JPH0764274B2 - Rear axle steering device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automobile rear axle steering system, and more particularly to a rear axle steering system in which both sides are connected to a vehicle body by torque rods.

[Outline of Invention]

The torque rods connected to both sides of the rear axle are arranged so as to be inclined with respect to the front-back direction of the vehicle, and the lateral force that the wheels receive from the road surface during traveling is used to make the intersection points on the extension of the torque rods on both sides. The rear shaft is made to turn around the center of the vehicle, and this improves the stability of the vehicle when turning.

[Conventional technology]

For example, in a trunnion suspension type rear two-axle truck, as shown in FIG. 10, the rear front wheel 1 and the rear rear wheel 2 are connected to the vehicle body side by an intermediate torque rod 3 at the upper part, respectively, and the two axles are connected. Both sides of these axles 1 and 2 are connected to the vehicle body by means of left and right torque rods 4 and 5 at the lower portions of 1 and 2.

[Problems to be solved by the invention]

Torque rods 4, 5 connected to both ends of the axles 1, 2
Are arranged parallel to the front-back direction of the vehicle.
Therefore, the axles 1 and 2, the torque rods 3 to 5 and the vehicle body constitute a parallel link mechanism. Therefore, the torque rods 3 to 5 are rotated by the lateral force received by the wheels when the vehicle turns, as shown by the chain lines in FIG. 10, and the axles 1 and 2 maintain an angle perpendicular to the vehicle front-rear direction. While moving horizontally. That is, in the conventional two-axle trunnion suspension type rear axle, the rear axle is not steered during turning. Therefore, there is a drawback that the stability of the vehicle during turning is low.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a rear axle steering device in which a rear axle is rotated when a vehicle is turned by a lateral force received by a wheel from a road surface. It is what

[Means for solving problems]

According to the present invention, in a vehicle in which both sides of a rear shaft suspended by a suspension spring are connected to a vehicle body side via torque rods, the torque rods on both sides are arranged to be inclined with respect to the longitudinal direction of the vehicle. In this way, the intersection points on the extension of the torque rods on both sides are biased in the front-rear direction of the vehicle with respect to the rear axle to which these torque rods are connected, so that the rear wheels exert a lateral force when turning. When receiving, the rear axle receives a rotational moment equal to the product of the distance between the intersection and the rear axle and the lateral force, whereby the rear axle rotates about the above intersection. The present invention relates to a steering device.

In another invention, a hydraulic cylinder is connected to the torque rod, the hydraulic cylinder reverses steering before the rear axle is steered by the lateral force received by the rear wheels, and then the lateral steering is performed. The present invention relates to a rear-axle steering device that turns a rear-axle by a rotational moment caused by a directional force.

[Action]

Therefore, when the vehicle turns, the lateral force that the wheels receive from the road surface causes the rear axle to receive a rotational moment equal to the product of the distance and the lateral force between the intersection of the extension of the torque rods on both sides and the rear axle. It will be. Due to such a rotation moment, the rear shaft turns around the intersection of the extension of the torque rods on both sides, and the rear shaft is steered without using any special drive means.

By connecting the hydraulic cylinder for steering in the reverse direction to the torque rod prior to the steering of the rear axle by the lateral force, steering in the reverse direction is first performed by the hydraulic cylinder, and thereafter, the steering in the lateral direction is performed. The rear axle is swung in the positive direction by the rotational moment due to the force and steering is performed.

〔Example〕

FIGS. 3 and 4 show a truck equipped with a rear axle steering device according to an embodiment of the present invention. The truck is provided with a pair of left and right frames 10 that form the framework thereof. A cab 11 is supported on the front end side of the. The front end side of the frame 10 is supported by the front shaft 12, and the rear side thereof is supported by the rear front shaft 13 and the rear rear shaft 14. Here, the rear front shaft 13 constitutes a drive shaft, and the rear rear shaft 14 constitutes a driven shaft or a dead shaft.

