JPH11255130A - Adjusting structure of rack damper screw - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make friction between a rack and a pinion variable correspondingly to the vehicle speed. SOLUTION: A pinion 7 arranged inside the gear box 5 of a steering gear is meshed with a rack 8 extending in the vehicle width direction and the circumferential lateral of the rack 8 has a plunger 9 abutting on it. The plunger 9 is pushed to the rack 8 side by a damper screw 12 through a spring 11 provided with compression. The damper screw 12 is provided with a gear 14 composed of a worm wheel and a worm gear 15 meshed with the gear 14 is connected to a motor to adjust the tightening of the damper screw 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rack damper screw adjusting structure for easily adjusting friction between a rack and a plunger of a steering device of an automobile.

[0002]

2. Description of the Related Art FIG. 10 shows an internal structure of a rack and pinion type gear box 51 of a steering device.
The gear box 51 is provided with a pinion 53 fixed to the tip of a steering shaft 52, and the pinion 53 meshes with the teeth of a rack 54. A cylindrical portion 55 of the gear box 51 includes a rack damper screw (hereinafter referred to as a damper screw) 56 having a threaded peripheral portion, and a cylindrical portion 55.
A plunger 57 capable of moving on the inner wall of the cylindrical portion 55 is provided, and the damper screw 56 is screwed into a screw portion 55 a formed on the inner wall of the cylindrical portion 55. A spring 58 is provided between the damper screw 56 and the plunger 57, and the plunger 57 is urged toward the rack 54 via a spring force. In the gear box 51 having such a configuration, the turning power from the handle is provided via the steering shaft 52, transmitted to the pinion 53 and the rack 57, and converts the rotational motion into a linear motion.

Normally, friction adjustment of the steering system is performed by adjusting the pressing force of the plunger 57 which urges the rack 54 toward the pinion.
This pressing force is adjusted by the amount of tightening of the damper screw 56. That is, if the damper screw 56 is turned in the tightening direction, the handle operation becomes heavy, and if it is loosened, the handle operation becomes light. In the running state of the automobile, it is better that the friction is small in order to improve the return of the steering wheel at low speed. In addition, in order to improve the sitting feeling of the steering wheel at a high speed, it is preferable that the friction is increased and the tightening amount is larger than at a low speed.

[0004]

However, once the damper screw is adjusted, it is usually maintained in the same state, and the magnitude of the friction does not change. Therefore, in order to make adjustments in accordance with the traveling state, the adjustments must be made each time, but in reality, the adjustments are not performed because it takes time and effort. Japanese Patent Publication No. 62-4269 No.
Using springs and steel balls, the attraction force of the electromagnet has been proposed to change the urging force of the steel balls urging the rack, but even if the current value to the electromagnet is changed, It is not possible to make fine initial (initial load) adjustments or fine adjustments of the biasing force.

The present invention has been made in view of the above problems, and has as its object to provide an adjustment structure of a rack damper screw that can change the urging force on a rack according to the vehicle speed of an automobile.

[0006]

In order to achieve the above object, the present invention provides a pinion disposed on a steering gear case, a rack meshing with the pinion, a plunger for pressing the rack toward the pinion, and a screw. And a rack damper screw for pressing the plunger toward the rack by the pushing amount of the part, a driving motor is provided in parallel with the screw part, and the pushing amount of the screw is adjusted by controlling the driving motor. I made it.
According to another aspect of the present invention, there is provided a pinion disposed in a steering gear case, a rack meshing with the pinion, a plunger pressing the rack toward the pinion, and an inner wall of the steering gear case. A structure in which a screw portion is screwed into the screw portion, and a rack damper screw that presses the plunger toward the rack side by the amount of tightening of the screw portion, while providing a gear portion to the rack damper screw,
A drive motor for rotating the gear portion is provided, and the screwing amount of the screw portion is changed by the rotation of the gear portion to adjust the pressing force of the plunger against the rack.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an adjustment structure of a rack damper screw according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a steering device 2 of an automobile 1. The steering device 2 includes a steering wheel 3
A gear box 5 for changing the rotational movement of the gear box into a linear movement is provided. 2 to 4 are enlarged views of the gear box 5. A rod 6 for transmitting the rotation of the handle 3 is housed inside the gear box 5, and a pinion 7 is fixed to a distal end of the rod 6. The pinion 7 is a rack 8 extending in the vehicle width direction.
The plunger 9 is in contact with the peripheral side of the rack 8. The plunger 9 is disposed so as to be slidable in a cylindrical portion 10 provided in the gear box 5, and receives a damper screw 1 through a spring 11 provided in a compressed state.
2 presses against the rack 8 side.

