JPH0429583B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a four-wheel steering device for a vehicle, that is, a device for steering the rear wheels in response to the steering of the front wheels by the steered wheels. The present invention relates to a four-wheel steering device that dynamically transmits information to a rear wheel steering device and mechanically controls the operation of the rear wheel steering device.

Conventionally, four-wheeled vehicles are typically steered by turning only the front wheels using steering wheels. However, problems have been pointed out in terms of maneuverability and steering, such as steering only the front wheels, which may cause the rear wheels to skid depending on the driving situation, or limit the turning radius, making it impossible to make small turns. In view of this, four-wheel steering devices that steer both the front wheels and the rear wheels have recently been researched and proposed.

In other words, in a four-wheel steering system, if the rear wheels are steered in the same direction as the front wheels when driving at relatively high speeds, lateral force is applied to the front and rear wheels at the same time, resulting in a phase lag from the steered wheels. This allows the vehicle to maintain its posture almost on the tangent to the turning circle, making it possible to smoothly change lanes when driving at high speeds, for example. Also,
If you steer the rear wheels in the opposite direction to the front wheels when driving at very low speeds, you can change the direction of the vehicle significantly, which can be a problem when you need to make wide turns in tight spaces, such as when parallel parking or parking in a garage. do not have.

Furthermore, considering that the front wheels are not steered significantly at relatively high speeds, and when the front wheels are steered significantly, it is when driving at relatively low speeds, the rear wheels are also turned in the range where the front wheels are steered small. A four-wheel steering system is required that steers the rear wheels in the same direction, and when the vehicle is steered significantly, steers the rear wheels in the opposite direction.

In principle, such four-wheel steering devices can be realized using various methods, but those that use many electrical or hydraulic means are relatively expensive and mechanically complex; There are also problems in terms of maintenance, safety in the event of failure, and reliability.

Therefore, in view of the above points, the present invention mainly controls the rear wheel steering device according to the operation of the front wheel steering device by mechanical means, and uses the power from the front wheel steering device to directly drive the rear wheels. It is an object of the present invention to provide a four-wheel steering device for a vehicle that has a simple structure and reliable operation for transmitting information to the device.

In order to achieve the above object, the present invention provides a rear wheel steering device that transmits force from a front wheel steering device to a rear wheel steering device and controls the operation of the rear wheel steering device in accordance with the operation of the front wheel steering device. A control device includes: an input shaft means connected to the front wheel steering device to move in a linear manner; and a first translation member engaged with the input shaft means so as to receive only a force in a first direction from the input shaft means; a second translational member engaged with the input shaft means so as to receive only a force in a second direction opposite to the first direction; disposed between the first and second translational members; 1st
urging means for urging the translational member in a second direction and the second translational member in the first direction with a predetermined set load; a force in the second direction from the first translational member; The first translational member is engaged with the first translational member so as to apply a force in a first direction to the first translational member, and the second translational member receives a force in the first direction from the second translational member. The linear moving member is engaged with the second linear moving member so as to apply a force in a second direction, is linearly moved by being transmitted with the force from the front wheel steering device, and is connected to the rear wheel steering device. an output shaft means for transmitting force to the input shaft means; and in a linear motion range corresponding to a range where the absolute value of the steering angle of the front wheels is smaller than a predetermined value, the force from the input shaft means is provided between the input and output shaft means; dead zone setting/amplification/inversion means for amplifying the force from the input shaft means and reversing the direction to apply the force to the output shaft means outside the linear motion range without transmitting the force to the output shaft means; There is.

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic plan view of a vehicle equipped with an embodiment of the present invention. In the figure, rotation of a steering shaft 2 caused by steering operation of a steering wheel 1 is converted into linear motion of a rack shaft 4 by a known rack and pinion mechanism 3. Both ends of the rack shaft 4 are connected to knuckle arms 6, 6 via side rods 5, 5, and the knuckle arms 6, 6 rotate the rack shaft 4 around the pivot shafts 6a, 6a.
The front wheels 7, 7 are steered by a known mechanism (not shown).

