JPH072363Y2 - Rack bar connection structure for four-wheel steering system - Google Patents

Description

[Detailed Description of the Invention] (Industrial field of application) The present invention inputs the linear motion of the rack bar according to the steering operation via the link lever, and when the front wheel steering angle is small, the rear wheels are in the in-phase direction. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rack bar connecting structure of a four-wheel steering device that steers rear wheels in opposite phases when the steering angle of front wheels increases.

(Prior Art) Conventionally, the steering linkage of the front wheels and the steering linkage of the rear wheels are mechanically connected, and when the steering angle of the front wheels is small, the rear wheels are steered in the same phase direction, and when the steering angle of the front wheels becomes large, the rear wheels are steered. As a four-wheel steering device for steering in a reverse phase direction, for example, a linear motion of a rack bar in a front steering gear box is converted into a rotary motion,
This rotary motion is input to the rear steering box via the center shaft, and the rear steering wheel is steered in the same phase direction up to a steering wheel turning angle of 140 ° by a gear mechanism that applies the planetary gear mechanism incorporated in the rear steering gear box. Then
A device has been developed that allows the rear wheels to be steered in the opposite phase when the steering angle exceeds 140 ° (Motor Fan
December 1986, pp. 119-122, "What is 4WS Honda's four-wheel steering system?"

In such a four-wheel steering system, since the rear wheels are steered in the same phase as the front wheels during high-speed traveling with a small steering wheel turning angle, there is no vehicle body roll, for example, in a lane change, which is excellent. On the other hand, when steering the garage into the garage, the steering wheel is turned to a large extent to steer the rear wheels in the opposite direction to the front wheels, reducing the turning radius of the vehicle and allowing a small turn. Will be easier.

However, in such a conventional four-wheel steering system, the mechanical structure is relatively complicated, and the rear steering gear box itself becomes large in size, resulting in an increase in weight and cost. For those who
A four-wheel steering system is proposed that allows the rear wheels to be switched from the in-phase direction to the anti-phase direction in response to an increase in the front wheel steering angle by a simple mechanical structure using a rack and pinion mechanism as shown in FIG. is doing.

In FIG. 3, the front steering gear box 1
The linear motion associated with the steering operation of the rack bar provided in the vehicle is converted into the linear motion in the vehicle front-rear direction by the L-shaped link lever 2 and the rod 3 and transmitted to the housing 5 of the rear steering gear box 4, and is then stored in the housing 5. The pinion gear 6 that moves integrally is rotatably incorporated. A fixed rack bar 7 having one end fixed to the vehicle body is meshed with the pinion gear 6, and the housing 5
The pinion gear 6 meshed with the fixed rack bar 7 is rotated by the linear movement of the rear wheel cutting angle characteristic A obtained by the sine movement component by the rotation of the pinion gear 6 and the housing 5 as shown in FIG. The combined characteristic C with the rear wheel turning angle characteristic B obtained by the linear movement component is taken out by the link arm 8 attached to the rotating shaft of the pinion gear 6 and transmitted to the rear steering linkage via the rod 9. as a result,
As shown by the characteristic C in FIG. 4, the rear wheel turning angle can be switched from the same phase (+ side) to the opposite phase (− side) mechanically in conjunction with the front wheel steering in accordance with the increase in the steering wheel angle. .

(Problems to be solved by the invention) By the way, in the new four-wheel steering system as shown in FIG. 3, the linear motion of the rack bar provided in the conventional front steering gear box is changed to L-shape. A new connecting structure is required for transmission to the link bar, and it is desirable that the connecting structure with the rack bar is a connecting structure that minimizes changes in the mechanical structure of the conventional front steering gear box.

(Means for Solving Problems) The present invention has been made in view of such a situation. With the adoption of a new four-wheel steering device, the connection with the rack bar is changed from the conventional structure. An object of the present invention is to provide a rack bar connecting structure for a four-wheel steering device which is structurally simple and robust while being minimized.

In order to achieve this object, in the present invention, a link lever for a four-wheel drive device, in which a slide groove is formed on the outer periphery of a socket of a ball joint fixed to one shaft end of a rack bar, and the tip is divided into two forks. The arm portion is pivotally attached to a slide piece inserted in a slide groove on the outer periphery of the socket so as to be rotatably connected.