FIGS. 5 to 7 show the damper screw 12. The damper screw 12 is formed of a screw portion 13 and a gear portion 14, has a substantially cylindrical shape with a screw portion 13, has a male screw 13 c formed on the periphery thereof, and has a screw 10 a formed on the inner wall of the cylindrical tube portion 10. I agree. The damper screw 12 can adjust the pressing force of the plunger 9 according to the tightening amount of the male screw 13c. The screw portion 13 is provided with a serration shaft 13a, and a square hole 13b is formed in the shaft.
The gear portion 14 is fitted to a serration shaft (or a spline shaft) 13a of the screw portion 13 and fixed by a bolt (not shown).

A worm wheel 14a is formed partially or entirely on the periphery of the disc-shaped gear portion 14, and a worm gear 15 meshes therewith. The worm gear 15 is a motor 1 provided in the gear box 5 as shown in FIG.
6 is fixed to the rotating shaft 17. As the motor 16, a motor that can adjust the phase angle of the rotating shaft 17, for example, a stepping motor is used. The motor 16 is connected to a control box 19 by lead wires 18a and 18b, and the control box 19 is connected to a meter or a vehicle speed sensor for ABS. The vehicle speed sensor is conventional and is not shown. The control box 19 can control the phase angle and the rotation speed of the motor in response to the vehicle speed signal. The relationship between the vehicle speed and the amount of tightening of the damper screw 12 is such that the amount of tightening increases as the vehicle speed increases. That is, it is only necessary that the relation that the differential value of dθ / dV is larger than 0, where θ is the tightening angle of the screw portion and V is the vehicle speed.

Next, the operation of the rack damper screw adjusting structure will be described. For example, when the speed of the car 1 changes from a state in which the vehicle is traveling in the medium speed range to a low speed range,
The control box 19 detects a change in vehicle speed based on a signal from the vehicle speed sensor. Next, the phase angle and the number of rotations of the motor 16 are calculated so that the plunger 9 applies an appropriate pressing force to the rack 8, and the worm gear 15 is rotated by a necessary amount based on the calculation result. When the automobile 1 is traveling at a low speed, the pressing force of the plunger 9 is reduced. Therefore, the worm gear 15 is rotated in a direction in which the damper screw 12 extends the spring 11.
That is, the rotation of the worm gear 15 receives the rotation of the worm wheel 14a meshing with the worm gear 15, and the damper screw 12 rotates in a direction to loosen the screw, thereby reducing the pressing force of the plunger 9 against the rack 8.

When the speed of the vehicle 1 changes from a low speed range to a high speed range, the control box 19 detects a change in vehicle speed from a vehicle speed sensor. Next, the phase angle and the number of rotations of the motor 16 are calculated so that the plunger 9 applies an appropriate pressing force to the rack 8, and the worm gear 15 fixed to the rotating shaft 17 by a required amount is calculated from the result. Rotate. When the automobile 1 is traveling at high speed, it is desirable to increase the pressing force of the plunger 9. Therefore, the worm gear 15 rotates in the direction in which the damper screw 12 contracts the spring 11. That is,
The rotation of the worm gear 15 causes the rotation of the worm wheel 14a meshing with the worm gear 15 to rotate the damper screw 12 in the direction of tightening the screw, thereby increasing the pressing force of the plunger 9 against the rack 8.

As described above, in the present embodiment, the automobile 1
The amount of tightening of the damper screw 12 can be changed according to the vehicle speed of the vehicle, so that the steering operation is improved by appropriate friction. That is, the return of the steering wheel is improved at a low speed, and the sitting feeling of the steering wheel is improved at a high speed. In addition, since the serrated shaft 13a is provided with the square hole 13b, adjustment at the time of assembling the screw portion 13 and at the time of service can be easily performed with an existing tool. Further, since the gear portion 14 is fitted to the serration shaft 13a, the positioning of the gear portion 14 can be easily performed.

Next, a second embodiment of the present invention will be described with reference to FIG. As shown in the figure, a long hole (may be a long groove) 22 is formed on the gear portion 21 on the same circumference. A cylindrical portion 24 of a gear box into which the screw portion 23 is screwed is provided on a peripheral portion of the screw portion 23, and a convex portion 24 b fitted into the long hole 22 is provided on a wall portion 24 a thereof.
Is formed. The screw 23 and the gear 2
In FIG. 1, marks 25a and 25b for initial positioning are provided, and the initial positions are aligned with the convex portions 24b.