A pin 8 is embedded in the rack shaft 4 and engages with a forked portion 9a of an L-shaped link 9. L
A rod member 10, which is an input shaft means connected to a front wheel steering device constituted by a rack shaft 4 and the like and moves in a direct manner, is connected to the molded link 9 by a pin. The rod member 10 moves in the left-right direction in the figure, that is, in the front-rear direction of the vehicle, as the L-shaped link 9 swings. The rod member 10 has a cylinder portion 11 and a branch portion 12, and a first translation member 13, a second translation member 14, and a spring member 15 are housed in the cylinder portion 11. And through these, two flange parts 16, 17
An output shaft 18 having a diameter extends therefrom. First linear motion member 1
3 engages with the first shoulder portion 11a of the cylinder portion 11, and receives only the force from the rod member 10 in the first direction, rightward in the figure. The second translational member 14 engages with the second shoulder portion 11b of the cylinder portion 11, and receives only a force from the rod member 10 in the second direction, which is to the left in the figure. The spring member 15 is disposed between the first and second translational members 13 and 14, abuts against them, and biases them in the second direction and the first direction with a predetermined set load, respectively. The two flange portions 16 and 17 of the output shaft 18 are engaged with the first translation member 13 and the second translation member 14, respectively. As a result, the output shaft 18 receives a force in the second direction from the first translational member 13 while applying a force in the first direction to it, and receives a force in the first direction from the second translational member 14. While receiving a force, it also applies a force in a second direction. Since the predetermined set load is set to be larger than the force from the rod member 10, if no other force is applied to the output shaft 18, the horizontal movement of the rod member 10 will continue as it is.
shoulder portion 11b, second linear motion member 14, spring member 1
5, the first translational member 13, via the flange portion 16, or the first shoulder portion 11a, the first translational member 1
3. It is transmitted to the output shaft 18 via the spring member 15, the second direct-acting member 14, and the flange portion 17, and moves it in the same direction as the rod member 10.

On the other hand, another rod member 20 having a cylinder portion 19 is connected with a pin to the branch portion 12 of the rod member 10, and a piston rod 21 is inserted into this cylinder portion 19.
The piston portion 22 of is fitted. Therefore, when the piston portion 22 is in contact with either the left or right walls 19a, 19b of the cylinder portion 19, the horizontal movement of the rod member 20 is transmitted to the piston rod 21 and moves the piston rod 21 in the same direction. However, at a position between the positions where the piston rod 20 contacts the left and right walls 19a and 19b, the piston rod 2
No movement is transmitted to 1, so a dead zone is set. This position range where the front wheels 7 do not come into contact corresponds to a range where the absolute value of the steering angle of the front wheels 7 is equal to or less than a predetermined value.

The piston rod 21 is pin-coupled to a link 23 that is swingable about a pivot shaft 23a. The other end of the link 23 is a fork 23b, which engages with a pin 24 embedded in the output shaft 18. From the rod member 10, another rod member 20,
The force transmitted through the piston rod 21 is amplified by the link 23 so that this force is greater than the predetermined set load of the spring member 15 and its direction is reversed and transmitted to the output shaft 18. Therefore, the piston portion 2 of the piston rod 21
2 comes into contact with either of the left and right walls 19a, 19b of the cylinder portion 19, and when the reversed force is transmitted from the rod member 10 to the output shaft 18 through this path, the output shaft 18 is in the first linear motion state. The member 13 or the second linear member 14 is moved relative to each other within the cylinder portion 11 to compress the spring member 15 while moving in a direction opposite to the movement of the rod member 10.

A rack 25 is formed on the output shaft 18 and engages with a pinion 26. Figure 2 shows this part viewed from the side. The left and right movement of the output shaft 18 causes the pinion 26 to rotate, and another pinion 28 coupled to it by a shaft 27 also rotates. As a result, the rack shaft 30 engaged with the pinion 28 in the rack portion 29 is moved left and right (up and down in FIG. 1). In this way, in response to the left-right movement of the rack shaft 4 on the front wheel side, the rack shaft 30 on the rear wheel side also moves so that the piston portion 22 of the piston rod 21 is moved toward the wall 19 of the cylinder portion 19.
When it hits 9a or 19b, the direction is reversed and it moves linearly, and when it does not hit, it moves linearly in the same direction. The rack shaft 30 that is moved in this way is attached to the side rods 31 and 3 in the same way as the front wheel side.
1. The movement is transmitted to the rear wheels 33, 33 via the knuckle arms 32, 32, and steers them.

The operation of the embodiment having the above configuration will be explained using the graph of FIG.

Now, if we turn the steered wheels 1 to the right from the neutral position N where the steering angle is zero, the rack shaft 4 moves downward in Figure 1, that is, to the left, due to the action of the pinion rack mechanism 3, turning the front wheels 7, 7 to the right. (This steering angle is indicated by the θ _H axis).

At the same time, the L-shaped link 9 is rotated to the left to move the rod member 10 directly in the forward direction of the vehicle. The force due to this movement is applied to the second shoulder portion 11b of the cylinder portion 11, the second translational member 14, the spring member 15, and the first
The output shaft 1 is connected to the output shaft 1 via the linear motion member 13 and the flange portion 16.
8, and attempts to move it forward as well. At this time, the piston portion 22 of the piston rod 21 has not yet come into contact with the right wall 19b of the cylinder portion 19 in the range where the rightward steering angle of the front wheels 7, 7 is _less than the predetermined value θ1. The movement of the rod member 10 is only transmitted to the rod member 20 and not to the piston rod 21, and no force is transmitted from the link 23 side to the output shaft 18.
Therefore, the force transmitted from the piston rod 10 to the output shaft 18 via the spring member 15 and the like moves the output shaft 18 in the same direction as the rod member 10 without compressing the spring member 15. This direct motion of the output shaft 18 is transmitted to the rack shaft 30 via the pinions 26, 28, moving it to the left, and finally the front wheels 7,
The rear wheels 33, 33 are steered in the same direction as 7 (this steering angle is indicated by the θ _R axis).

