JP2910160B2 - Automatic rear wheel steering mechanism for vehicles - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an automatic rear wheel steering mechanism for a rear two-axle vehicle.

[Prior Art] In a normal four-wheeled vehicle, the turning center is located near the intersection of a straight line perpendicular to the direction of the front wheels steered by a steering wheel during turning and two straight lines perpendicular to the directions of the rear wheels fixed in the straight traveling direction. Can be turned smoothly.

However, in the case of a rear two-axle vehicle, if all the directions of the rear wheels are fixed in the straight traveling direction, there are a plurality of intersections of a straight line perpendicular to the front wheel direction and a straight line perpendicular to each rear wheel direction, If the interval between the intersections is large, the deviation between the contact point of the rear wheel and the direction of the rear wheel accompanying the turning traveling of the vehicle becomes large, and the vehicle turns while skidding. For this reason, in a vehicle in which the distance between the rear axles is short, there is a problem in that the amount of sideslip of the rear wheels accompanying the cornering becomes excessive, and the wear of the rear wheels (tires) becomes remarkable.

In order to eliminate the side slip of the rear wheel, it is preferable to steer the rear wheel in accordance with the direction of the front wheel, but providing a steering mechanism linked to the steering wheel on the rear wheel causes an increase in weight and a significant increase in cost. Not so good.

Therefore, the rear wheels of the other rear axles can be steered while leaving one of the plurality of rear axles, so that the intersection of the steering axis (king pin) of the rear wheels with the ground is located slightly ahead of the ground contact point of the rear wheels. With this configuration, even if a special rear-wheel steering mechanism is not provided for the rear wheels, if the force that forces side slip is applied to the rear wheels during turning of the vehicle, the intersection of the rear-wheel steering axis with the ground and the rear wheels will be in contact. The lateral load acting on the ground contact point of the rear wheels acts as a moment about the steering axis of the rear wheels due to the deviation in the front-rear direction from the point (the trail amount), and the rear wheels are automatically steered in a direction that does not cause sideslip. As a result, a smooth turning travel without side slip on the rear wheels can be obtained.

However, in the case of a vehicle having the above-described automatic rear-wheel steering mechanism (self-steering mechanism), when the vehicle tries to move backward, the ground contact point of the rear wheel with respect to the intersection of the steering axis of the rear-wheel is on the side of the rear wheel traveling direction. And the moment about the steering axis of the rear wheel due to the lateral load acting on the rear wheel becomes unstable, and even if the direction of the rear transfer slightly deviates from the straight running direction of the vehicle, the deviation increases. As a result, there is a problem that in the worst case, the vehicle cannot go backward. For this reason, the automatic rear wheel steering mechanism disclosed in Japanese Patent Application Laid-Open No. 60-50072 is provided with a lock mechanism for fixing the direction of the rear wheels to the straight traveling position when the transmission is shifted to the reverse gear.

However, in a vehicle having the above-described automatic rear wheel steering mechanism,
Since the automatic rear wheel steering function is locked when moving backward, not only the effect of eliminating the side slip of the wheels is reduced, but also because the turning trajectory of the vehicle is different between when moving forward and when moving backward even with the same operation amount of the steering wheel, it is narrow When the forward and backward movements are repeated in a garage or the like, the position of the vehicle gradually shifts to the side, and it becomes difficult to return the vehicle to the original position.

[Problems to be Solved by the Invention] In view of the above-described problems, an object of the present invention is to eliminate the difference in turning trajectory between forward and reverse travels and eliminate lateral displacement of the vehicle due to repeated forward and reverse travel. It is to provide a rear wheel steering mechanism.

Means for Solving the Problems In order to achieve the above object, in the configuration of the present invention, in a rear two-axle vehicle having a driving wheel and a driven wheel, a rotating body is provided at both ends of a rear axle case coaxially with the rear axle case. An actuator that rotatably supports the driven wheel, supports a knuckle that supports each driven wheel by a kingpin on the rotating body, and rotates the rotating body to change the front and rear inclination of the kingpin according to the traveling direction of the vehicle. Is provided on the vehicle body side.

[Operation] When the transmission is shifted to the forward gear, the rotating body is rotated with respect to the rear axle case by the actuator, and the kingpin is tilted rearward. When a lateral load is applied that causes
The direction of the rear wheel is automatically steered around the kingpin, and a smooth turning travel without side slip on the rear wheel is obtained.
When the transmission is shifted to the reverse gear, the rotary body is rotated in the reverse direction by the actuator, and the kingpin is tilted forward, so that the automatic rear wheel steering action also works when the vehicle reverses, as in the case of forward running.

