JPS6136061A - Rear-wheel steering apparatus for car - Google Patents

Abstract

PURPOSE:To smoothly change the posture of a chassis on turning by constituting the captioned apparatus so as to obtain the nonlinear characteristic in which the front-wheel steering angle with respect to the steering angle of a steering wheel increases within a small steering-angle range of the steering wheel and said steering angle reduces, over said range. CONSTITUTION:A front center lever 3 is turned by shifting a rack shaft 2a in the axial direction by the revolution of a steering wheel 1, and the right and left front wheels 5 are steered through a tie-rod 4 and a knuckle arm 5, the right and left rear wheels 14 are steered similarly by the movement of an input shaft 11 interlocked with the above-described lever 3. The front edge part of said lever 3 is axially supported by a shaft 9 onto the rear edge part of a front link 8 axially installed 7 onto a chassis side member 6, and a fitting member 31 fixed at the top edge of the side arm part 3a is fitted into an S-shaped cam groove 101 of a cam member 10 fixed onto the chassis side member 6. While, also a rear-wheel steering apparatus is equipped with a rear center lever 12, rear link 16, and a cam member 18.

Description

[Detailed description of the invention] Industrial use bone The present invention relates to a front and rear wheel steering device for an automobile.

Conventional Technology In automobiles equipped with a front and rear wheel steering system that steers both the front wheels and the rear wheels at the same time as the steering wheel is operated, the front wheels are generally not actually steered in terms of responsiveness of the vehicle body motion to steering when driving at high speeds. It is already known that it is better to apply slight in-phase steering to the rear wheels in proportion to the angle, while anti-phase steering of the front and rear wheels is better for improving the narrowing of the vehicle body at low speeds.

Therefore, we focused on the fact that the steering angle is small when driving at high speeds, and large steering is performed mainly when driving at low to medium speeds.In the small turning angle range near a straight line, the front and rear wheels are steered in phase.
In other steering angle ranges, a system has been developed in which the front and rear wheels are steered in opposite phases to satisfy the above-mentioned requirements, and is disclosed, for example, in Japanese Patent Application Laid-Open No. 163969/1983.

Problems to be Solved by the Invention As mentioned above, in a front and rear wheel steering system in which the front and rear wheels are steered in the same phase in a small turning angle range near a straight line, and in which the front and rear wheels are steered in reverse phase at a turning angle larger than the above, it is difficult to drive at high speed. However, when driving at medium or low speeds, for example, when the steering wheel is turned from 09, i.e., straight ahead, to a large turning groove to perform a turning motion, the turning radius r of the vehicle body will vary depending on the vehicle speed. If constant, the difference δ between the front wheel steering angle δF and the rear wheel steering angle δR
Since it is almost inversely proportional to F-δR, in a small turning angle range where the front and rear wheels are steered in the same phase, δF-61 is extremely small and the turning radius r is large, and the direction of the vehicle body relative to the steering angle of the steering wheel is extremely small. There is very little change in the so-called previous effect,
Furthermore, when the above-mentioned small steering angle range is exceeded and the front and rear wheels are in the reverse phase steering range, δd - δR increases rapidly, and the degree of decrease in the turning radius r becomes rapid. Eventually, the steering angle becomes smaller as shown by the dotted line in Fig. When the steering angle θ of the steering wheel is near the maximum steering angle position θ1 in the front and rear wheels in-phase steering range, the turning radius r, that is, δ7−δ
R suddenly changes unnaturally, and the centrifugal force due to the turning of the car body is δ
1−δ1 η7 j”r j2F T+ H Example 1
1-7-1- μ word P Juyo is the fifth word in Ton and Seiki.
As shown by the dotted line in the figure, the centrifugal force suddenly changes when the steering angle of the steering wheel approaches the maximum steering angle θ1 in the front and rear wheel in-phase steering range, as described above.

As mentioned above, if the turning radius and centrifugal force suddenly change during steering, it not only gives a great sense of discomfort to the driving operation, but also makes it difficult for the driver to predict changes in the vehicle body posture, which poses a major obstacle to the driving operation. .

The object of the present invention is to solve the problems of conventional devices, such as unnatural sudden changes in turning radius and centrifugal force during large steering turns, without impairing steering response during high-speed driving. be.

Means for Solving the Problems The present invention provides an automobile in which the front and rear wheels are steered in the same phase in a small steering angle range of the steering wheel, and the front and rear wheels are steered in reverse phase in a steering angle range exceeding the small steering angle. In front and rear wheel steering systems for automobiles, the front wheels are steered in such a way that the front wheel steering angle relative to the steering angle of the steering wheel is large in the small turning angle range of the steering wheel, and becomes small when it exceeds the small turning angle range of the steering wheel. Before configuring the device and changing the steering angle of the steering wheel.

