JPH0116700Y2 - - Google Patents

Description

[Detailed description of the invention] (Field of industrial application) The present invention relates to a four-wheel steering system for a vehicle that steers the rear wheels in response to the steering of the front wheels. This invention relates to a structural improvement in which the characteristics are such that when the steering angle of the front wheels is small, they are in the same phase, and when it is large, they are in opposite phases.

(Prior Art) Conventionally, as a four-wheel steering system for such a vehicle,
As shown in Japanese Patent Application Laid-Open No. 55-91458, the steering ratio between the front wheels and the rear wheels is changed according to the steering angle of the steered wheels, and when the steering angle is small, the front wheels and the rear wheels are set in the same phase. In addition, when the steering angle is large, the phase is reversed to improve running stability at high vehicle speeds where the steering angle is small, and to improve turning ability at low vehicle speeds where the steering angle is large. something is proposed.

(Problem to be solved by the invention) However, in the above-mentioned conventional device, the structure for obtaining the above-mentioned rear wheel turning angle characteristics is such that the rod that cooperates with the steering of the front wheels adjusts the steering angle according to the turning angle of the front wheels. The sliding structure consists of a cam plate having a movable cam groove and a pin that is fixed to the rear wheel steering member that steers the rear wheels and is slidably held in the cam groove. The steering operation of the rear wheels tends to be unstable and the rear wheels cannot be steered smoothly, especially when the rear wheels change from the same phase to the opposite phase, and the steering feeling is jerky and smooth. It wasn't.

In view of this purpose, the purpose of the present invention is to provide the required rear wheel turning angle characteristics as described above (the turning angle of the rear wheels is in the same phase when the turning angle of the front wheels is small, and the turning angle of the rear wheels is in the same phase when the turning angle of the front wheels is large). The stroke (steering input) of the steering member of the steering device that steers the front wheels is mechanically distributed as a rotational motion, instead of the sliding structure between the guide groove and the pin. By adding up the movements of two members that move differently from each other when the rotational motion is transmitted, the steering operation of the rear wheels can be performed smoothly in conjunction with the steering of the front wheels, with a smooth steering feel. The purpose is to enable steering angle characteristics to be exhibited with good stability and operability.

(Means for Solving the Problems) In order to achieve the above object, the solving means of the present invention includes a steering device that steers the front wheels and a rear wheel steering device that steers the rear wheels. A rotation transmission rod that transmits the stroke of a steering member to a rear wheel steering device, and a rotation transmission rod that steers the rear wheels in the same phase within the set stroke value of the steering member of the steering device and in opposite phases when the stroke is equal to or greater than the set stroke value. an in-phase and anti-phase steering member that moves in a direction to steer the rear wheels in an opposite phase in accordance with a stroke of a steering member of the steering device; Directly transmits the steering input from the rotation transmission rod to either one as rotational motion,
The other is provided with a distribution mechanism that speeds up or decelerates the rotation and transmits the steering input as rotational motion. As a result, after the steering input is distributed as rotational motion to the two steering members by the distribution mechanism, the movements of both steering members are added together and transmitted to the steering member of the rear wheel steering device. Accordingly, when the steering angle of the front wheels is small, the steering angles of the rear wheels are set in the same phase, and when the steering angle of the front wheels is large, the steering angles of the rear wheels are set in opposite phases.

(Effect of the invention) Therefore, according to the four-wheel steering system for a vehicle of the present invention, the steering input is mechanically transferred to the in-phase and anti-phase steering members and the anti-phase steering member as rotational movements, respectively. By dividing and transmitting the signals and adding the movements of both steering members using a mechanical connection structure, the desired rear wheel steering angle characteristics, that is, the rear wheel steering angle can be made the same when the front wheel steering angle is small. Since the phase can be reversed when the front wheel steering angle is large, achieving the above-mentioned required rear wheel steering angle characteristics will result in a smooth steering operation of the rear wheels as the front wheels turn. It is possible to perform anti-phase operation with a smooth steering feel, and thus it is possible to easily achieve improvements in high-speed stability and small turning ability while maintaining good operational stability and operability, making it very useful in practice. be.

