JPS61122075A - Steering apparatus for automobile - Google Patents

Abstract

PURPOSE:To carry out more closely the variable control of steering characteristic by changing the ratio of steering angle and turn steering angle of wheels in response to the magnitude of vehicle speed and steering angle. CONSTITUTION:A transmission ratio variable structure 10 which is coupled to a gear 8 through an intermediate shaft 9 is provided in a steering force transmitting passage between a steering wheel 3 and a steering gear 8. The gear 8 is constituted to have a variable gear ratio type which changes the gear ratio in response to steering angle. And the transmission ratio of the transmission ratio variable control structure 10 is controlled by a controller 26 on the basis of a vehicle speed signal from a vehicle speed sensor 27. Accordingly, it is possible to decrease the transmission ratio of turn steering angle to make the stability of running excellent in high speed running, and it is possible to increase the transmission ratio to improve the sharpness in low speed running.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a steering device for an automobile that changes the transmission ratio of a steering angle to wheels depending on the vehicle speed and the steering angle of a steering wheel.

(Prior art) An automobile steering device converts the rotation of a steering wheel into a lateral displacement of a tie rod through a steering gear device such as a rack-and-nion steering gear device, and moves the left and right wheels connected to both ends of the tie rod. However, in this case, the amount of rotation of the steering wheel (steering angle) and the turning angle of the wheels (steering angle) are usually always maintained in a constant correspondence relationship. However, for example, when driving at high speeds, it is desirable to reduce the ratio of the turning angle to the steering angle (transmission ratio) to ensure driving stability, and when driving at low speeds, it is desirable to increase the transmission ratio to make the vehicle's behavior more agile. It is desirable to provide a good driving feeling and to make it easier to park the vehicle in the garage.

Therefore, as disclosed in, for example, Japanese Unexamined Patent Publication No. 58-224852, a speed-sensitive steering device has been proposed in which the ratio of the turning angle to the steering angle is changed depending on the vehicle speed. As shown in Fig. 6, a transmission mechanism F consisting of a pair of variable pitch pulleys C1D and a V-belt E wound between both pulleys is interposed between the handle A and the steering column B. , the pitch diameter of the driven pulley D is controlled by a stepping motor G so that it increases as the vehicle speed increases. According to this, the rotational transmission ratio from the steering wheel A to the steering column B becomes smaller at high speeds, and as a result, the steering angle of the wheels for a given steering angle is small at high speeds and becomes large at low speeds, and the vehicle speed increases. Corresponding good steering characteristics can be obtained.

On the other hand, if the transmission ratio of the steering angle to the wheels is changed not only according to the vehicle speed as described above, but also according to the size of the steering angle, the steering angle of the wheels can be changed according to the driving speed of the vehicle. It is possible to control the vehicle more precisely and appropriately depending on the situation, and for example, it becomes easier to park the vehicle in a garage.

However, when attempting to change the transmission ratio according to the vehicle speed and steering angle in this way, the problem arises that the control device becomes extremely complex and the cost increases significantly.

(Object of the Invention) The present invention is intended to address the above-mentioned actual situation regarding steering devices for automobiles, and is to change the ratio of the steering angle of the wheels to the steering angle not only in accordance with the vehicle speed but also in accordance with the steering angle. It is an object of the present invention to realize a steering device in which the control is performed with a simple configuration, and thereby to perform variable control of the transmission ratio more appropriately and precisely without a significant increase in cost. purpose.

(Structure of the Invention) That is, the steering device for an automobile according to the present invention includes a variable transmission ratio mechanism in the steering force transmission path between the steering wheel and the steering gear device, and a vehicle speed detection means for detecting the vehicle speed. a controller that receives a signal from the vehicle speed detection means and outputs a control signal; and an actuator that receives a control signal from the controller and controls the operation of the variable transmission ratio mechanism, and the steering gear device The vehicle is characterized by being equipped with a variable gear ratio mechanism that changes the gear ratio depending on the steering angle. The variable transmission ratio mechanism is comprised of, for example, a planetary gear mechanism or a differential bevel gear mechanism, and is controlled by the actuator to change the ratio of the turning angle of the wheels to the steering angle in accordance with the vehicle speed. Further, the above-mentioned steering gear device is configured with, for example, a sector gear type or a rack and pinion type gear mechanism, but the pitch of the teeth in the sector gear or rack etc. is set to be an uneven pitch, so that the input (steering angle)
The ratio of the output (steering angle) to the steering angle changes depending on the magnitude of the steering angle.