It is characterized in that the steering angle difference between the rear wheels exhibits a substantially linear or nearly linear smooth change characteristic.

As a result of the above, the steering response during high-speed driving is extremely good, similar to that of conventional front and rear wheel steering devices, and when driving at medium or low speeds, the difference in steering angle between the front and rear wheels is linear or linear. The turning radius of the heavy object, which is almost inversely proportional to the front and rear wheel steering angle difference, changes very smoothly and naturally, completely eliminating any discomfort in driving, and the centrifugal force is also almost linear. Since the vehicle exhibits change characteristics, the vehicle body posture changes gently when turning, and driving operations can be simplified.

Embodiment Hereinafter, an embodiment of the present invention will be explained with reference to the accompanying drawings. In FIG. A pinion that rotates as the handle rotates 10 times, and a rack shaft 2α that moves in the axial direction due to the rotation of the pinion are installed inside,
By rotating the steering handle 1, the rack shaft moves in the axial direction via the pinion and rotates the front center lever 3, thereby causing the front wheel tie rod 4.4 and the knuckle arm which are pivotally attached to the front center lever 3 to move. 5(Z, 5α), the left and right front wheels 5, 5 are rotated by one king pin to perform steering.

The front center lever 3 is attached to the rear end of the front link 8 whose front end is pivoted to the vehicle body side member 6 by a shaft 7.
A fitting member 31 such as a bottle is attached to the distal end of the side arm 3α extending to one side from the shaft attachment portion of the TL front center lever 3 to the front link 8. The fitting member 31 fits into the cam groove 101 of the front wheel side cam member 10 fixed to the vehicle body side member 6, and extends rearward from the pivoting part of the front center lever 3 to the front link 8. The center end portions of the left and right tie rods 4, 4 are pivotally attached to the rear end portion of the arm portion 3b by shafts 4a, 4α.

In the above, when the steering handle 1 is turned to the left, for example, the rack shaft 2α moves to the left in the figure, and the front center lever 3 turns counterclockwise about the shaft 9.
Due to the 70 rotations, the tie rod shaft attachment part at the rear end of the rear arm 3b of the front center lever 3 is displaced to the right in the figure, and the front wheels 5, 5 are rotated to the left by the king pin 1 via the tie rods 4, 4. Then, the steering wheel is turned to left.

In this case, as the front center lever 3 rotates counterclockwise around the shaft 9, the side arm portion 3α rotates forward, and the fitting member 31 at the tip thereof is inserted into the cam groove 101 of the cam member 10. The cam groove 101 is bent in a substantially inverted S-shape with respect to the longitudinal direction of the vehicle body, so that a predetermined steering angle close to the neutral position as shown in the figure can be achieved. In this range, the fitting member 31 is guided by the cam groove 101 and is displaced to the right in the figure, and the center of rotation of the front center lever 3, that is, the shaft 9 is displaced to the right in the figure about the shaft 7.

Therefore, the tie rod shaft attachment portion at the rear end of the rear arm portion 3b of the front center lever 3 is connected to the shaft 9 of the front center lever 3.
The front center lever 3 is moved by the cam groove 101 of the cam member 10 by the rightward displacement due to the counterclockwise rotation around the center.
In other words, the center of rotation of the shaft 9 is displaced to the right by the value of 1 rightward displacement of the inner body, and the front wheel 5 is rotated to the left around the king pin. The actual steering angle of the front wheels is large.

As the steering wheel 1 is further turned to the left, the amount of rightward displacement of the center of rotation of the front center lever 3 by the cam groove 101, that is, the shaft 9, gradually decreases, and therefore The actual steering angle of the front wheels also gradually decreases, and near the maximum steering angle, the center of rotation of the front center lever 3, that is, the rightward displacement of the shaft 9, becomes zero, resulting in a non-linear situation as shown by the solid line F in Fig. 2. The steering angle ratio characteristics are as follows. This nonlinear characteristic of the steering angle ratio can be arbitrarily changed and set by changing the shape of the cam groove 101 of the cam member 10.

The rear wheel steering device is almost the same as the front wheel steering device described above, and includes a rear center lever 12, a rear link 16, and a rear wheel side cam member 1.
8.

That is, the rear center lever 1 is attached to the rear end of the rear link 16, the front end of which is pivotally connected to the vehicle body side member 6 through the shaft 15.
2 is rotatably supported, and a fitting member 121 such as a bottle is fixed to the tip of a side arm 12α extending to one side from the shaft 17 of the rear center lever 12. The fitting member 121 is fitted into the cam groove 181 of the rear wheel side cam member 18 fixed to the rear wheel side cam member 18, and the rear end portion of the rear arm portion 12b extending rearward from the pivot point of the shaft 17 of the rear center lever 12 is attached to the rear end portion of the rear arm portion 12b. The central end of the side tie rods 13, 13 is the shaft 13α,
13α, and the front end of the input shaft 11 is pivoted to the side arm 3α of the front center lever 3.The rear end of the input shaft 11 is pivoted to the side arm 12α of the rear center lever 12. It becomes.

