JP2001239944A - Joining structure of telescopic shaft - Google Patents

Abstract

PROBLEM TO BE SOLVED: To minimize sliding resistance of both shafts, to surely prevent looseness of both shafts, and to excellently maintain the feeling in steering operation (steering). SOLUTION: An outer shaft 2 is fitted to an inner shaft 1 so as to be nonrotatable and freely slidable in the shaft direction. A shaft directional opening 6 extending in the shaft direction is formed in the outer shaft 2. A rolling body 3 is arranged in this shaft directional opening 6. An elastic body 8 for pressing this rolling body 3 to the inner shaft 1 is installed on an outer peripheral surface of the outer shaft 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a joint structure of a telescopic shaft used for a steering device of an automobile.

[0002]

2. Description of the Related Art A steering apparatus for a vehicle includes a tilt type steering apparatus capable of adjusting a tilt angle of a steering wheel according to a driver's driving posture, and a telescopic type steering apparatus capable of adjusting an axial position of the steering wheel. There is a device.

At the time of this tilt or telescopic adjustment,
The lower shaft connected to the steering gear at the bottom of the vehicle slightly changes in axial length due to the tilting or telescopic sliding of the upper shaft, so that the change in axial length can be tolerated. , An inner shaft and an outer shaft spline-fitted to the inner shaft.

In such a telescopic shaft, the sliding resistance of both shafts varies depending on the product,
Since "play" may occur in both shafts, the sliding resistance of both shafts is adjusted and "play" in both shafts is prevented.

For example, in Japanese Utility Model Laid-Open Publication No. 61-28918, a plurality of rolling elements are arranged by partially flattening the outer peripheral surface of an inner shaft, and these rolling elements are mounted on the inner peripheral surface of an outer shaft. An elastic body to press is attached. These rolling elements reduce the sliding resistance in the axial direction, and the elastic body elastically presses the inner shaft via the rolling elements, thereby preventing the backlash of both shafts. During steering operation (steering), a small steering torque is transmitted between the two shafts via the rolling elements and the elastic body, while a large steering torque is transmitted via the spline teeth.

In US Pat. No. 4,911,034, an axial opening extending in an axial direction is formed in an outer shaft, and a leaf spring is disposed in the axial opening, and an outer peripheral surface of the outer shaft is formed. Further, a spring ring is mounted so as to press this leaf spring against the inner shaft. The spring ring elastically presses the inner shaft together with the leaf spring, thereby preventing the backlash of both shafts.

[0007]

However, in the telescopic shaft disclosed in Japanese Utility Model Laid-Open Publication No. Sho 61-28918, the rolling element and the elastic body are arranged inside the outer shaft, so that it is inevitable. In some cases, the diameter of the inner shaft must be relatively small, and the structure disclosed in the publication cannot be adopted for a practically large inner shaft. After the two shafts have been assembled, the elastic body has been inserted inside the outer shaft.After that, the elastic force of the elastic body can be changed to adjust the sliding resistance of both shafts. There is no such thing.

Further, in the above-mentioned US Pat. No. 4,911,034, a spring ring on the outer side of the outer shaft elastically presses the inner shaft together with the leaf spring, which is extremely effective in preventing "play". However, on the other hand, the sliding resistance of both shafts may be too large.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described circumstances, and it has been found that the sliding resistance of both shafts is extremely low, and that "shaking" of both shafts is reliably prevented. An object of the present invention is to provide a joint structure of a telescopic shaft that can maintain good feel during operation (steering).

[0010]

In order to achieve the above-mentioned object, the present invention relates to a joint structure of a telescopic shaft according to the present invention, wherein the joint structure of a shaft which is axially extendable and non-rotatably coupled is an inner shaft. The outer shaft is fitted non-rotatably and slidably in the axial direction, an axial opening extending in the axial direction is formed in the outer shaft, a rolling element is disposed in the axial opening, and the outer An elastic body is mounted on the outer peripheral surface of the shaft so as to press the rolling element against the inner shaft.

As described above, according to the present invention, when the axial length of both shafts is allowed to vary during the tilt or telescopic adjustment, the rolling element is connected to the elastic body and the inner shaft along the axial opening. , The sliding resistance can be extremely low.

Further, since the elastic body elastically presses the outer shaft against the inner shaft via the rolling element, "play" between the two shafts can be reliably prevented. Note that, for example, "play" due to minute gaps between spline teeth can be reliably prevented.