[Embodiment of the Invention] FIG. 6 is a rear view of a rear wheel equipped with an automatic rear wheel steering mechanism according to the present invention.
It is a top view of an axle vehicle. Knuckle 23 supporting front wheel 21
Are supported at both ends of a front axle case 34 by vertical king pins 22. The front axle case 34 is supported on the vehicle body by a known suspension spring. When the steering shaft 25 is rotated to the right by the handle, for example, the arm of the output shaft 27 of the steering gear mechanism 26 is swung, and the right nut 23 is rotated clockwise about the king pin 22 via the drag link 28. , Thai rod
The left and right front wheels 21 connected by 24 are deflected to the right.

The rear axle 32 of the front and rear wheels 33 is supported by the rear axle case 31.
The rotation of the propulsion shaft 29 driven by the engine is transmitted to the rear shaft 32 via the differential device 30. The rear axle 12 of the rear rear wheel 18 is supported by a rotating body 3 by a vertical king pin 20, and the rotating body 3 is rotatably supported by both ends of a rear axle case 13.
The king pin 20 is tilted back and forth by the rotation of the rotating body 3 with respect to the rear axle case 13. The rotating body 3 is rotated by an actuator 40 connected between the vehicle body (preferably, the rear axle case 13) and the rotating body 3. In FIG. 6, for ease of understanding, the king pins 22, 20 are shown at positions offset from the center in the width direction of the wheel.

FIG. 1 is a rear sectional view of an automatic rear wheel steering mechanism of a vehicle according to the present invention, FIG. 2 is an exploded perspective view of the same, and FIG. 3 is a side view of essential parts of the same. The present invention relates to a tilt of a kingpin for supporting a knuckle of a rear wheel corresponding to a forward / reverse movement of a rear shaft except one of a plurality of rear shafts (preferably, a rear shaft for supporting a driven rear wheel). By adjusting the angle (caster angle),
This is to eliminate the side slip of the rear wheel accompanying the cornering. Therefore, the rotating body 3 is rotatably supported at both ends of the rear axle case 13 that supports the other rear shaft except one rear shaft. Specifically, shaft portions 13a are formed at both ends of the cylindrical rear axle case 13, and the shaft portions 13a are fitted into the shaft holes 6 of the rotating body 3 so as to be relatively rotatable, and are not detached. The nut 5 is fastened to the end of 13a. However, the rotating body 3 may be directly fitted to the end of the rear axle 13 so as to be rotatable.

A pair of arms 4 extending radially outward are formed integrally with the rotating body 3, and pin holes 4 a coaxially arranged in each arm 4 are formed. Rear wheel 18
A knuckle 2 having a U-shape integral with a rear shaft 12 for supporting the upper and lower arms is superposed on the ends of a pair of upper and lower arms 4, and is swingably supported on the rotating body 3 by a king pin 20. Accordingly, the rear wheel 18 (FIG. 6) supported on the rear shaft 12 can be steered about the kingpin 20.

In order to regulate the inclination of the king pin 20 before and after, the abutting piece 8 is axially projected from the rotating body 3 into a notch 9a on the peripheral edge of the flange 9 connected to the end of the rear axle case 13, and A lever 10 is connected to the end of the lever 8. As shown in FIG. 3, the lever 10 is switched inside the notch 9a between a state in which the lever is tilted rearward and a state in which it is tilted forward in accordance with the forward / reverse travel of the vehicle.

As shown in FIG. 4, an actuator 40 is connected between the lever 10 and the vehicle body 17 (preferably, the rear axle case 13) to rotate the rotating body 3 via the lever 10. The actuator 40 has a cylinder 35 connected to the vehicle body 17 by a pin 19, and a rod 37 protruding outside from a piston 36 fitted to the cylinder 35 is connected to the lever 10 by a pin 38.

Next, the operation of the automatic rear wheel steering mechanism of the vehicle according to the present invention will be described. In FIG. 4, when the vehicle moves forward, the piston 36 of the actuator 40 is pushed rearward (to the right in FIG. 4) by pneumatic or hydraulic pressure, the rotating body 3 is rotated clockwise, and the kingpin 20 is tilted backward. Can be Therefore, the intersection a of the king pin 20 with the road surface 39 is ahead of the ground point b of the rear wheel 18 with the road surface 39 by the trail amount s (the fourth position).
(Left side in the figure).

