is set to be large at high vehicle speeds and small at low vehicle speeds, and
The rate of change is set to be large in low vehicle speed ranges and small in high vehicle speed ranges so that the behavior of the vehicle body is always constant regardless of vehicle speed.

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 S+, the actual vehicle speed V detected by the vehicle speed sensor 31 is read, and in step $2
Then, the calculation unit 37 calculates the steering wheel steering angle θ1 (45 and the vehicle speed V
is compared with the characteristic map shown by the solid line in FIG. 7, and the target transmission ratio R to be controlled by the transmission variable means 9 is calculated. next,
In step S3, the lateral acceleration applied to the vehicle body detected by the lateral acceleration sensor 35 is read, and in step $4, the read lateral acceleration is compared with a vehicle behavior characteristic map preset by the correction unit 36, and the difference is calculated. The corresponding corrected transmission ratio r (corresponding to the difference between the solid line and the broken line shown in FIG. 7) is calculated. Furthermore, in step S5, the target transmission ratio R calculated in step S2 is corrected by the corrected transmission ratio r calculated in step S4, and the transmission variable means 9 actually adjusts the target transmission ratio R to a new target transmission ratio R calculated by one inch. '=R+r
Calculate. After that, in step S6, the control amount (rotation angle) of the stepping motor 20 corresponding to the transmission ratio R' is calculated, and then the process proceeds to step S7. do.

Therefore, due to the above-mentioned υItItlBj property, the controller 33 is configured to correct the target transmission ratio R determined by the calculation section 37 in accordance with the lateral acceleration to the vehicle body when the vehicle turns. .

Therefore, in the above embodiment, while the car is running,
When the steering handle 1 is turned, the input shaft 1 is connected to the variable transmission means 9 via the handle shaft 2.
2, and the sun gear 14 of the planetary gear mechanism 13 rotates. Further, the steering wheel steering angle θF which changes with the steering of the steering wheel 1 is detected by the steering wheel steering angle sensor 3o, and the vehicle speed V at that time is detected by the vehicle speed sensor 31. A control signal is output from the controller 33 that receives the output signal to the stepping motor 20 of the variable transmission means 9, and the rotation of the motor 20 is controlled. As a result, the binion carrier 18 in the planetary gear mechanism 13 is rotationally driven. That is, in the variable transmission means 9, the sun gear 1
4 rotates by an angle proportional to the steering angle θH of the handle 1, and at the same time, the pinion rear 18 rotates] - roller 3
The motor 20 is rotated according to the rotation angle of the stepping motor 20 controlled by the motor 3. Therefore, the ring gear 15 of the variable transmission 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 θ11, and the rotation of the intermediate shaft 4 As a result, the middle 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 θt is variably controlled in accordance with the vehicle speed V.

In the case of motor vehicle, the lateral acceleration sensor 35 detects the lateral acceleration to the vehicle body when the vehicle turns, and the corrected transmission ratio r is calculated by the correction unit 36 of the controller 33 based on this detection signal. The transmission ratio R computed by the calculation unit 37 by
is corrected. Therefore, the behavior of the vehicle body as the vehicle speed changes at a constant steering wheel angle θ1 is always set to a constant level with good viscosity, thereby further improving the ride comfort and driving operability of the vehicle when turning. This results in more stable steering characteristics.

In the above embodiment, the lateral acceleration sensor 35 is used as a behavior state detection means for detecting the behavior state of the vehicle body.
The present invention is not limited to this, and it is also possible to detect, for example, 3-ray 1- and correct the controllability of the transmission ratio based on this.

(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 variable means, the vehicle body when turning at zero weight is provided. By detecting the behavior state of the vehicle and correcting the transmission ratio characteristics of the variable transmission means accordingly, the behavior of the vehicle body that accompanies changes in vehicle speed at a constant steering angle can always be set to be constant and accurate. As a result, more stable steering characteristics 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 variable transmission means, and FIGS.
5 is a block diagram showing the configuration of the controller, FIG. 6 is a flowchart showing the routine processed by the controller, and FIG. 7 is a sectional view of the controller's calculation section. It is a characteristic diagram of the map read in. DESCRIPTION OF SYMBOLS 1... Steering handle, 3... Steering gear device, 8... Wheels, 9... Variable transmission means, 1
3... Planetary gear mechanism, 20... Stepping motor, 30... Steering wheel steering angle sensor, 31... Vehicle speed sensor, 33... Controller, 35... Lateral acceleration sensor, 36... Correction Department. Patent applicant: Mazda Motor Corporation Agent 1) Hiroshi ζ-1
... 11 Figure 1] to Figure 2'' left lower lower position)

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 an output signal from the vehicle speed detecting means and outputting a control signal to the transmission ratio variable means; and a behavioral state detecting means for detecting a behavioral state of the vehicle body when the vehicle turns; A steering apparatus for an automobile, comprising: a correction means for correcting a transmission ratio control characteristic in the controller by inputting a detection signal of the behavior state detection means.