Further, during steering operation (steering), a small steering torque can be transmitted between the two shafts via the rolling element and the elastic body, while a large steering torque is
The transmission can be performed via the spline teeth, and the feel during steering can be maintained well.

[0014]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an exploded perspective view showing a connecting structure of a telescopic shaft according to an embodiment of the present invention. (First Embodiment) FIG. 1A is a plan view of a vehicle steering shaft to which a connecting structure of a telescopic shaft according to a first embodiment of the present invention is applied, and FIG.
It is the longitudinal section, and (c) is the transverse section. FIG. 2 is a longitudinal sectional view of the vehicle steering shaft shown in FIG. 1 and shows both shafts in the most extended state.

As shown in FIGS. 1 and 2, an outer shaft 2 is splined or serrated fitted to an inner shaft 1. The inner shaft 1 is formed with a concave rail groove 4 extending in the axial direction so that a ball rolling element 3 described later can be rolled, and the periphery of the rail groove 4 is shown in FIG. A flat portion 5 is formed in a range indicated by a broken line in FIG. The end of the flat portion 5 acts as a stopper for the ball rolling element 3 (more specifically, a retainer 7 described later).

The outer shaft 2 has the rail groove 3
An axial opening 6 extending in the axial direction is formed corresponding to. A plurality of (for example, two) ball rolling elements 3 are housed in the axial opening 6. The rolling elements 3 of these balls are held by a cage 7 (cage) maintained at a predetermined interval, and the cage 7 also serves as a stopper for the rolling elements 3 when the shafts 1 and 2 rotate. It has become. The end of the opening 6 serves as a stopper for the ball rolling element 3 (more specifically, the retainer 7).

A C-shaped spring ring 8 for elastically pressing the ball rolling element 3 against the inner shaft 1 is mounted on the outer peripheral surface of the outer shaft 2. The spring ring 8 is formed with a concave portion 9 as a guide portion for guiding the rolling element 3 of the ball. The concave portion 9 is used when the shafts 1 and 2 rotate and when the shafts 1 and 2 rotate. , And also serves to stop the rolling element 3 from rotating. The end of the recess 9 acts as a stopper for the ball rolling element 3.

With the above configuration, when the axial length of the shafts 1 and 2 is allowed to vary during tilt or telescopic adjustment, the ball rolling element 3 moves along the axial opening 6. Therefore, the rolling resistance is reduced between the spring ring 8 and the rail groove 4 of the inner shaft 1, so that the sliding resistance can be extremely reduced.

Further, the spring ring 8 is
Is elastically pressed against the inner shaft 1 via the rolling elements 3 of the ball, so that the "play"
Can be reliably prevented. In addition, both shafts 1,
The "play" due to the minute gap between the two spline teeth can be reliably prevented.

Further, at the time of steering operation (steering), if the steering torque is small, the ball rolling element 3
While being elastically pressed between the recess 9 of the spring ring 8 and the rail groove 4 of the inner shaft 1, for example, upon receiving a steering torque from the inner shaft 1, through the end face of the axial opening 6 of the outer shaft 2. , To the outer shaft 2. On the other hand, when the steering torque is large, it can be transmitted via the spline teeth of both shafts 1 and 2. Thereby, the feeling at the time of steering can also be favorably maintained.

Further, as shown in FIG. 2, when both shafts 1 and 2 are in the most extended state, one end of the retainer 7 abuts on the end face of the flat portion 5 of the inner shaft 1 and the other end of the retainer 7 Abuts against the end face of the axial opening 6 of the outer shaft 2, whereby the end face of the flat portion 5 and the end face of the axial opening 6 act as stoppers, and are held in contact with the ball rolling element 3. The device 7 can be prevented from falling out. (Second Embodiment) FIG. 3A is a longitudinal sectional view of a vehicle steering shaft to which a connecting structure of a telescopic shaft according to a second embodiment of the present invention is applied, and FIG.
Is a cross-sectional view thereof.

In the second embodiment, the ball rolling element 3 and the retainer 7 shown in the first embodiment are provided at two locations facing each other in the radial direction. In this case, the sliding resistance can be further reduced, the "play" can be more reliably prevented, and the feel during steering can be maintained satisfactorily. The opening of the C-shaped spring ring 8 is arranged at a position not corresponding to the rolling element 3 of the ball.

