JP2002087314A - Steering structure for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide favorable operation feeling without increasing assembling man-hours of a steering device. SOLUTION: A rack end 9 is provided on each end part of a steering rack 8 in a gear case 7, and a tie rod 10 is connected through it to the rack 8 to be slidable in a perpendicular direction to the axis. A knuckle 14 is connected to the rack 8 by the rod 10, and a relatively rotatable joint part is provided on a connection part of the rod 10 to the knuckle 14. A line connecting the joint part to a rotation center of a wheel is roughly parallel to a vehicle forward/rearward direction to make a parallel system. Between the gear case 7 in a rack boot 15 provided at an opening end part of the gear case 7 and the rack end 9, a spring 21 of which resiliency is strengthened on the inner wheel side as the steering device 1 makes steering from a neutral condition to energize the steering device 1 in such a direction as to restore to the neutral condition is provided. The spring 21 is formed to have length of about 1/2-1/3 of the stroke between the gear case 7 and the rack end 9 from the neutral condition to full steering.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steering structure for a vehicle, and more particularly to a structure of a rack-and-pinion type steering mechanism mounted on a four-wheeled vehicle.

[0002]

2. Description of the Related Art As a general automobile steering apparatus, for example, there is a rack and pinion type steering mechanism as shown in FIGS. In this steering device 51, a steering gear case 52 is disposed along the width direction of the vehicle body, and the steering gear case 52
Inside, a steering rack 53 is slidably provided. A substantially cylindrical rack end 54 is provided at each of the left and right ends of the steering rack 53, and the tie rod 55 is fitted with a ball joint 55 a provided at one end thereof into the rack end 54. The steering rack 53 is slidably connected in the direction perpendicular to the axis. A knuckle 56 described later rotatably supports left and right wheels (front tires) 57 and 58 on the vehicle body, and is connected to the steering rack 53 by tie rods 55. Further, rack boots 59 that cover the left and right open ends of the steering gear case 52 are provided, and both ends of the rack boots 59 are provided with wires 60 and clamps 61.
With this, it is fixed to the steering gear case 52 and the tie rod 55. The steering gear case 52 is mounted on the vehicle body by fitting a mount bracket (not shown) to portions A and B in FIGS. 6 and 7 and tightening them with bolts and nuts. In FIG. 6, reference numeral 62 denotes a steering pinion disposed along the vertical direction.

[0003] By the way, an automobile steering device 51
In order to obtain a linear steering characteristic, as shown in FIG. 8, it is desirable from the viewpoint of design that the steering mechanism be such that the inner wheel turning angle δ1 is larger than the outer wheel turning angle δ2 and the Ackerman type steering theory is obtained. According to the Ackerman-type steering theory, there is an advantage that the sideslip of the wheels 57 and 58 during the turning of the vehicle is extremely small, the wheels 57 and 58 can be turned smoothly, and the wear of the wheels 57 and 58 is also reduced. In a general specification car, the inner wheel turning angle δ1
And the outer ring turning angle δ2 is about 10 °.

However, according to the standard, as shown in FIG.
Narrow light vehicles (FF vehicles, FR vehicles), etc.
3. Since a space in the width direction is provided for the auxiliary equipment, the inner wheels 57 are used to avoid interference with the wheel house 64.
Is limited. On the other hand,
To reduce the minimum turning radius of the vehicle, the front wheels 57, 5
It is necessary to increase the cutting angle of 8 (total of the left and right cutting angles). Therefore, the outer ring turning angle δ2 may be designed to be increased (that is, it is difficult to increase the inner ring turning angle δ1 due to space limitations. Enlarge). In an ideal Ackerman steering, Figure 1
0, the rotation center C of the front tires 57, 58
And the extension of the operating point (joint portion between the tie rod 55 and the knuckle 56) O is designed to intersect at an intermediate point (see FIG. 9) on the axle 67 between the rear tires 65 and 66,
It is difficult to increase the turning angle δ2 of the outer ring 58, as is apparent from the neutral state of FIG. One of the methods to increase the turning angle δ2 of the outer ring 58
As an example, a parallel steering shown in FIG. 11 has been proposed. In this steering structure, a line connecting the rotation center C of the front tires 57 and 58 and the operating point O is disposed so as to be substantially parallel to the vehicle front-rear direction.
As is clear from the neutral state in FIG. 7A and the full steer state in FIG.
7 and the outer ring 58 have the same cutting angle, and the cutting angle of the outer ring 58 can be increased.