(Operation) According to the rack bar connecting structure of the four-wheel steering device of the present invention, the link on the four-wheel steering device side is formed by using the ball joint that connects the side rod to the shaft end of the rack bar. Since the lever is rotatably connected, the connecting structure can be realized simply by changing the outer shape of the socket of the ball joint in the conventional structure, and the slide inserted in the slide groove formed on the outer circumference of the socket. Since the arm part of the link lever whose tip is divided into two forks need only be pivotally attached to the piece with a pin, mechanical connection with the slide groove of the sickle is not required, and both can be connected by a simple fit. Can be easily assembled, and a structurally robust connection structure can be obtained.

(Embodiment) FIG. 1 is a sectional view showing an embodiment of the present invention.
Fig. 2 shows the II-II section taken out.

First, the structure will be described. 10 is a rack bar housing, and a rack bar 11 which is linearly driven by a steering operation is slidably incorporated in the rack bar housing 10 and is taken out from the rack bar housing 10. A ball joint 12 for connecting a tie rod 13 is provided at the shaft end of the rack bar 11. The ball joint 12 is a tie rod with a bearing 15 in a socket 14.
A spherical portion 16 formed integrally with the shaft end of 13 is swingably incorporated. A screw part 17 is integrally formed on the bottom side of the socket 14, and the screw part 17 is screwed into a screw hole 18 formed at the shaft end of the rack bar 11 to fix the ball joint socket to the rack bar 11. There is.

Although the structure in which the rack bar 11 and the tie rod 13 are connected by the ball joint 12 is the same as the conventional structure,
In addition to this, in the present invention, as the socket 14 in the ball joint 12, one having a large diameter is used as shown in the drawing, and an annular slide groove 19 is formed on the outer periphery of the socket 14, and this slide groove 19 is used. A link arm connecting structure for transmitting the linear driving force of the rack bar 11 to the rear steering gear box is realized.

A pair of slide pieces 20 are inserted into the slide grooves 19 formed on the outer periphery of the socket 14, and as shown in FIG. 2, the L-shaped link lever 2 having a forked end is inserted into the slide pieces 20. The arm portion (21) at one end is rotatably connected by fitting the pin (22) into the slide piece (20).

As shown in FIG. 3, the L-shaped link lever 2 is rotatably mounted on a shaft whose corner portion is mounted on the vehicle body side. Therefore, as is apparent from FIG. The shaft 24 is fixed and the shaft portion 25 of the bolt shaft 24 is fitted with the shaft hole 26 provided in the corner portion to be rotatably mounted.

Further, as shown in FIG. 1, a boot seal 27 is assembled so as to cover the connecting portion between the rack bar housing 11 and the tie rod 13, and the boot seal 27 is attached to the socket 14 of the L-shaped link lever 2 at the connecting portion. As shown in FIG. 2, a boot portion 27a extends to the L-shaped link lever 2 side, and has a T-shaped boot shape when seen in a plan view.

Next, the operation of the above embodiment will be described.

First, the assembly of the rack bar connecting structure of the present invention will be described. On the rack bar 11 side, it can be carried out independently of the assembly of the L-shaped link bar 2 for steering the rear wheels. The rack bar 11 and the tie rod 13 can be connected by screwing a threaded portion 17 integrally formed on the bottom side of the socket 14 of the ball joint 12 at the end into a screw hole 18 at the shaft end of the rack bar 11. it can.

When the assembling position adjustment of the tie rod 13 by the ball joint socket 12 to the rack bar 11 is completed in this way, as shown in FIG.
The pin 22 is fitted into the bifurcated arm part 21 at the tip of the ball, the slide piece 20 is fitted into the pin 22, and the slide groove formed on the outer circumference of the socket 14 of the ball joint 12 is inserted.
The slide piece 20 attached to the arm portion 21 by the pin 22 is laterally fitted in the pin 19 and is inserted into the slide groove 19 of the slide piece 20 to be inserted into the shaft hole 26 of the corner portion of the L-shaped link lever 2. Insert the axle bolt 24 into the vehicle body
L to the rack bar 11 by screwing and fixing to 23
The assembly of the character-shaped link lever 2 can be completed.