Furthermore, since the steering input transmitted to the two steering members is distributed as the same rotational motion, for example, by appropriately setting the gear ratio as represented by a spur gear, the two steering members can be It also has the advantage that it is easy to set the value of the rear wheel turning angle finally obtained by the operation of .

(Example) Hereinafter, an example as a specific example of the present invention will be described with reference to the drawings.

FIG. 1 shows a first embodiment of the invention. In the figure, reference numeral 1 denotes a steering device for steering left and right front wheels 2L, 2R;
includes a steering wheel 3 to be steered, a pinion 4a and a rack 4b that convert the steering force (steering input) of the steering wheel 3 into motion in the vehicle width direction and transmit the same, and a base end connected to each end of the rack 4b. left and right tie rods 5 as front wheel steering members;
5, and knuckle arms 6, 6 whose one end is connected to the tip of each tie rod 5, 5 and the other end is connected to the left and right front wheels 2L, 2R, respectively, and the steering 3
The left and right tie rods 5, 5 are moved in the vehicle width direction in response to the steering, thereby steering the left and right front wheels 2L, 2R left and right.

Reference numeral 7 denotes a rear wheel steering device for steering the left and right rear wheels 8L, 8R, and the rear wheel steering device 7 includes left and right knuckle arms 9, 9 whose one ends are connected to the left and right rear wheels 8L, 8R. , left and right tie rods 10, 10 as rear wheel steering members whose tips are connected to the other ends of the respective knuckle arms 9, 9, and a tie rod connecting rod 11 that connects the base ends of both tie rods 10, 10. It is equipped with

Further, the rear wheel steering device 7 has a pinion portion 12a at the front end that meshes with the rack 4b of the steering device 1, and converts the stroke of the front wheel steering member (tie rods 5, 5) into a rotational motion. The rotation transmission rod 12 extending in the longitudinal direction of the vehicle body transmits the information to the wheel steering device 7, and the rear wheels 8L, 8R are connected to the front wheels 2L, 2R within the set stroke of the steering member (tie rods 5, 5) of the steering device 1. The same-phase and opposite-phase steering member 13 moves in the direction of steering the front wheels 2L, 2R in the opposite phase when the stroke is equal to or greater than the set value. ，
5) An anti-phase steering member 14 that moves in a direction to steer the front wheels 2L, 2R in an anti-phase direction according to the stroke of step 5).
Then, the steering input from the rotation transmission rod 12 is increased in speed and transmitted as rotational motion to the in-phase and anti-phase steering member 13.
4, a distribution mechanism 15 that distributes the steering input as rotational motion so as to directly transmit the steering input as rotational motion; The addition mechanism 16 transmits information to the rudder members (tie rods 10, 10).

Specifically, the anti-phase steering member 14 includes a shaft portion 14a that is connected to the rear end of the rotation transmission rod 12 and extends in the longitudinal direction of the vehicle body and rotates in response to steering input, and a shaft portion 14a that is provided at the rear end of the shaft portion 14a. The rack and pinion mechanism includes a pinion portion 14b and a rack portion 14c extending in the vehicle width direction that meshes with the pinion portion 14b.The rack portion 14c is interposed in the middle of the tie rod connecting rod 11. Rear wheel steering member (tie rod 1)
0,10). On the other hand, the in-phase and anti-phase steering member 13 is constituted by a crank mechanism including a shaft portion 13a that extends in the longitudinal direction of the vehicle body and rotates, and a crank portion 13b provided on the shaft portion 13a. is connected to a holder member 17 as a casing of a rack and pinion mechanism that rotatably supports the anti-phase steering member 14, and the holder member 17 is connected to the rear wheel steering member ( tie rod 10,1
The adding mechanism 16 is configured to be displaced in the stroke direction of 0). The distribution mechanism 15 also has a large gear 15a fixed to the rear end of the rotation transmission rod 12, and a front end of the shaft 13a of the in-phase and anti-phase steering member 13, and meshes with the large gear 15a. It is constituted by a gear mechanism consisting of a small gear 15b.