As described above, for example, by rotating the steering wheel 1 to the left, the front center lever 3 is moved to the shaft 9.
When the rear center lever 12 rotates counterclockwise about the shaft 17, the rotation is transmitted to the rear center lever 12 by the input shaft 11, and the rear center lever 12 rotates counterclockwise about the shaft 17. The tie rod shaft attachment portion of the rear arm portion 12h of No. 12 is displaced to the right in the figure, and the tie rod 13,
13 moves to the right in the figure, and the rear wheel side knuckle arm 1
Since the direction of the knuckle arm 4α is opposite to that of the front wheel side knuckle arm 5α, the rear wheel 14 is attempted to be rotated to the right around the king pin, that is, in the opposite direction to the front wheel 5. However, the cam groove 181 of the rear wheel side cam member 18 is not aligned with the front wheel side cam member 10.
Since it is almost S-shaped, contrary to the cam groove 101,
In the predetermined steering angle range from the illustrated neutral position, the fitting member 12
1 is guided by cam #1181 and displaced to the left in the figure.The rotation center of the center lever 120, that is, the shaft 17 is rotationally displaced to the left in the figure around the shaft 15, and due to the shape of the cam groove 181, the shaft 17 By setting the leftward displacement amount A' of the rear arm portion 12b to be larger than the rightward rotational displacement amount A of the tie rod shaft attachment portion of the rear arm portion 12b about the shaft 17,
The tie rod shaft mounting portion is displaced to the left in the figure by A'-, A, and the rear wheels 14 rotate slightly in the same direction as the front wheels 5, resulting in in-phase steering of the front and rear wheels.

When the steering wheel 1 is further rotated to the left, the amount of leftward displacement A' of the shaft 17 at the cam groove 181 becomes small, and the tie rod shaft attachment portion of the rear arm 125 about the shaft 11 becomes small. The amount of rotational displacement A to the right becomes larger than the above A', and the tie rods 13, 13 move to the right, resulting in reverse phase steering for the front and rear wheels, with the rear wheels following the solid line in Figure 2. As shown in Figure R, in a small turning angle range, the front wheels are steered in the same phase to improve steering response when driving at high speeds, and in large turning angle ranges, the front and rear wheels are steered in opposite phase to improve steering response when driving at low speeds. It is possible to obtain rear wheel steering characteristics that can significantly improve small side steering characteristics.

In the above, in the conventional front and rear wheel steering device, the rear wheel steering characteristics are almost the same as those of the present invention shown by R in FIG. 2, but the front wheel steering characteristics are shown by the dotted line F' in FIG. Therefore, in the range below the maximum steering angle in the rear wheel in-phase steering range, the steering angle difference δA δR between the front wheel steering angle δF and the rear wheel steering angle δR is extremely small In addition, the increase rate of the difference in steering angle between the front and rear wheels after the maximum steering angle in the rear wheel in-phase steering area is large. The difference in steering angle between the front and rear wheels suddenly changes near the steering angle θ1, and the vehicle turning radius r, which is almost inversely proportional to the difference in steering angle between the front and rear wheels, is extremely unnatural near the steering angle θ1, as shown by the dotted line in Figure 4. If the steering wheel suddenly changes from 0° to large turn 1 during normal driving at medium or low speeds to perform a turning motion, the turning angle of the vehicle body relative to the steering wheel operating angle will be extremely unnatural and will cause problems in driving operation. Not only does it give a sense of discomfort, but the centrifugal force when the vehicle turns changes significantly around the steering wheel operating angle θ1, as shown by the dotted line in Figure 5, making it difficult for the driver to predict changes in the vehicle posture. The problem was that driving skills became extremely difficult.

In the present invention, the steering characteristics of the front wheels are shown in the small steering angle range, that is, the steering wheel operation angle θ is Oo
In the range from 01 to 01, the steering wheel operation angle θ
By setting the front wheel actual steering angle 6IP as a dog, and setting the nonlinear characteristic such that δF with respect to the above θ becomes small after θ1, the front wheel steering angle difference δIF in the front and rear wheel in-phase steering range is
-6R is larger than that of the conventional device, and as shown in Figure 3 α, the front and rear wheel steering angle difference δy with respect to the steering wheel operation angle θ is
-δR is constructed so that it exhibits smooth characteristics close to IJ near or linear in the entire steering range from the small steering angle to the maximum steering angle.