[0005]

However, in such a conventional parallel steering structure, especially at the time of low speed running at a vehicle speed of 5 to 10 km / h, such as at an intersection or a garage, as shown by a thin solid line in FIG. Since the steering characteristic is such that the steering torque decreases in the vicinity, the steering characteristic becomes unfavorable in terms of feeling. Here, the reason why the steering torque decreases is that at the time of low speed turning full steering,
Since the wheels (front tires) 57 and 58 have slip angles, if the full steer angle is large, a force such as a cornering force is generated on the wheels 57 and 58, and the moment by the wheels 57 and 58 becomes a notch torque, and the difference in the cut angle is reduced. There was no effective countermeasure by the link mechanism other than attaching.

The present invention has been made in view of the above circumstances, and has as its object to provide a vehicle steering structure capable of obtaining a good operability feeling without increasing the number of assembling steps of a steering device. Is to provide.

[0007]

In order to solve the problems of the prior art, according to the present invention, a steering gear case of a steering device is arranged in a width direction of a vehicle body, and a steering rack is slid in the steering gear case. The steering rack is provided movably and rack ends are provided at both ends of the steering rack, and a tie rod is slidably connected to the steering rack via the rack end in a direction perpendicular to the axis, so that the left and right wheels can rotate on the vehicle body. While the knuckle to be supported and the steering rack are connected by the tie rods, rack boots are provided at both open ends of the steering gear case to cover them, and a relatively rotatable joint is provided at the connection between the tie rods and the knuckle. Provided, a line connecting the joint portion and the rotation center of the wheel extends in the vehicle longitudinal direction. The steering structure for a vehicle which is arranged in parallel steering to be substantially parallel to,
In a rack boot provided at both open end portions of the steering gear case, the elastic force is located between the steering gear case and the rack end and serves as an inner wheel as the steering device turns steering from a neutral state. And an elastic body for urging the steering device in a direction in which the steering device returns to the neutral state is provided, and the elastic body is substantially １ ／ to 1 of a stroke between the steering gear case and the rack end from the neutral state to full steering.
/ 3 length.

In the present invention, the elastic body is a spring, a lip for holding the spring is provided on a rack boot mounting portion of the steering gear case, and an end of the spring on the steering gear case side is formed by the spring. The rack boot is integrally fixed to the end of the steering gear case. Further, in the present invention, an extension extending in the axial direction is provided at an end of the steering gear case, and an end of the spring is press-fitted and fixed to an inner peripheral surface of the extension.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on illustrated embodiments.

FIGS. 1 to 4 show a first embodiment of a vehicle steering structure according to the present invention. In the figure,
Reference numeral 1 denotes a steering device for controlling the direction of a front tire 2 of a four-wheeled vehicle. The steering device 1 of the present embodiment is configured as a rack and pinion type steering mechanism. This steering device 1
As shown in FIG. 1, a steering column 3 supported in a state of being stood obliquely upward toward the rear of the vehicle, a steering shaft 4 inserted and held in the steering column 3, The steering wheel 5 includes a steering wheel 5 attached to the upper end of the shaft 4, a steering pinion 6 attached to the lower end of the steering shaft 4, and a steering gear case 7 connected to the lower end of the steering pinion 6. The steering motion of the front tire 2 is converted.

