JPS6220755A - Steering device for car - Google Patents

Abstract

PURPOSE:To keep a steering handle at a constant position where a wheel steering angle is zero regardless of car and steering speed in turning and returning the steering handle, by controlling the transmission ratio characteristics of a wheel steering angle to a steering angle so as to be unchanged in both turning and returning the steering handle. CONSTITUTION:A variable means 9 for a transmission ratio is provided in way of a steering power transmission circuit, comprising planetary gears, differential gears and a step motor for the control thereof. And said means 9 is regulated by a controller 33 for the variable control of a transmission ratio of a wheel angle thetaW to a steering handle angle thetaH depending upon steering speed. Then, a transmission ratio at the time of steering is memorized and the transmission characteristics at the time of returning the steering handle is so controlled as to correspond to steering, according to a memorized signal. Consequently, gear ratio characteristics in steering agree to those in returning the steering handle, even if operating speed is different, thereby enabling the steering handle always to be kept at a constant position where a wheel steering angle is zero.

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 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 above transmission ratio is conversely reduced and the wheel rudder is adjusted to a constant steering angle in order to make the car'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 angle.

Therefore, in order to meet such requirements, conventionally, as disclosed in Japanese Patent Laid-Open No. 58-224852, the transmission ratio of the wheel steering angle to the steering wheel steering angle is changed according to the vehicle speed of the automobile. A speed-sensitive steering device has been proposed. This consists of a pair of variable pitch pulleys facing each other between the steering handle and the steering column.
In addition to providing a transmission mechanism consisting of bells 1 to 1, the pitch diameter of the driven pulley is controlled by a stepping motor so as to increase 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, for example, when a driver suddenly turns the steering wheel in an attempt to avoid an obstacle in front of the car while the car is running, the steering angle of the wheels may change significantly in response. In order to make this possible, it is conceivable to variably control the transmission ratio of the wheel steering angle to the steering wheel steering angle in accordance with not only the vehicle speed but also the steering speed of the steering wheel.

However, when the transmission ratio of the wheel steering angle to the steering wheel angle is variably controlled according to the vehicle speed and steering speed as described above, when the vehicle speed and steering speed change between turning and returning the steering wheel, the Since the operating amount of the stepping motor also changes, the transmission ratio when returning is different from when turning, making it impossible for the steering wheel to return to its original position accurately, resulting in an unstable steering wheel position where the steering angle of the wheels is zero. occurs.

The present invention has been made in view of the above points, and its purpose is to control the transmission ratio characteristic of the wheel steering angle to the above-mentioned steering wheel steering angle to be the same when turning the steering wheel and when turning the steering wheel back. By doing so, the steering wheel position at which the wheel steering angle becomes zero can always be kept constant even if the vehicle speed or steering speed changes between when the steering wheel is turned and when it is turned back.

(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 during the 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 for changing the transmission ratio of the wheel steering angle relative to the wheel steering angle is provided, and a controller is provided for controlling the operation of the transmission ratio variable means. The transmission ratio variable means includes, for example, a planetary gear groove or a differential gear mechanism, and an actuator such as a stepping motor that controls the operation of the gear mechanism. The controller is provided with a storage section that stores the transmission ratio of the transmission ratio variable means when the steering wheel is turned, and the controller determines the transmission ratio characteristics of the transmission ratio variable means when the steering wheel is returned based on the signal from the storage section. The control is configured to correspond to the same characteristics when turning the steering wheel.

(Function) Therefore, in the present invention, with the above configuration, the transmission ratio variable means is actuated and controlled by the controller while the automobile is running, and the transmission ratio of the wheel steering angle to the steering wheel steering angle is adjusted according to the steering speed of the steering wheel and the vehicle speed. variable control. Then, the transmission ratio of the transmission ratio variable means when the steering wheel is turned is stored in the storage section of the controller, and based on the stored data in this storage section, the transmission ratio characteristics when the steering wheel is returned are controlled so as to correspond to those when the steering wheel is turned. Ru. Therefore, even if the steering speed and vehicle speed when returning the steering wheel are different from those when turning the steering wheel, the gear ratio characteristics in both conditions are the same, and the steering wheel position at which the wheel steering angle becomes zero can always be kept constant. become.

(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 which a variable transmission ratio is provided in the middle of 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 are provided.