In the present invention, the front wheel steering mechanism and the rear wheel steering mechanism are not limited to the embodiment shown in the first figure, but the front wheel steering mechanism is such that the actual steering angle of the front wheels is large relative to the steering wheel operation angle in the in-phase steering range of the front and rear wheels. In the front and rear wheel in-phase steering range, any structure that achieves a nonlinear steering angle ratio in which the actual front wheel steering angle relative to the steering wheel operation angle gradually decreases can be adopted; Any configuration may be adopted that provides in-phase steering with the front wheels in the angle range and anti-phase steering with the front wheels in the turning angle range beyond the small turning angle range.

Effects of the Invention According to the present invention configured as described above, in an automobile equipped with a front and rear wheel steering device, the steering response during high speed driving is improved by performing in-phase steering of the front and rear wheels at a small steering angle i [. As shown in Figure 4 α, the vehicle body turning radius r changes smoothly with respect to the steering wheel operating angle during large steering turns while driving at medium to low speeds, which improves driving performance. In addition, the centrifugal force when the vehicle turns has an almost linear characteristic I: as shown in Figure 5, α, so the change in vehicle posture is gentle and there are no obstacles to driving operation. All of these issues have been resolved, and this will greatly contribute to the promotion of practical use of front and rear wheel steering devices.

[Brief explanation of drawings]

FIG. 1 is an explanatory plan view showing one embodiment of the present invention, FIG. 2 is a diagram showing the steering angle characteristics of the front and rear wheels with respect to the steering wheel operating angle, and FIG. 3 is a diagram showing the steering angle characteristics of the front and rear wheels with respect to the steering wheel operating angle. FIG. 4 is a diagram showing the characteristics of the turning radius of the vehicle body with respect to the steering wheel operation angle, and FIG. 5 is a diagram showing the characteristics of centrifugal force with respect to the steering wheel operation angle. 1...Steering handle, 3...Front safety pL/BA, 5...Front wheel, 8...Front link. DESCRIPTION OF SYMBOLS 10... Cam member, 11... Input shaft, 12... Rear sensor p/<-114... Rear wheel, 16... Rear link, 18... Cam member, 4, 13...・Tie rod. that's all

Claims (3)

[Claims] (1) In response to the steering operation of the front wheel steering device based on the left and right steering operation of the steering wheel, the front and rear wheels are steered in the same phase in the small turning angle range of the steering wheel, and when the small turning angle range is exceeded, the front and rear wheels are steered in the same phase. In a vehicle equipped with a rear wheel steering device that steers the rear wheels so as to achieve wheel reverse phase steering, the front wheel steering angle relative to the steering angle of the steering wheel is large in the small turning angle range of the steering wheel, and small in the small turning angle range of the steering wheel. The front wheel steering device is configured to exhibit nonlinear characteristics that become small when the steering angle range is exceeded, and the difference in front and rear wheel steering angles with respect to changes in the steering wheel turning operation angle is almost linear or has a smooth change characteristic that is close to linear. A front and rear wheel steering device for an automobile, characterized by having the following features. (2) The front wheel steering device has a side arm portion extending to one side and a rear arm portion extending rearward at the rear end portion of the front link whose front end portion is rotatably pivoted to the vehicle body side member. A front center lever, in which the center end of the front wheel tie rod is pivoted, is rotatably attached to the rear end of the rear arm, and the front center lever is rotated to the front link by rotating the steering handle. The front center lever is configured to rotate around the pivot point, and the fitting member provided on the side arm of the front center lever fits into the cam groove of the cam member fixed to the vehicle body side member, thereby rotating the front center lever. As the fitting member moves within the cam groove as the lever rotates around the pivot point on the front link, the pivot point of the front center lever on the front link moves to the vehicle body side member of the front link. The front and rear wheel steering device for an automobile according to claim 1, wherein the front and rear wheel steering device for an automobile is configured to be rotatably displaced from side to side about a pivot point. (3) The rear wheel steering device includes a side arm portion extending to one side and a rear arm portion extending rearward to the rear end portion of the rear link whose front end portion is rotatably pivoted to the vehicle body side member. A rear center lever having a center end of a rear wheel tie rod is rotatably pivoted to the rear end of the rear arm. It is configured to rotate around the pivot point to the rear link, and the fitting member provided on the side arm of the rear center lever fits into the cam groove of the cam member fixed to the vehicle body side member. However, as the fitting member moves within the cam groove as the rear center lever rotates around the pivot point on the rear link, the pivot point on the rear link of the rear center lever moves closer to the rear link's vehicle body. The front and rear wheel steering device for an automobile according to claim 1 or 2, wherein the front and rear wheel steering device for an automobile is configured to be rotatably displaced from side to side about an axis attachment point to a side member.