As shown in FIGS. 2 and 3, the steering gear case 7 is disposed along the width direction of the vehicle body. I do. 2 and 3 show only one side of the steering gear case 7 because the opposite side has the same structure. Inside the steering gear case 7, a lower end portion of a steering pinion 6 extending along the up-down direction, and a steering rack 8 extending along the vehicle width direction and slidably provided are arranged.
A lower end of the steering pinion 6 is rotatably connected to a steering gear case 7 and is supported in a state of being engaged with the steering rack 8.

At the left and right ends of the steering rack 8, a substantially cylindrical rack end 9 having a large-diameter storage portion 9a is provided by screw fixing.
The tie rod 10 is connected slidably in the direction perpendicular to the axis of the steering rack 8 by fitting a ball joint 10 a provided at one end of the tie rod 10 into the storage portion 9 a of the rack end 9. A tie rod end 12 is fastened and fixed to the other end of the tie rod 10 by a nut 11, and the tie rod end 12 is provided with a ball stud 13. The other ends of the tie rods 10 are attached to left and right knuckles 14 by ball studs 13 of a tie rod end 12 or the like. The knuckle 14 is an arm that rotatably supports the left and right front tires 2 on the vehicle body.
And a tie rod end 13 to be connected to the steering rack 8. Moreover, in the steering device 1 of the present embodiment, a parallel steering system in which a line connecting the joint portion of the tie rod 13 and the knuckle 14 and the rotation center (king pin axis) of the front tire 2 is substantially parallel to the vehicle longitudinal direction. The steering wheels are provided so that the turning angles of the inner wheel and the outer wheel in the steering direction are always substantially the same.

On the other hand, at the left and right opening ends of the steering gear case 7, elastic bellows-like rack boots 15 are provided to cover the opening. A ring-shaped spring holding lip 16 is provided on one end mounting portion of the rack boot 15 located on the steering gear case 7 side, and a tip end of the lip 16 is attached to a rubber bush for a mounting bracket to a vehicle body (shown in the figure). One end of the rack boot 15 is fixed to the outer peripheral surface of the steering gear case 7 by externally fitting and overlapping the fitting portion 17 (not shown) and stopping from outside using a wire 18.
In addition, a spring pressing piece 16a that engages with a spring described later extends radially from the inner peripheral surface of the base end of the lip 16. And the other end of the rack boot 15
The tie rod 10 is fixed to the outer peripheral surface of the tie rod 10 by a clamp 19. Note that a steering rack bush 20 is disposed between the inner peripheral surface of the opening end of the steering gear case 7 and the outer peripheral surface of the steering rack 8.

Further, at the position inside the rack boot 15 and between the steering gear case 7 and the rack end 9, the steering device 1 shifts from the neutral state shown in FIG. 2 to the full steer state shown in FIG. A compression coil spring (elastic body) 21 is provided to increase the elastic force on the side of the front tire 2 serving as the inner wheel as the steering wheel is turned, and to urge the steering device 1 in a direction to return to the neutral state. . This coil spring 2
Reference numeral 1 denotes an outer peripheral surface of the steering rack 8, which is disposed along the axial direction, and is approximately 1/2 to 1/3 of a full-steer side of a rack stroke between the steering gear case 7 and the rack end 9 from a neutral state to a full steer. The length is formed. The end of the coil spring 21 on the steering gear case side is held and fixed to the opening end of the steering gear case 7 integrally with the rack boot 15 by the spring pressing piece 16 a of the lip 16.

In the steering structure according to the first embodiment of the present invention, the steering device 1 is located inside the rack boot 15 and between the steering gear case 7 and the rack end 9, and turns the steering from the neutral state. , The elastic force on the inner wheel side of the front tire 2 is strengthened, and the rack stroke is urged in a direction in which the steering device 1 returns to the neutral state.
Since the compression coil spring 21 having a length is provided, as the front tire 2 is steered, as shown in FIG.
From a certain steering angle, the rack end 9 becomes the coil spring 2
1 will be compressed. The reaction force of the coil spring 21 acts in a direction to return the rack end 9 to the original position (neutral state), so that the steering torque increases, especially at a low speed at a vehicle speed of 5 to 10 km / h such as at an intersection or a garage. This eliminates the sense of discomfort in the steering torque and provides a good steering feeling.