Reference numeral 18 denotes a power cylinder interposed midway in the tie rod connecting rod 11, and the power cylinder 18 controls the stroke of the tie rod 10 by a control valve 19 also interposed midway in the tie rod connecting rod 11. Switching is controlled according to the direction, and the steering force of the rear wheels 8L and 8R is assisted to reduce the steering force and to downsize the rear wheel steering device 7. Further, the rear end of the rotation transmission rod 12 and the front end of the shaft portion 14a of the anti-phase steering member 14 are connected to two universal joints 2.
0, 21 and a telescopic joint 22 interposed between them
The holder member 17 can be smoothly displaced in the stroke direction of the tie rod 10. Others, 23 and 24
25 is a support portion that supports the holder member 17 slidably in the stroke direction of the rear wheel steering member (tie rods 10, 10), 25 is a support portion that rotatably supports the rear end of the transmission rod 12, and 26 and 2
Reference numeral 7 denotes a support portion that rotatably supports the front and rear ends of the shaft portion 13a of the in-phase and anti-phase steering member 13.

Next, to explain the operation of the first embodiment, when the steering wheel 3 is steered, the front wheels 2L, 2R are steered to the left or right by the front wheel steering members (tie rods 5, 5) depending on the steering angle. be done.
Further, the steering force (steering force) of the steering wheel 3 is transmitted to the distribution mechanism 1 via the rotation transmission rod 12.
5, the speed of the rotation is increased and transmitted to the in-phase and out-of-phase steering member 13 as a rotational motion, and as a result, the out-of-phase in-out phase steering member 13 uses its crank mechanism to direct the rear wheels 8L and 8R to the front wheels. The steering member (tie rods 5, 5) moves in the direction of steering in the same phase as the front wheels 2L, 2R within the stroke setting value, and in the opposite phase to the front wheels 2L, 2R when the stroke setting value is exceeded, The holder member 17 that rotatably supports the anti-phase steering member 14 is displaced in the stroke direction of the rear wheel steering member (tie rods 10, 10). At the same time, the rotation transmission rod 1
The steering force from 2 is transmitted by the distribution mechanism 15 directly to the anti-phase steering member 14 as a rotational movement, whereby the anti-phase steering member 14
The rear wheels 8L, 8R are moved in a direction in which they are steered in the opposite phase to the front wheels 2L, 2R in accordance with the stroke of the front wheel steering members (tie rods 5, 5). As a result, the rear wheel steering member (tie rods 10, 10) to which the rack portion 14c of the anti-phase steering member 14 is connected via the tie rod connecting rod 11 moves in a phase opposite to that of the same-phase anti-phase steering member 13. The movement of the steering member 14 is added and transmitted, and therefore the rear wheel 8
When the turning angle of the front wheels 2L, 2R corresponding to the steering angle of the steering wheel 3 is small, the turning angle of the front wheels 2L, 2R is in the same phase as the front wheels 2L, 2R.
When the steering angle of front wheel 2 is large, that steering angle is
It will be steered so that it is in the opposite phase to L and 2R.

Therefore, when the steering angles of the front wheels 2L, 2R are small, the steering angles of the rear wheels 8L, 8R are in the same phase, and when the steering angles of the front wheels 2L, 2R are large, the steering angles of the rear wheels 8L, 8R are set to the same phase. Since the rear wheel steering angle characteristic is such that the steering angles of the rear wheels are in opposite phases, it is possible to improve running stability in a high vehicle speed range and to improve turning ability in a low vehicle speed range.

Further, such rear wheel steering angle characteristics are obtained after the steering force from the rotation transmission rod 12 is distributed as a rotational motion by the distribution mechanism 15 as described above, and then the distributed steering force is transmitted to generate a motion. an in-phase and anti-phase steering member 13;
This is achieved by adding together the movements of the anti-phase steering member 14, which is moved by the same distributed steering force, using a mechanical connection structure, so that the distribution and transmission of the steering force and the associated movement are reliable and Since it is smooth, when steering, the rear wheels 8L and 8R can be smoothly brought into the same phase or opposite phase as the front wheels 2L and 2R are steered, and the steering feeling can be made smooth. Therefore, good operational stability and steering performance can be ensured, and the above-mentioned high-speed stability and
It is possible to further improve the maneuverability.