Next, the operation of the second embodiment of the present invention will be described. In the present embodiment, since the long hole 22 is formed in the gear portion 21, when the gear portion 21 rotates, the gear portion 21 may rotate beyond a predetermined amount due to a malfunction of the system. Even if there is, a long hole 22 is formed in the convex portion 24b.
Is locked. Therefore, it is possible to prevent the screw portion 23 from being excessively tightened or loosened. In addition, the length of the long hole 22 is formed so as to match the moving range of the screw portion 23. Since the positioning marks 25a and 25b formed of the concave and convex portions are formed, the initial position of the screw portion 23 and the gear portion 21 can be easily positioned.

Although the embodiments of the present invention have been described above, the present invention is, of course, not limited thereto, and various modifications can be made based on the technical concept of the present invention. FIG.
The gear portion 31 is not circular, but has a fan shape in which only necessary portions of the teeth of the worm wheel 32 are formed on the outer peripheral portion.
This is effective when arranging a circular gear portion at a position where it cannot be arranged. In the above embodiments, the screw part and the gear part are divided into two parts, but they may be integrally formed. Further, in the first embodiment described above, the amount of tightening of the damper screw is adjusted in three stages of low, medium, and high speed, but may be switched to two or four or more stages. Alternatively, it may be changed in an analog manner according to the tightening amount. Further, a worm wheel was provided on the screw portion to adjust the pushing amount of the screw portion.
A cam may be provided on the turning shaft 17 to adjust the pushing amount of the screw portion.

[0016]

As described above, since the rack damper screw is provided with the gear portion and the driving means for rotating the gear portion is provided, the amount of tightening of the rack damper screw is changed by the rotation of the gear portion. Thus, the pressing force of the plunger against the rack can be adjusted. Therefore, the rack and the pinion can obtain an appropriate friction, and the handle operation can be improved. The return of the handle can be improved at a low speed of the vehicle, and the sitting feeling of the handle can be improved at a high speed.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a steering apparatus of an automobile adopting a rack damper screw adjusting structure according to a first embodiment of the present invention.

FIG. 2 is a side view of a gear box accommodating a rack damper screw according to the embodiment of the present invention.

FIG. 3 is a sectional view of a gear box accommodating a rack damper screw according to the embodiment of the present invention.

FIG. 4 is a sectional view taken along line XX in FIG. 2;

FIG. 5 is a perspective view of a screw portion housed in the gear box of FIG. 2;

FIG. 6 is a plan view showing a state in which a worm wheel of a damper screw accommodated in FIG. 2 and a worm gear fixed to a motor shaft are engaged.

FIG. 7 is a sectional view taken along line YY in FIG. 6;

FIG. 8 is an exploded perspective view of a damper screw of a rack damper screw adjustment structure according to a second embodiment of the present invention.

FIG. 9 is a plan view of a gear portion of a damper screw according to a modification of the present invention.

FIG. 10 is a sectional view of a conventional damper screw.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Automobile 2 Steering device 5 Gear box 6 Rod 7 Pinion 8 Rack 9 Plunger 10, 24 Tube part 11 Spring 12 Damper screw 13, 23 Screw part 13a Serration shaft 13b Square hole 14, 21, 31 Gear part 14a, 32 Worm wheel 15 Worm gear 16 Motor 22 Slot 24b Convex 25a, 25b Alignment mark

Claims (4)

[Claims] 1. A pinion disposed in a steering gear case, a rack that meshes with the pinion, a plunger that presses the rack toward the pinion, and a rack damper that presses the plunger toward the rack by a pushing amount of a screw portion. A screw damper screw adjusting structure, wherein a driving motor is provided in parallel with the screw part in the structure including the screw, and the amount of pushing of the screw is adjusted by controlling the driving motor. 2. A pinion disposed on a steering gear case, a rack that meshes with the pinion, a plunger that presses the rack toward the pinion, and a screw portion screwed into a screw portion formed on an inner wall of the steering gear case. And a rack damper screw that presses the plunger toward the rack by the amount of tightening of the screw portion, wherein a gear portion is provided on the rack damper screw, and a drive motor that rotates the gear portion is provided. An adjustment structure for a rack damper screw, characterized in that a screwing amount of a screw portion is changed by rotating a gear portion to adjust a pressing force of a plunger against a rack. 3. A screw part and a gear part of the rack damper screw are separately formed, these are fitted and integrated, and teeth formed on the gear part are partially provided, and the screw part, the gear part, The rack damper screw adjusting structure according to claim 2, wherein a positioning alignment mark is provided on the steering gear case. 4. The rack damper screw adjusting structure according to claim 3, wherein a concentric hole or groove is formed in the gear portion, and a projection engaging with the hole or groove is provided in the steering gear case.