In the forward turning operation of the vehicle, the lateral load (force for forcing the rear wheel to slide sideways) acting on the contact point b of the rear wheel 18 causes the king pin 20 to be applied to the rear wheel 18 due to the inclination angle (caster angle) α of the king pin 20. Acts as the center moment, so the rear wheel
18 is automatically steered around the kingpin 20 and the rear wheels
The direction of 18 changes to a direction that does not cause sideslip with respect to the turning locus of the vehicle.

On the other hand, when the vehicle moves backward, the piston 36 of the actuator 40
Is pushed forward, and the king pin 20 is tilted forward. The force for forcing the rear wheel 18 to skid rotates the rear wheel 18 about the kingpin 20, so that the rear transfer 18 does not automatically cause a skid, and the rear wheel 18 has no skid. Turning performance is obtained.

FIG. 5 is a rear sectional view showing a modified embodiment of the automatic rear wheel steering mechanism according to the present invention. Both end shaft portions 13 of rear axle case 13
A cylindrical rotating body 3 is rotatably supported by a, and the knuckle 2 is supported by the rotating body 3 by a kingpin 20 so as to be steerable. A protruding piece 3a projecting radially outward from the left and right rotating bodies 3 is a shaft 16
The worm gear 42 meshes with the partial gear 41 formed on the outer peripheral wall of the left rotating body 3. When the worm gear 42 is rotated forward and backward by an electric motor (not shown) as an actuator supported on the rear axle case 13, the front and rear inclinations of the left and right king pins 20 are changed.

[Effects of the Invention] As described above, the present invention has a rear wheel having a driving wheel and a driven wheel.
In an axle vehicle, a rotating body is supported at both ends of a rear axle case so as to be rotatable coaxially with the rear axle case, and a knuckle supporting each driven wheel is supported by the rotating body with a kingpin, and the rotating body is rotated. The vehicle body is provided with an actuator for changing the front and rear inclination of the kingpin in accordance with the traveling direction of the vehicle. Therefore, when the front wheels are steered during the traveling of the vehicle, regardless of whether the vehicle is traveling forward or backward, the vehicle is driven along with the traveling. When a lateral load that causes a side slip on the rear wheel is applied, the direction of the rear wheel automatically changes around the kingpin, so that a smooth turning travel without a side slip on the rear wheel can be obtained.

The rotating body supported by the rear axle case is rotated by an actuator in accordance with the traveling direction of the vehicle, and the front and rear inclinations of the kingpin that supports the rear wheel knuckle are switched, so the configuration is very simple. Yes, and can be provided at low cost.

By switching the front and rear inclinations of the kingpin that supports the knuckle of the rear wheel when the vehicle is moving forward and backward, there is no difference in the turning trajectory between the forward and backward traveling, and the lateral displacement of the vehicle due to repeated forward and backward traveling is eliminated. .

Since the actuator for rotating the rotating body can be disposed on the rear axle case, it can be applied to any suspension type rear two-axle vehicle.

[Brief description of the drawings]

FIG. 1 is a rear sectional view of an automatic rear wheel steering mechanism according to the present invention,
FIG. 2 is an exploded perspective view of the same, FIG. 3 is a side view showing a relationship between a flange of a rear axle case and a lever, FIG. 4 is a side view of an automatic rear wheel steering mechanism, and FIG. FIG. 6 is a rear sectional view of the automatic rear wheel steering mechanism according to the embodiment, and FIG. 6 is a plan view showing a schematic configuration of a rear two-axis vehicle provided with the automatic rear wheel steering mechanism according to the present invention. 2: nutshell, 3: rotating body, 12: rear axle, 13: rear axle case, 1
8: Goyo, 20: Kingpin, 40: Actuator

Continuation of the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) B62D 7/18 B62D 7/14

Claims (1)

(57) [Claims] In a rear two-axle vehicle having a driving wheel and a driven wheel, a rotating body is supported at both ends of a rear axle case so as to be rotatable coaxially with the rear axle case, and a nut supporting each driven wheel is a kingpin. An automatic rear wheel of the vehicle, wherein the actuator is supported on the rotating body, and an actuator that rotates the rotating body to change the front and rear inclination of the king pin in accordance with the traveling direction of the vehicle is provided on the vehicle body side. Steering mechanism.