Here, good steering feeling means the relationship between the steering angle and the steering torque.
In this case, the steering torque increases almost linearly as indicated by a thick solid line, which is a desirable target value.
The steering torque is a force for rotating the steering wheel, and desirably increases as the steering angle increases, but gradually so as not to become too heavy. However, in order to reduce the minimum turning radius,
If a parallel steering device is used in which the steering angles of the inner wheel and the outer wheel in the steering direction of the front tire 2 are always substantially the same, if the structure is used as it is, the curve becomes as shown by a thin solid line in FIG. That is, at a steering angle of 0 to approximately 370 ° (0 to 1/2 stroke), the steering torque increases almost linearly, but thereafter, reaches a peak at a steering angle of approximately 490 ° (2/3 stroke), The steer torque curve gradually decreases.

In the steering structure of the present embodiment, since the coil spring 21 is compressed by the rack end 9, as shown by thick solid lines and broken lines in FIG.
It can be seen that the steer torque decreasing from around the half stroke can be corrected to the initial substantially linear steer torque. A thick solid line represents a steer torque curve of the coil spring 21 having a half stroke length, and a broken line represents a one-third stroke.
6 shows a steering torque curve of the coil spring 21 having a stroke length. Further, in the steering structure of the present embodiment, since the lip 16 having the spring pressing piece 16a is provided at one end of the rack boot 15, the end of the coil spring 21 on the steering gear case side is attached to the steering gear case 7 by the rack boot 15. Rack and pinion type steering device 1 which can be fixed integrally
This does not impair the assemblability of the device and the increase in the number of working steps due to the installation of the coil spring 21 can be reduced. It should be noted that the steer torque correction amount can be adjusted by changing the length of the coil spring 21 or changing the setting of the spring constant.

FIG. 5 shows a second embodiment of the vehicle steering structure according to the present invention. The steering structure of the second embodiment is different from that of the first embodiment in that an extension 7a extending in the axial direction is provided at the open end of the steering gear case 7, and a coil is provided on the inner peripheral surface of the extension 7a. The point is that the end of the spring 21 is press-fitted and fixed by interference fit. For this reason, the coil spring 2
The outer diameter of 1 is formed larger than the inner diameter of the steering gear case 7. Other configurations and operations are the same as those in the first embodiment. In the steering structure according to the second embodiment of the present invention, since the end of the coil spring 21 is fixed to the steering gear case 7 by the extension 7a of the steering gear case 7, the structure is further simplified. Other effects are the same as those of the first embodiment.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications and changes are possible based on the technical concept of the present invention. is there. For example, although the compression coil spring 21 is used as the elastic body, an elastic member such as a leaf spring, a rubber bush, or a bellows-shaped spring may be used instead.

[0020]

As described above, in the vehicle steering structure according to the present invention, the steering gear case of the steering device is disposed in the width direction of the vehicle body, and the steering rack is slidably provided in the steering gear case. With rack ends at both ends of the rack,
A tie rod is slidably connected to the steering rack in a direction perpendicular to the axis via the rack end, and a knuckle for rotatably supporting left and right wheels to a vehicle body is connected to the steering rack by the tie rod, while the steering wheel is connected to the steering rack. A rack boot covering both ends of the gear case is provided, and a relatively rotatable joint portion is provided at a connection portion between the tie rod and the knuckle, and a line connecting the joint portion and the rotation center of the wheel is formed in the front and rear of the vehicle. The steering gear case is disposed between the steering gear case and the rack end in a rack boot provided at both open ends of the steering gear case, As the steering device turns the steering from the neutral state, the elastic force on the inner wheel side becomes Mari, and the steering device provided with a resilient member for biasing in a direction to return to the neutral state, stands for stroke of said steering gear case of the elastic body from the neutral state to Furusutea and the rack end 1 /
Since it is formed to have a length of 2/3, the following effects can be obtained. That is, according to the vehicle steering structure of the present invention, even in a parallel type steering device in which the steering angles of the inner wheel and the outer wheel in the steering direction are always substantially the same, the neutral state is established as the steering is turned due to the presence of the elastic body. The biasing force increases in the returning direction, so that a substantially linear steering torque can be obtained, especially during low-speed running, and a good operability feeling can be maintained without increasing the number of assembling steps of the steering device.