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.
and, 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. Also, a sector gear 19 is formed on the binion carrier 18, and the sector gear 19 has a rotating shaft 2 of a stepping motor 20.
Binion 21 fixed to 0a is engaged, and the rotation of stepping motor 20 moves the binion carrier 1
8 around the input shaft 12 to transfer the planetary binions 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 rotational speed from the handle shaft 2 or sun gear 14 to the ring gear 15 and the intermediate shaft 4 by increasing or decreasing the rotation of the steering wheel. has been done.

On the other hand, 33 is a controller comprising a computer that outputs a IIJiII signal to the transmission ratio variable means 9 to control the operation of the stepping motor 20.
A steering wheel angle sensor 30 that detects the steering wheel angle θH of
The output signal of is input. As shown in detail in FIG. 5, the controller 33 includes the steering wheel steering angle sensor 3.
a steering speed detection circuit 34 as a steering speed detection means for detecting the steering speed OH of the steering wheel 1 by time-differentiating the steering wheel steering angle θH detected by the steering angle θH at fixed time intervals, the detection circuit 34 and the steering angle sensor 30; The target transmission to be 1liiljllll is determined by the transmission ratio variable means 9 by inputting the respective output signals from the steering wheel 1 and comparing the steering speed (jH and steering angle θH of the steering wheel 1) with a characteristic map stored in advance in the characteristic storage section 35. a target transmission ratio calculation unit 37 that calculates the ratio R;
A transmission storage section 36 stores the target transmission ratio R1 calculated by the calculation section 37, that is, the transmission ratio of the transmission ratio variable means 9 when steering the steering wheel; 20, the actual rotation angle of the stepping motor 20 detected by a motor rotation angle sensor (not shown) is the target transmission ratio R calculated above.
and a motor drive unit 38 that is driven to match the rotation angle corresponding to the rotation angle. The characteristic map is set such that the transmission ratio R of the wheel steering angle θW to the steering wheel angle θH is constant with respect to the steering wheel angle θH and becomes smaller as the steering speed 6H becomes faster.

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 the first step S+, the steering wheel steering angle θH is read from the output signal of the steering wheel steering angle sensor 30, and in the next step S2, the steering angle change amount Δ of the steering wheel 1 is read.
Calculate θH. In this case, the above-mentioned steering wheel steering angle θH and steering angle change amount ΔθH are positive values when the steering wheel 1 is steered to the right (clockwise direction) and to the left (counterclockwise direction) as shown in FIG. 7, for example. When the vehicle is steered in a direction (around the clock), it is expressed as a negative value. After this arrogance, the process proceeds to step S3, where the shaped steering wheel steering angle θH and the steering angle change amount Δ
Based on the eight values of θH, it is determined whether the steering wheel 1 is turned to the "turning side" or "returning side". This determination is made by comparing the positive and negative signs of the steering angle change amount ΔθH with the positive and negative signs of the steering wheel steering angle θH, and if both are the same, it is determined to be the "r turn side", and if the opposite, it is determined to be the "return side". . To give a specific example, handle 1
is steered 90 degrees to the right and the steering angle θH is θ+-90'', and the amount of change in steering angle ΔθH is Δθ)4-45', the steering wheel is turned (more specifically, the steering angle is increased). If the result is θH-135°, and ΔθH--45', it is determined that the return steering has been performed and the value is θH-45°.

When the determination in step S3 is "turning side", the process proceeds to step S4, where the steering speed detection circuit 34
The steering speed OH calculated by is compared with the characteristic map in the characteristic storage section 35 to determine the target transmission ratio R (gear ratio) by calculation, and the target transmission ratio R is stored in the transmission storage section 36, and then In step S6, the motor 20 (actuator) is drive-controlled so that the transmission ratio of the transmission ratio variable means 9 becomes the target transmission ratio R.

On the other hand, when the determination in step S3 is "return side", the process proceeds to step S6, and a signal of a value corresponding to the steering wheel steering angle θH is sent from among the target transmission ratio R at the time of turning stored in the transmission storage unit 36. is outputted from the controller 33, and then, in step S6, the motor 2 is adjusted so that the transmission ratio of the transmission ratio variable means 9 becomes the target transmission ratio R at the time of turning off.
Controls 0.

Therefore, the controller 33 is configured to control the transmission ratio characteristic of the transmission ratio variable means 9 when the handle 1 is returned in correspondence with the time when the handle 1 is turned, based on the signal from the transmission storage section 36.

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 planetary gear mechanism 13 rotates. Further, the steering wheel steering angle θH that changes with the steering of the steering wheel 1 is detected by the steering wheel steering angle sensor 30, and the steering angle speed 11Ji (1>+ is detected by the steering speed detection circuit 34, and the steering speed is detected by the steering speed detection circuit 34. Detection circuit 3
A control signal is output from the controller 33 receiving the output signal of 4 to the stepping motor 20 of the transmission ratio variable means 9, and the motor 20 is controlled to rotate III.
The rotation of the pinion carrier 18 in the planetary gear mechanism 13 is driven to rotate via the pinion 21 and the sector gear 19. That is, in the transmission ratio variable means 9, the sun gear 14 rotates by an angle proportional to the steering angle θH of the handle 1, and at the same time, the binion carrier 18 rotates according to the rotation angle of the stepping motor 20 controlled by the controller 33. It will now be rotated. For this reason, the ring gear 15 of the transmission ratio variable means 9 and the intermediate shaft 4 integrated therewith are fixed to the binion carrier 1 with respect to the steering wheel steering angle θH.
The wheels 8.8 are rotated by an angle that increases or decreases the rotation angle of the intermediate shaft 4, and the wheels 8.8 are steered by this rotation of the intermediate shaft 4, thereby increasing the transmission ratio R of the wheel steering angle θW to the steering wheel steering angle θH.

is variably controlled.

In that case, the transmission ratio R is determined by the calculation unit 37 of the controller 33 to become smaller as the steering speed lJH of the steering wheel 1 increases. Wheel steering angle θ
W can be changed quickly, and the characteristics of the steering device can be made to appropriately match the driver's will, which is particularly effective when avoiding danger.

Further, when steering the steering wheel 1, it is determined whether the steering wheel 1 is turned or not, and when the steering wheel 1 is turned, the transmission ratio R calculated by the calculation section 37 of the controller 33 is stored in the transmission storage section 36, At the time of return, the transmission ratio variable means 9 is adjusted based on the stored transmission ratio R. Therefore, as shown in FIG. 8, even if the steering speed OH of the steering wheel 1 during turning and returning is different, the transmission ratio characteristic during returning is controlled to be the same as when turning. The position of the handle 1 where the angle θW is zero (θW=O) can always be kept constant.

Note that the above embodiment is applied to a steering device in which the transmission ratio R of the wheel steering angle θW to the steering wheel steering angle θH is variably controlled in accordance with the steering speed OH of the steering wheel 1, but the present invention Of course, the present invention can also be applied to a steering device in which the transmission ratio R is variably controlled in accordance with the vehicle speed of the automobile.

(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 ratio variable means, the transmission ratio is variable when the steering wheel is steered. By storing the transmission ratio of the means and making the transmission ratio characteristics when returning the steering wheel correspond to when turning the steering wheel, the steering wheel can be accurately returned to its original position after turning the steering wheel, and the wheel steering angle can be adjusted. The zero steering wheel position can always be kept constant, giving the driver a sense of security.

[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, FIG. 6 is a flowchart showing the routine processed by the controller, and FIG. FIG. 8, which is a diagram showing the concept for determining when to return, is an explanatory diagram of the transmission ratio characteristic calculated by 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, 30... Steering wheel steering angle sensor, 33... Controller, 34... Steering speed detection circuit, 36... Transmission storage section. Figure 1 Figure 2

Claims (1)

[Claims] (1) The transmission ratio of the wheel steering angle to the steering wheel steering angle is changed by a transmission ratio variable means provided in the steering force transmission path that transmits the steering force of the steering wheel to the wheels via the steering gear device. The steering device for an automobile is provided with a controller that controls the operation of the variable transmission ratio means, and the controller includes a storage unit that stores the transmission ratio of the variable transmission ratio unit during steering, and the controller includes a storage unit that stores the transmission ratio of the variable transmission ratio unit during steering. A steering device for an automobile, characterized in that the transmission ratio characteristic of the transmission ratio variable means when the steering wheel is returned is controlled in accordance with the signal when the steering wheel is turned.