Furthermore, since the steering input transmitted to the two steering members 13 and 14 is distributed as the same rotational motion, the rear wheel turning angle is finally obtained by the operation of the two steering members 13 and 14. It becomes easy to set the value of 0 to an intended desired value. That is, as shown in FIG. 1, each gear 1 of the distribution mechanism 15 is typified by a spur gear.
By appropriately setting the gear ratios of 5a and 15b,
It becomes possible to easily specify the rotation ratio (acceleration or deceleration ratio) input to the two steering members 13 and 14. Conversely, by simply changing the rotation ratio (gear ratio), it is possible to relatively easily change the rear wheel steering angle to a desired value.

It should be noted that the present invention is not limited to the above-mentioned embodiments, but also includes various other modifications. For example, FIG. 2 shows a second embodiment (the same parts as in FIG. 1 are given the same reference numerals and their explanations are omitted), and the structure for transmitting the steering force to the rotation transmission rod 12' is as follows: The steering wheel 3' is extended further downward than the pinion part 4a provided at the tip thereof, and a bevel gear part 3'b is provided at the tip of the extension part 3'a.
A bevel gear portion 12'a that meshes with the rotation transmission rod 12' is provided at the front end of the rotation transmission rod 12', and the steering torque corresponding to the stroke of the steering member (tie rods 5, 5) of the steering device 1 is directly transferred to the rotation transmission rod 12. ′.
In this case as well, the same effects as in the first embodiment can be achieved.

Further, in the above embodiment, as the distribution mechanism 15,
Although the steering force is transmitted from the rotation transmission rod 12 to the same-phase and anti-phase steering member 13 as a rotational motion by increasing its rotation speed, the steering force is directly transmitted to the anti-phase steering member 14 as a rotational motion. Conversely, the steering force may be directly transmitted to the in-phase and anti-phase steering member 13 as a rotational motion, while the rotation of the steering force may be decelerated and transmitted to the anti-phase steering member 14 as a rotational motion; It is possible to achieve the following effects.

Furthermore, in the present invention, various other mechanical mechanisms can be adopted as the in-phase and opposite-phase steering member 13 and the opposite-phase steering member 14, and various other mechanical connection structures can also be adopted as the addition mechanism 16 accordingly. It is.

[Brief explanation of the drawing]

The drawings illustrate embodiments of the invention, and FIG.
FIG. 2 is a schematic perspective view showing the embodiment, and FIG. 2 is a partially enlarged vertical sectional view showing the second embodiment. 1...Steering device, 2L, 2R...Front wheels, 5...Tie rod (steering member for front wheels), 7...
...Rear wheel steering device, 8L, 8R...Rear wheel, 10...
Tie rod (rear wheel steering member), 12, 12'...
Rotation transmission rod, 13... Same phase and opposite phase steering member, 14... Opposite phase steering member, 15... Distribution mechanism, 15a... Large gear, 15b... Small gear.

Claims (1)

[Scope of utility model registration request] A four-wheel steering device for a vehicle comprising a steering device that steers the front wheels and a rear wheel steering device that steers the rear wheels, the rotation transmitting a stroke of a steering member of the steering device to the rear wheel steering device. a transmission rod; and an in-phase and anti-phase steering member that moves the rear wheels in the direction of steering the rear wheels in the same phase within a set stroke value of the steering member of the steering device and in the opposite phase when the stroke is equal to or greater than the set value; an anti-phase steering member that moves in a direction to steer the rear wheels in an anti-phase direction in accordance with the stroke of the steering member of the steering device; and a steering input from the rotation transmission rod to one of the two steering members. A distribution mechanism is provided that transmits the steering input directly to the two steering members as a rotational motion and speeds up or decelerates the rotation to the other and transmits the steering input as a rotational motion. A four-wheel steering device for a vehicle, characterized in that it is distributed as follows.