(Effect of the invention) According to the above configuration, it is possible to appropriately change the ratio between the steering angle and the turning angle of the wheels according to the vehicle speed and the magnitude of the steering angle. This makes it possible to perform variable control of the steering characteristics of the vehicle more precisely. As a result, for example, when driving at high speeds or when the steering angle is small, the transmission ratio of the wheel turning angle to the steering angle is reduced in order to obtain good driving stability, and when driving at low speeds or when the steering angle is large, the transmission ratio of the wheel turning angle is reduced. In order to obtain a steering characteristic that corresponds to the vehicle speed and steering angle, for example, by increasing the above-mentioned ratio. In particular, according to the present invention, variable control of the transmission ratio according to the steering angle is performed by using a gear device equipped with a variable gear ratio mechanism as a steering gear device, so that control of the variable transmission ratio mechanism is performed according to the vehicle speed. This simplifies the control circuit, and as a result, it becomes possible to achieve precise steering characteristics as described above without a significant increase in cost.

(Example) Embodiments of the present invention will be described below based on the drawings.

As shown in FIG. 1, a steering device 1 is connected to left and right wheels 7° 7 via a steering handle 3 to which one end of a handle shaft 2 is fixed at the center, and a link mechanism 6 consisting of a pitman arm 4, tie rods 5, etc. A steering gear device 8 is connected to the steering gear device 8, and a steering force transmission path between the steering wheel 3 and the gear device 8 is provided via an intermediate shaft 9. A variable transmission ratio mechanism 10 connected to 8 is provided.

The steering gear system @8 is of a variable gear ratio type in which the gear ratio changes depending on the steering angle, and as shown in an enlarged view in FIG. A nut 11 is meshed with a number of balls (not shown), and a sector gear 12 is meshed with a rack 11a formed on the outer periphery of the nut 11.

This sector gear 12 is fixed to a sector shaft 13 connected to the pitman arm 4, and when the intermediate shaft 9 rotates and the nut 11 moves left and right in the drawing,
The sector gear 1 rotates integrally with the sector shaft 13 to swing the pitman arm 4.
2 is an unequal pitch gear, and in particular, in this embodiment, the pitch diameter a of the teeth at the center is larger than the pitch diameter a of the teeth at both sides, so that the gear changes as the amount of rotation of the intermediate shaft 9 increases. so that the ratio becomes smaller (sector gear 12
) is configured so that the amount of rotation is large.

On the other hand, as shown in FIGS. 3 to 5, the variable transmission ratio mechanism 10 includes an input shaft 14 disposed parallel to the handle shaft 2 and on the same line as the intermediate shaft 9, and an input shaft 14 and a handle shaft. 2, and a planetary gear mechanism 17 provided between the input shaft 14 and the intermediate shaft 9. The planetary gear mechanism 17 also includes a sun gear 18 fixed to the input shaft 14, a ring gear 19 fixed to the intermediate shaft 9, and a plurality of gears (in the illustrated example) arranged at equal intervals between the two gears 18 and 19. 3) planetary binions 2o...2o,
The binion 20 is rotatably fitted onto the input shaft 14.
. . 20 via binion shafts 21 . . . 21, respectively. A sector gear 23 is integrally provided on the carrier 22, and a pinion 25 fixed to the rotating shaft of a stepping motor 24 is meshed with the sector gear 23.

However, this steering device 1 is equipped with a controller 26 that controls the rotation of the stepping motor 24. This controller 26 includes a vehicle speed sensor 27
A vehicle speed signal C is input from the controller, and the rotation amount (including the rotation direction) of the stepping motor 24 is set based on this signal C, and this is output to the stepping motor 24 as a control signal d. .

Next, the operation of the above embodiment will be explained.