However, when the rightward turning angle of the front wheels 7, 7 exceeds the predetermined value _θ1 , the piston portion 22 comes into contact with the right wall 19b of the cylinder portion 19, and the movement of the rod member 10 is reduced. The force is also transmitted to the piston rod 21 via the link 23, and is further transmitted to the output shaft 18 as an inverted force via the link 23.
Then, the spring member 15 is directed to the left via the second shoulder portion 11b and the second translational member 14, that is, the second
A force in the direction is applied, and a force in the right direction, that is, the first direction, is applied via the flange portion 16 of the output shaft 18 and the first translational member 13. Here, since the sum of these two forces is greater than the set load of the spring member 15, and the former of these two forces is smaller than the latter, the second translational member 14 is applied to the second shoulder 11b. Only the first translational member 13 moves away from the first shoulder portion 11a while remaining in contact and compresses the spring member 15. Therefore, while the rod member 10 moves forward, ie, to the left, the output shaft 18 begins to move rearward, ie, to the right, and the rear wheels 33, 33, which had been steered to the right, are now steered to the left. begins to be In this way, when the front wheels 7, 7 are further steered to the right, the rear wheels 33, 33 finally pass the neutral position and are steered to the left at the steering angle θ ₂ .

When turning the steering wheel 1 to the left from the neutral position,
This is the same as above except that the operation is reversed.

In this way, when the front wheels 7, 7 are within the predetermined steering angle range (range of θ ₁ or less left and right) between the neutral position N, the front wheels 7 and the rear wheels 33 are steered in the same direction. When it is out of range, the rear wheel 33 switches to the front wheel 7.
is steered in the opposite direction. As a result, the front and rear wheels 7, 33 are in a state of being steered to the same side with respect to the neutral position within a predetermined range (a range of θ ₂ or less in left and right directions) including and outside the predetermined steering angle range, Outside the range (more than θ ₂ left and right), the vehicle is steered to the opposite side of the neutral position.

As described above, according to the present invention, a mechanical control device comprising a biasing means such as a spring member, a link mechanism, etc. is used to transfer force from the front wheel steering device to the rear wheel steering device in a direct-acting manner. Since this is transmitted as steering force and drive controlled, there is no electrical means or hydraulic means, and complicated wiring and piping are unnecessary, making it mechanically simple and easy to maintain. will also be cheaper. Furthermore, since it is mechanically controlled, even if a failure should occur, the movement of the wheels is regulated to a certain extent, so it is superior in terms of safety and reliability.

[Brief explanation of drawings]

Fig. 1 is a schematic plan view of a vehicle equipped with an embodiment of the present invention, Fig. 2 is a side view of the rear wheel portion of Fig. 1, and Fig. 3 is a graph for explaining the operation. . [Explanation of symbols of main parts], Front wheel steering device...
1 to 8, Rear wheel steering device...25 to 33, Input shaft means...10 to 12, First linear motion member...13, Second
Direct-acting member...14, urging means...15, output shaft means...16-18, dead zone setting/amplification/inversion means...20-23.

Claims (1)

[Claims] 1. A steering device that steers the front wheels of a vehicle;
a rear wheel steering device that steers a rear wheel; and a rear wheel steering control device that transmits force from the steering device to the rear wheel steering device and controls the operation of the rear wheel steering device in accordance with the operation of the steering device. In a four-wheel steering device, the rear wheel steering control device includes an input shaft means that is connected to the steering device and moves in a linear manner, and receives only a force in a first direction from the input shaft means, and the rear wheel steering control device a first translational member that engages with the input shaft means; a second translational member that receives only a force in a second direction opposite to the first direction from the input shaft means and engages with the input shaft means; disposed between the first and second translational members,
urging means for urging the first translational member in a second direction and the second translational member in the first direction; receiving a force in a second direction from the first translational member; 1
The first translational member is engaged with the translational member so as to apply a force in a first direction to the translational member, and the second translational member receives a force in the first direction from the second translational member. Second
output shaft means that engages the second translational member so as to apply a force in the direction of the output shaft, receives the force from the steering device and moves in translation, and is connected to the rear wheel steering device to transmit the force; , is provided between the input shaft means and the output shaft means, and in a linear motion range corresponding to a range in which the absolute value of the steering angle of the front wheels is smaller than a predetermined value, the force from the input shaft means is applied to the output shaft means. In a range of steering angles where the absolute value of the steering angle of the front wheels exceeds the predetermined value, the force from the input shaft means is amplified, the direction is reversed, and the force is transmitted to the output shaft means. A four-wheel steering device for a vehicle, comprising: amplification/reversal means;