Next, the structure of the suspensions of the rear two shafts 13 and 14 will be described. As shown in FIG. 5 and FIG.
A trunnion bracket 20 is fixed to each of the pair of left and right frames 10, and a trunnion shaft 21 is attached by these trunnion brackets 20 so as to be orthogonal to the frame 10. Spring seats 22 are rotatably attached to both ends of the trunnion shaft 21, respectively. Further, the spring seat 22 supports a leaf spring 23 constituting a suspension spring via a U bolt 24.

The rear front shaft 13 is suspended on the front end portion of the leaf spring 23 supported in this manner, and the rear rear shaft 14 is suspended on the rear end portion thereof. A torque rod 25 extending in the front-rear direction of the vehicle is connected to the central portion on the upper side of the rear front shaft 13 as shown in FIGS. 6 and 1. The tip of the torque rod 25 is connected to a cross member 28 that connects the left and right frames 10. On the other hand, both sides of the rear front shaft 13 and the rear rear shaft 14 are connected to the trunnion bracket via the torque rods 26 and 27 arranged on the lower side.
It is connected to 20. The lower torque rods 26 and 27 are arranged so as to be inclined with respect to the front-rear direction of the vehicle, as shown in FIG. 1, and the left and right torque rods 26 and 27 have extension lines. They intersect at points P and Q, respectively.

As described above, since the torque rods 26 and 27 on both sides of the rear two shafts 13 and 14 of the truck according to this embodiment are inclined, the lateral direction as shown by the arrow in FIG. When the wheels receive the force of, the axles 13 and 14 receive a rotational moment. In the future, the distance between the longitudinal middle point (the center of the left and right) of the front shaft 13 and the intersection point P will be r ₁ as shown in FIG. _1, and the lateral force and rotational moment received by the rear front wheel will be described.
When F ₁ and M ₁ are set, the rear front axis 13 is M ₁ =
It receives the rotational moment of F ₁ r ₁ . If the distance between the center point of the rear-rear shaft 14 in the longitudinal direction and the intersection point Q is r ₂ and the lateral force and rotational moment received by the rear-rear shaft are F ₂ and M ₂ , the rear-rear shaft 14 Receives a rotational moment of M ₂ = F ₂ r ₂ around the point Q. Due to such a rotation moment, the rear front shaft 13 and the rear rear shaft 14 respectively move to the left and right torque rods 2.
It makes a turning motion around the intersection of the extension lines of 6 and 27. That is, the rear front shaft 13 is rotated around the point P, and the rear rear shaft 14 is rotated around the point Q.

FIG. 2 is a graph showing the state of such rear axle steering in relation to the steering angle of the front wheels.
And, the rear rear shaft 14 is rotated so that the rear wheels steer from the turning center side. By such rear axle steering, it is possible to improve the stability of the vehicle when turning.

Next, a modified example of the above embodiment will be described with reference to FIGS. 7 and 8. According to the above-mentioned embodiment, since the rear shafts 13 and 14 are steered in the same direction as the front shaft, stability at the time of turning is improved, but maneuverability is not improved. In this modification, the torque rods 26 and 27 on both sides are connected to the vehicle body side via hydraulic cylinders 31 and 32, respectively.

Hydraulic cylinders 31 and 32 on both sides are hydraulic supply devices (not shown)
As shown in FIG. 8 by means of a hydraulic control device (not shown), the rear axle 1 is momentarily out of phase at the start of steering of the front wheels.
Steer 3 and 14. Therefore, when steering the front wheels,
The rear wheels are first steered in the opposite direction to the front wheels, and then the axles 13 and 14 are rotated so as to be steered in the same direction. Therefore, the gains of yawing and lateral acceleration are reduced to improve stability, and in addition, the hydraulic cylinders 31 and 32 perform antiphase steering with a fast response and a small steering angle, thereby increasing the yaw and lateral acceleration. Responsiveness is improved, and maneuverability during high-speed turning can also be improved.

Next, another modification will be described with reference to FIG. In this modified example, the two axles 13 and 14 on the rear side are connected to the vehicle body side via a pair of left and right torque rods 35 and 36, and the upper portions of the axles 13 and 14 are inclined. The torque rods 37 and 38 of the book are connected to the vehicle body side. The extension lines of the upper torque rods 37 and 38 intersect at a point P or a point Q.