When the steering wheel 3 is rotated while the car is running,
The rotation is transmitted from the handle shaft 2 to the input shaft 14 via a pair of input gears 15 and 16 in the variable transmission ratio mechanism 10, and rotates the sun gear 18 in the planetary gear mechanism 17. At this time, the stepping motor 24 is sent from the controller 26 to which the signal C from the vehicle speed sensor 27 is input.
A control signal d is output to the motor 24, and the motor 24 is rotated according to the vehicle speed indicated by the signal C. Accordingly, the pinion carrier 22 in the variable transmission ratio mechanism 10 is rotated via the pinion 25 and the sector gear 23. be rotated. Therefore, in the variable transmission ratio mechanism 10, the sun gear 1
At the same time, the pinion carrier 22 is rotated by the stepping motor 2.
Therefore, the transmission ratio, the ring gear 19 or the intermediate shaft 9 in the variable mechanism 10 is rotated according to the amount of rotation of the pinion carrier 22 in proportion to the amount of steering of the handle 3. It will be rotated by the amount that is increased or decreased.

On the other hand, when the intermediate shaft 9 rotates as described above, in the steering gear device 8 shown in FIG.
moves in the left-right direction in the drawing, and the sector gear 12 and sector shaft 13 are rotated accordingly. Since the sector gear 12 and the sector shaft are made smaller, as the amount of movement of the nut 11 or the amount of rotation of the intermediate shaft 9 increases, the gear ratio becomes smaller. 13 becomes larger. And this sector axis 13
The wheels 7.7 are steered via the link mechanism 6 in accordance with the amount of zero rotation. However, in the variable transmission ratio mechanism 10, the amount of rotation of the stepping motor 24 or the nion carrier 22 is set according to the vehicle speed, and in the steering gear device 8, the amount of rotation of the intermediate shaft 9 is set according to the steering angle. Because it is configured so that the gear ratio changes,
The rotational transmission ratio between the handle shaft 2 and the sector shaft 13, in other words, the ratio of the turning angle of the wheels 7, 70 to the steering angle is changed according to the magnitude of the steering angle and the vehicle speed. As a result, by setting the rotation amount of the stepping motor 24 in accordance with the vehicle speed and appropriately setting each pitch diameter a, b of the sector gear 13 in the steering gear device 8 in advance, it is possible to maintain a constant steering angle, for example. The steering angle of the wheels relative to the steering angle is made small when driving at high speeds and large when driving at low speeds, and the ratio of the turning angle to the steering angle is made smaller when the steering angle is small and even larger when the steering angle is large. This makes it possible to achieve precise control according to the vehicle's performance, resulting in good running stability when driving at high speeds or when the steering angle is small, and good steering performance when driving at low speeds or when the steering angle is large. This makes it possible to control steering characteristics to make the steering more agile.

In this case, since control over the magnitude of the steering angle is performed by the steering gear device 8 having a variable gear ratio mechanism, control over the variable transmission ratio mechanism 10 only needs to be performed according to the vehicle speed, and therefore Although the transmission ratio is variable controlled depending on the angle, the controller 26 that controls the operation of the variable transmission ratio mechanism 10 only needs to have a simple configuration. This makes it possible to precisely control the steering angle without significantly increasing costs.

Note that in the above embodiment, the steering gear device 8
Although the steering gear device is constructed using a so-called pole-nut type variable gear ratio mechanism, a so-called rack-and-binion type variable gear ratio mechanism configured so that the pitch of the rack teeth changes may be used as the steering gear device.

[Brief explanation of drawings]

1 to 5 show an embodiment of the present invention, FIG. 1 is a perspective view showing the configuration of a steering device according to the embodiment, and FIG. 2 is a partially omitted side view showing the internal structure of the steering gear device. Figure 3 is a cross-sectional plan view showing the configuration of the variable transmission ratio mechanism and its associated control circuit, and Figure 4.5 is a sectional view taken along line N-IV and line ■-■ in Figure 3, respectively. be. 6th
The figure is a schematic configuration diagram showing a conventional example. 1... Steering ¥i! , 3... Steering handle, 8... Steering gear device, 10... Variable transmission ratio mechanism, 24... Actuator (stepping motor), 26... Controller, 27... Vehicle speed detection means (vehicle speed sensor).

Claims (1)

[Claims] (1) A variable transmission ratio mechanism provided in a steering force transmission path between the steering wheel and the steering gear device, a vehicle speed detection means for detecting vehicle speed, and a control signal obtained by inputting a signal from the vehicle speed detection means. A controller that outputs
and an actuator that controls the operation of the variable transmission ratio mechanism in response to an output signal from the controller, and the steering gear device includes a variable gear ratio mechanism that changes the gear ratio according to the steering angle. Automobile steering device.