Next, the movement of the L-shaped link lever 2 with respect to the linear drive of the rack bar 11 will be described. The rack bar 11 is linearly driven to the rack bar housing 10 in either the left or right direction according to the steering operation, and is integrated with the rack bar 11. Since the socket 14 of the ball joint 12 also moves, the slide piece 20 fitted in the slide groove 19 of the socket 14 moves according to the rack bar 11. The movement of the slide piece 20 is transmitted to the arm portion 21 via the pin 22, and as a result,
The L-shaped link lever 2 rotates about the shaft bolt 24 in response to the linear drive of the rack bar 11. Slide groove 19
The slide piece 20 is inserted into the rack bar 11 by rotating the L-shaped link arm 2 about the shaft bolt 24, and the slide piece 20 is simply inserted into the socket 14. Since the rack bar 11 is merely inserted into the slide groove 19, the movement of the rack bar 11 within the range where the slide bar 19 is not separated can be converted into the rotation amount of the L-shaped link lever 2. Therefore, no twist is generated in the connecting portion that converts the linear motion of the rack bar 11 into the rotational motion of the L-shaped link lever 2, and the reaction force acting on the rack bar 11 when the L-shaped link lever 2 is rotated is the rack. Since it acts only in the axial direction of the bar 11, the linear motion of the rack bar 11 is smoothly converted into the rotational motion of the L-shaped link lever 2 without the bending stress of the rack bar 11 and the rear steering gear box is formed. Can be communicated.

(Effect of the Invention) As described above, according to the present invention, the arm of the link lever is formed with the slide groove formed on the outer circumference of the socket of the ball joint fixed to one shaft end of the rack bar, and the tip is divided into two. Since the parts are pivotally connected to the slide piece inserted in the slide groove on the outer periphery of the socket so that they can be freely rotatably connected, the connection structure for connecting the rack bar and the tie rod using the ball joint was changed in the conventional front steering linkage. Without changing the outer shape of the socket of the ball joint and forming the slide groove on the outer circumference of the socket, it is possible to realize the coupling structure for transmitting the driving force for the rear wheel steering control.

Further, as a connecting structure for converting the linear motion of the rack bar into the rotary motion of the link lever, a slide piece is fitted in a slide groove on the outer periphery of the socket, and an arm which is divided into two forks at the tip of the link lever by a pin with respect to this slide piece. Since the structure is such that the link part is pivotally attached, the change in the connecting position due to the rotation of the link lever is not absorbed by the movement of the slide piece with respect to the slide groove, and no twisting occurs in the connecting part. Since the reaction force against the rack bar acts only in the axial direction even when the rack is rotated, bending stress does not act on the rack bar, and the front wheel steering by the linear drive of the rack bar is not hindered for rear wheel steering. The driving force can be extracted from the rack bar and transmitted to the rear steering gearbox.

[Brief description of drawings]

FIG. 1 is an explanatory sectional view showing an embodiment of the present invention, FIG. 2 is a sectional view taken along line II-II of FIG. 1, and FIG. 3 is a four-wheel steering device proposed by the inventors of the present application. FIG. 4 is a control characteristic diagram of the rear wheel turning angle by the four-wheel steering system of FIG. 1: Front steering gear box 2: L-shaped link lever 3,9: Rod 4: Rear steering gear box 5: Housing 6: Pinion gear 7: Fixed rack bar 8: Link lever 10: Rack bar housing 11: Rack bar 12: Ball joint 13: Tie rod 14: Socket 15: Bearing 16: Ball part 17: Screw part 18: Screw hole 19: Slide groove 20: Slide piece 21: Arm part 22: Pin 23: Body side 24: Shaft bolt 25: Shaft part 26: Shaft hole

Claims (1)

[Scope of utility model registration request] 1. A linear motion of a rack bar according to a steering operation is input via a link lever to steer the rear wheels in the in-phase direction when the front wheel steering angle is small, and the rear wheels when the front wheel steering angle becomes large. In a rack bar connecting structure for a four-wheel steering device that steers in the opposite phase direction, a slide groove is formed on the outer circumference of a socket of a ball joint fixed to one shaft end of the rack bar, and the tip is divided into two forks. A rack bar connecting structure for a four-wheel steering device, wherein the arm portion of the link lever is rotatably connected to the slide piece inserted in the slide groove by pivotal attachment.