Therefore, even with such a configuration, when the vehicle turns, the rear wheels are turned around the points P and Q by the lateral force, which improves the stability of the vehicle. Since the bushes of the lower left and right torque rods 35 and 36 are softer than the bushes of the upper two torque rods 37 and 38, the left and right strokes of the rear shafts 13 and 14 during turning The difference is the torque rod 35, 36
Will be absorbed by the soft bushes.

[Application example]

The present invention has been described above with reference to the illustrated embodiment, but the present invention is not limited to the above embodiment, and various modifications can be made based on the technical idea of the present invention. For example, the above embodiment relates to a rear two-axle truck, but the present invention is also applicable to a rear one-axle vehicle rear-axle steering system. It can also be applied to various types of vehicles other than trucks, for example, rear axle steering of buses and passenger cars. Further, instead of the hydraulic cylinders 31 and 32 shown in FIG. 7, an oil sump provided in the bushes of the torque rods 26 and 27 may be used to perform steering in the reverse direction of the rear shaft. Further, the oil supplied to these hydraulic cylinders 31, 32 may be taken out from the hydraulic pressure for power steering, the hydraulic pressure for the oil brake, and various other hydraulic pressure sources, instead of the dedicated hydraulic pressure source.

〔The invention's effect〕

As described above, according to the present invention, the torque rods on both sides are arranged so as to be inclined with respect to the front-rear direction of the vehicle, and the intersections on the extension of the torque rods on both sides are relative to the rear shaft to which these torque rods are connected. When the rear wheel receives a lateral force, it receives a rotational moment equal to the product of the distance between the intersection and the rear axle and the lateral force to center the intersection on the intersection. As a result, the rear shaft turns.

Therefore, when the front wheels are steered to turn the vehicle, the rear wheels are turned by the lateral force received by the rear wheels at this time, and therefore rear-axle steering is achieved without using a special drive source. It If the intersection point on the extension of the torque rod is arranged behind the connected rear axle, the rear axle will be steered to the turning center side, and the stability of the vehicle will be improved.

In another invention, the hydraulic cylinder is connected to the torque rod so that the steering in the reverse direction is performed prior to the steering of the rear axle by the lateral force received by the wheel. Therefore, such a hydraulic cylinder performs steering in the opposite direction prior to turning of the rear axle by the lateral force, and then performs steering in the forward direction by the rotational moment of the lateral force received by the rear wheels. Thus, such rear axle steering makes it possible to improve maneuverability during high-speed turning.

[Brief description of drawings]

FIG. 1 is a plan view of a main portion of a rear axle steering system according to an embodiment of the present invention, FIG. 2 is a graph showing a rear axle steering operation, and FIG.
FIG. 4 is a plan view of a truck equipped with a rear axle steering device, FIG. 4 is a side view of the same, FIG. 5 is an enlarged side view showing the arrangement of a torque rod, FIG. 6 is a front view of the same, and FIG. FIG. 8 is a main part plan view showing the rear axle steering device, FIG. 8 is a graph showing the operation of the rear axle steering device, FIG. 9 is a main part plan view showing another modified rear axle steering device, and FIG. It is a top view which shows arrangement | positioning of the torque rod of a rear biaxle. The names of the main parts in the drawings are as follows. 13 …… Rear front shaft 14 …… Rear rear shaft 23 …… Leaf springs 26, 27 …… Torque rod 31, 32 …… Hydraulic cylinder

Claims (2)

[Claims] 1. A vehicle in which both sides of a rear shaft suspended by a suspension spring are connected to a vehicle body side via torque rods, and the torque rods on both sides are arranged so as to be inclined with respect to the longitudinal direction of the vehicle. However, the intersection points on the extension of the torque rods on both sides are set so as to be biased in the front-rear direction of the vehicle with respect to the rear axles to which these torque rods are connected. A rear-axle steering apparatus, wherein the rear-axle steering device receives a rotational moment equal to a product of a distance between the rear-axle and a lateral force and rotates the rear-axle around the intersection. 2. A hydraulic cylinder is connected to the torque rod, and reverse steering is performed by the hydraulic cylinder prior to steering of the rear axle by the lateral force. Rear axle steering device according to the item.