FIG. 4A is a cross-sectional view of a vehicle steering shaft according to a first modification of the second embodiment. In the first modification, the opening of the C-shaped spring ring 8 is
It is tightened by bolts 10. By changing the tightening force of the bolt 8, the elastic force of the spring ring 8 can be adjusted, and the sliding resistance of the shafts 1 and 2 can be adjusted.

FIG. 4B is a cross-sectional view of a vehicle steering shaft according to a second modification of the second embodiment. In the second modified example, instead of the C-shaped spring ring 8,
A seamless O-shaped spring ring 8 is used. This O
The mold spring ring 8 may be fitted at the end of assembly. (Third Embodiment) FIG. 5A is a vertical sectional view of a vehicle steering shaft to which a telescopic shaft coupling structure according to a third embodiment of the present invention is applied, and FIG.
Is a cross-sectional view thereof. FIG. 6 is a schematic view showing a state where the vehicle steering shaft shown in FIG. 5 is assembled.

In the above-described embodiment, the number of rolling elements 3 for balls is two, but in the third embodiment, three rolling elements are used. Also, a rail groove 4 of the inner shaft 1 and
The recess 9 of the spring ring 8 has a flat contact surface with the rolling element 3. Also in this case, the sliding resistance can be further reduced, the "play" can be more reliably prevented, and the feel at the time of steering can be maintained satisfactorily.

As shown in FIG. 6, at the time of assembly, after the outer shaft 2 is spline-fitted to the inner shaft 1, the ball rolling element 3 and the retainer 7 are attached to the axial opening 6 of the outer shaft 2. Then, the spring ring 8 is fitted on the outer peripheral surface of the outer shaft 2.

FIG. 7 is a cross-sectional view of a vehicle steering shaft according to a first modification of the third embodiment. In the first modified example, a roller (or a needle roller) is used as the rolling element 3. Also in this case, the sliding resistance can be further reduced, the "play" can be more reliably prevented, and the feel at the time of steering can be maintained satisfactorily.

The present invention is not limited to the above-described embodiment, but can be variously modified.

[0029]

As described above, according to the present invention,
When the axial length of both shafts is allowed to fluctuate during tilt or telescopic adjustment, the rolling element rolls between the elastic body and the inner shaft along the axial opening, so that the sliding resistance is extremely low. be able to.

Further, since the elastic body elastically presses the outer shaft against the inner shaft via the rolling elements, "play" between the two shafts can be reliably prevented. Note that, for example, "play" due to minute gaps between spline teeth can be reliably prevented.

Further, at the time of steering operation (steering), a small steering torque can be transmitted between both shafts via the rolling element and the elastic body, while a large steering torque is
The transmission can be performed via the spline teeth, and the feel during steering can be maintained well.

[Brief description of the drawings]

1A is a plan view of a vehicle steering shaft to which a telescopic shaft coupling structure according to a first embodiment of the present invention is applied, and FIG. 1B is a longitudinal sectional view thereof; (C) is a cross-sectional view thereof.

FIG. 2 is a longitudinal sectional view of the vehicle steering shaft shown in FIG. 1, showing both shafts in the most extended state.

FIG. 3A is a longitudinal sectional view of a vehicle steering shaft to which a joint structure of a telescopic shaft according to a second embodiment of the present invention is applied, and FIG. 3B is a transverse sectional view thereof. .

FIG. 4A is a cross-sectional view of a vehicle steering shaft according to a first modification of the second embodiment, and FIG.
It is a cross-sectional view of a vehicle steering shaft according to a modification.

FIG. 5A is a longitudinal sectional view of a vehicle steering shaft to which a joint structure of a telescopic shaft according to a third embodiment of the present invention is applied, and FIG. 5B is a transverse sectional view thereof. .

FIG. 6 is a schematic diagram showing a state in which the vehicle steering shaft shown in FIG. 5 is assembled.

FIG. 7 is a cross-sectional view of a vehicle steering shaft according to a first modification of the third embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Inner shaft 2 Outer shaft 3 Rolling element 4 Rail groove 5 Flat part 6 Axial opening 7 Cage 8 Spring ring 9 Depression 10 Bolt

Claims (1)

[Claims] 1. A coupling structure of a shaft which is axially expandable and contractable and non-rotatably coupled, wherein an outer shaft is non-rotatably and axially slidably fitted to an inner shaft; An axial opening extending in the direction is formed, a rolling element is disposed in the axial opening, and an elastic body is mounted on the outer peripheral surface of the outer shaft so as to press the rolling element against the inner shaft. The coupling structure of a telescopic shaft.