[Brief description of the drawings]

FIG. 1 is a perspective view conceptually showing a steering device to which a vehicle steering structure according to a first embodiment of the present invention is applied.

FIG. 2 is a sectional view showing the steering gear case in which the steering device according to the first embodiment of the present invention is in a neutral state.

FIG. 3 is a cross-sectional view showing the steering gear case when the steering device according to the first embodiment of the present invention is in a full steer state.

FIG. 4 is a diagram showing a relationship between a steering angle and a steering torque.

FIG. 5 is a sectional view showing a steering gear case of a steering device according to a second embodiment of the present invention in a state where rack boots are omitted.

FIG. 6 is a sectional view showing one end side of a steering gear case of a conventional steering device.

FIG. 7 is a cross-sectional view showing the other end of a steering gear case of a conventional steering device.

FIG. 8 is a conceptual diagram showing an Ackerman type steering mechanism.

FIG. 9 is a conceptual diagram showing that a maximum turning angle of a front tire is limited in a light vehicle having a narrow vehicle width.

FIG. 10 shows an Ackerman type steering mechanism.
This is for explaining the turning angle of the front tire, and (a)
FIG. 2 is a conceptual diagram in which the steering device is in a neutral state, and FIG. 2B is a conceptual diagram in which the steering device is in a full steer state.

11 (a) and 11 (b) are views for explaining a turning angle of a front tire in a parallel steering mechanism, wherein (a) is a conceptual diagram in which a steering device is in a neutral state, and (b) is a conceptual diagram in which the steering device is in a full steering state. is there.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Steering device 2 Front tire 7 Steering gear case 7a Extension 8 Steering rack 9 Rack end 10 Tie rod 14 Knuckle 15 Rack boot 16 Ring holding lip 16a Spring holding piece 21 Compression coil spring (elastic body)

Claims (3)

[Claims] A steering gear case of a steering device is disposed in a width direction of a vehicle body, a steering rack is slidably provided in the steering gear case, and rack ends are provided at both ends of the steering rack.
A tie rod is slidably connected to the steering rack in a direction perpendicular to the axis via the rack end, and a knuckle for rotatably supporting left and right wheels to a vehicle body is connected to the steering rack by the tie rod, while the steering wheel is connected to the steering rack. A rack boot covering both ends of the gear case is provided, and a relatively rotatable joint portion is provided at a connection portion between the tie rod and the knuckle, and a line connecting the joint portion and the rotation center of the wheel is formed in the front and rear of the vehicle. In a vehicle steering structure arranged in a parallel type steering that is substantially parallel to a direction, in a rack boot provided at both open ends of the steering gear case, the steering gear case is located between the steering gear case and the rack end. As the steering device turns the steering from the neutral state, An elastic body is provided which urges the steering device in the direction in which the elastic force of the steering device is increased and the steering device returns to the neutral state, and the elastic body is substantially equivalent to a stroke between the steering gear case and the rack end from the neutral state to full steering. A steering structure for a vehicle, wherein the length is formed to be 1/2 to 1/3. 2. The steering gear case according to claim 2, wherein the elastic body is a spring, and the rack boot mounting portion of the steering gear case is provided with a lip for holding the spring, and the end of the spring on the steering gear case side is the end of the steering gear case. The vehicle steering structure according to claim 1, wherein the vehicle is integrally fixed to the rack boot. 3. An end portion of the steering gear case is provided with an extension extending in the axial direction, and an end of the spring is press-fitted and fixed to an inner peripheral surface of the extension. The vehicle steering structure according to claim 1, wherein: