JP2004316823A - Extensible shaft - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress the looseness of the spline-fitting of an extensible shaft and also suppress sliding resistance. <P>SOLUTION: On a countershaft 2 as this extensible shaft, the end part 14a of an inner shaft part 14 is inserted into a fitting hole 13b at the end part 13a of an outer shaft part 13 for spline fitting. An elastic deformation part 18 is formed on the outer shaft part 13 by local pressing, and the diameter reduced part 13e of the outer shaft part 13 corresponding to the elastic deformation part 18 is tightened by a generally annular tightening member 19. The contact engagement part 18b of the elastic deformation part 18 is engaged with the corresponding portion 14c of the inner shaft part 14 without radial looseness and allows the relative sliding of the inner shaft part 14. Since a clearance is left after spline-fitting at a part of the shaft in the circumferential direction, the sliding resistance can be suppressed. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a telescopic shaft used for a vehicle steering system and the like.
[0002]
[Prior art]
Some of the above-mentioned telescopic shafts have an inner shaft portion and a hollow outer shaft portion, and these are spline-fitted to each other so as to be relatively slidable in the axial direction. A substantially annular fastening member is fitted on the outer periphery of the fitting portion of the outer shaft portion to be spline-fitted, and the outer shaft portion is tightened and contracted by the fastening member, eliminating the play between the outer shaft portion and the inner shaft portion. (See, for example, Patent Document 1).
[0003]
[Patent Document 1]
JP-A-11-105716
[Problems to be solved by the invention]
However, when the outer shaft portion is tightened by the above-described tightening member to remove play, the gap between the corresponding spline teeth is clogged in the entire circumferential direction of both shaft portions, so that the sliding at the time of relative sliding between both shaft portions is performed. Dynamic resistance tends to increase.
Conversely, if the tightening force is reduced to reduce the sliding resistance, play cannot be eliminated.
[0005]
Then, an object of the present invention is to solve the above-mentioned technical problem, and to provide a telescopic shaft capable of suppressing play of spline fitting and suppressing increase in sliding resistance.
[0006]
Means for Solving the Problems and Effects of the Invention
A telescopic shaft according to a first aspect of the present invention is a telescopic shaft formed by inserting an inner shaft portion having an axially formed male spline engaging with the female spline into a hollow outer shaft portion having an axially formed female spline. In the shaft, a plurality of plastically deformed portions formed on the outer shaft portion by local pressurization to the outer circumferential portion of the outer shaft portion and separated in the circumferential direction, and an outer circumferential portion of the outer shaft portion corresponding to these plastically deformed portions. A fastening member that is wound circumferentially around the predetermined portion and elastically urges the predetermined portion radially inward, and each of the plastically deformed portions is radially formed at a corresponding portion of the outer peripheral portion of the inner shaft portion. It is characterized in that it includes a contact engagement portion that makes contact engagement without play and allows relative sliding of the inner shaft portion.
[0007]
According to the present invention, the gap for spline fitting between the two shaft portions is removed only in a part of the circumferential direction (contact engaging portion) to eliminate radial play, while removing the contact engaging portion. Since the gap for the spline fitting is left in the remaining area in the circumferential direction, the sliding resistance of the two shaft portions during relative sliding does not increase.
A second invention is characterized in that, in the first invention, the fastening member is wound around a reduced diameter portion provided on an outer peripheral portion of the outer shaft portion. According to the present invention, since the reduced diameter portion contracts in the circumferential direction and easily bends in the radial direction, the plastic deformation portion can be effectively urged by tightening the tightening member, thereby suppressing play and reducing sliding resistance. Preferred for suppression.
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
An intermediate shaft as a telescopic shaft according to one embodiment of the present invention will be described. FIG. 1 is a schematic diagram showing a schematic configuration of a vehicle steering system provided with the above-described intermediate shaft.
Referring to FIG. 1, a vehicle steering system 1 has an intermediate shaft 2. The intermediate shaft 2 is also called an intermediate shaft. The intermediate shaft 2 applies a steering torque applied to the steering wheel 3 to steer a wheel (not shown), and a steering shaft connected to the steering wheel 3 at one end 4a. 4 to a steering mechanism 5 for steering the wheels.
[0009]
The vehicle steering device 1 includes a steering shaft 4 that transmits the above-described steering torque, and a steering column 6 that rotatably supports the steering shaft 4 through the inside thereof. The other end 4b of the steering shaft 4 is connected to the rotation shaft 9 of the steering mechanism 5 through a universal joint 7, the intermediate shaft 2, a universal joint 8, and the like. When the steering wheel 3 is steered, the steering torque is transmitted to the steering mechanism 5 via the steering shaft 4 and the like, whereby the wheels can be steered.
[0010]
The steering shaft 4 has an upper shaft 10 as an outer shaft connecting the steering wheel 3 to one end, and a lower shaft 11 as an inner shaft. The upper shaft 10 and the lower shaft 11 are connected to each other by a spline fitting structure so as to be relatively movable along the axial direction of the steering shaft 4 and to rotate integrally. The steering shaft 4 functions as an extendable and retractable shaft to adjust the position of the steering wheel 3 and to absorb the impact of a vehicle collision.
[0011]
Further, in the vehicle steering system 1, the steering column 6 is supported by the vehicle body 12 (only part of which is shown) so that the position can be adjusted, so that the position of the steering wheel 3 can be adjusted. With the position adjustment, the position of the other end 4b of the steering shaft 4 may change. Further, the position of the steering mechanism 5 may change. The intermediate shaft 2 is extendable and contractable so as to absorb such a change in position.
The intermediate shaft 2 has a hollow outer shaft portion 13 and an inner shaft portion 14, and is formed by inserting an end portion 14a of the inner shaft portion 14 into a fitting hole 13b of an end portion 13a of the outer shaft portion 13. . The axes of both shaft portions 13 and 14 coincide with the axis of intermediate shaft 2. Corresponding ends 13a, 14a of the two shafts 13, 14 are spline-fitted to each other so as to be relatively slidable in the axial direction S of the intermediate shaft 2. Both shaft portions 13 and 14 are made of a metal member such as steel.
[0012]
Please refer to FIG. 2 and FIG. A female spline 15 is formed in the inner peripheral portion 13c of the fitting hole 13b of the end portion 13a of the outer shaft portion 13 so as to extend in the axial direction S. The female spline 15 has a large number of spline teeth 15a (only a part is shown in FIG. 3) extending at a predetermined length in the axial direction S. The outer peripheral portion 13d of the end portion 13a of the outer shaft portion 13 has a small diameter reduced portion 13e having a predetermined width and a pair of large diameter portions 13f sandwiching the reduced diameter portion 13e in the axial direction S.
[0013]
A male spline 16 that engages with the female spline 15 is formed on the outer peripheral portion 14b of the end portion 14a of the inner shaft portion 14 so as to extend in the axial direction S thereof. The male spline 16 has a large number of spline teeth 16a (only some of which are shown in FIG. 3) extending at a predetermined length in the axial direction S. The two spline teeth 15a, 16a mesh with each other. The reduced diameter portion 13e is arranged such that the two spline teeth 15a, 16a always mesh inside the reduced diameter portion 13e.
[0014]
The intermediate shaft 2 includes a play suppressing unit 17 that suppresses play between the inner shaft portion 14 and the outer shaft portion 13 in the radial direction R. The play suppressing means 17 includes a plurality of, for example, three plastically deformed portions 18 (only some of which are shown in FIG. 2) formed on the outer shaft portion 13, and a tightening member 19 that tightens the plastically deformed portions 18. The fastening member 19 is fitted to a reduced diameter portion 13e as a predetermined portion of the outer peripheral portion 13d corresponding to the plastic deformation portion 18.
Referring to FIG. 3, the plurality of plastically deformed portions 18 are spaced apart from each other in the circumferential direction T of the intermediate shaft 2 and are arranged substantially uniformly. Each of the plastically deformed portions 18 is formed by, for example, locally pressing the outer peripheral portion 13d of the outer shaft portion 13 by a predetermined tool such as a caulking tool, and a concave portion extending in the axial direction S as a trace of the locally pressed portion. 18a is formed on the outer peripheral portion 13d, and the inner peripheral portion 13c corresponding to the plastically deformable portion 18, that is, the spline teeth 15a on the back surface of the concave portion 18a and the vicinity thereof is substantially formed between the plastically deformable portions 18 in the circumferential direction T. The portion 13g of the intermediate outer shaft portion 13 is deformed so as to protrude inward in the radial direction R by a predetermined amount from the spline teeth 15a. This predetermined amount is set to an amount substantially corresponding to the play in the radial direction R of the spline fitting.
[0015]
Each of the plastically deformed portions 18 has a contact engagement portion 18b that is engaged with a corresponding portion 14c as a contact engagement portion of the outer peripheral portion 14a of the corresponding inner shaft portion 14 in a contact state. The contact engagement portion 18b is composed of a portion of the inner peripheral portion 13c corresponding to the plastic deformation portion 18.
The fastening member 19 has a substantially cylindrical shape, for example, an arc-shaped cross section, and is made of an elastic member such as spring steel. The fastening member 19 is wound around the reduced-diameter portion 13e along the circumferential direction T, and is externally moved in the circumferential direction T. It is arranged so as to surround a half or more of the reduced diameter portion 13e as a predetermined portion of the shaft portion 13 and to urge the reduced diameter portion 13e, particularly the plastic deformation portion 18 from the outside in the radial direction R.
[0016]
Please refer to FIG. The dimension L1 corresponding to the inner diameter of the fastening member 19 in the natural state is formed smaller than the outer diameter L2 of the reduced diameter portion 13e by a predetermined amount (L1 <L2), and the fitting member 19 is fitted in the reduced diameter portion 13e. Due to the elastic repulsion force, the reduced diameter portion 13e can be elastically urged inward in the radial direction R. The fastening member 19 forms a slit 19 a extending in the axial direction S between the arc ends. The slit 19a is opened at the end in the axial direction S, and its width can be adjusted. By passing the reduced diameter portion 13e through the slit 19a with the width of the slit 19a elastically expanded, the fastening member 19 can be fitted into the reduced diameter portion 13e.
[0017]
The removal of play will be described with reference to FIGS. For example, in a state where the end 14a of the inner shaft portion 14 is fitted in the fitting hole 13b of the end portion 13a of the outer shaft portion 13, the diameter of the outer shaft portion 13 is reduced to such an extent that both spline teeth 15a and 16a are not crushed. The plastic deformation portion 18 is formed by slightly caulking 13e with a caulking tool (not shown). Thereby, most of the play of the spline fitting between the inner peripheral portion 13c and the outer peripheral portion 14a corresponding to the plastic deformation portion 18 is removed without the fastening member 19 being fitted. Thereafter, the fastening member 19 is attached. The tightening member 19 elastically urges the plastic deformation portion 18 inward in the radial direction R, so that there is a slight play between the inner peripheral portion 13c and the outer peripheral portion 14a corresponding to the remaining plastic deformation portion 18. Is removed, and the contact engaging portions 18b of the respective plastically deforming portions 18 are in contact with the corresponding portions 14c of the outer peripheral portion 14a of the inner shaft portion 14 without play in the radial direction, and are formed along the axial direction S. The relative sliding of the shaft 14 is allowed.
[0018]
As described above, in the embodiment of the present invention, referring to FIG. 3, the gap of the spline fitting between the two shaft portions 13 and 14 is removed only at the contact engagement portion 18 b corresponding to a partial region R <b> 1 in the circumferential direction T. To eliminate play in the radial direction R, while leaving a gap for spline fitting in the remaining region R2 in the circumferential direction T excluding the above-mentioned contact engaging portion 18b. The sliding resistance does not increase.
The reduced diameter portion 13e contracts in the circumferential direction T and easily deforms in the radial direction R of the intermediate shaft 2, so that the plastic deformation portion 18 in the reduced diameter portion 13e is directed toward the inner shaft portion 14 by tightening the tightening member 19. It can be effectively biased and is preferable for suppressing play and sliding resistance.
[0019]
Since the plastic deformation portion 18 and the fastening member 19 are used in combination, the amount of plastic deformation of the plastic deformation portion 18 can be suppressed, and variation in sliding resistance can be reduced.
Since the remaining slight gap of the spline fitting after the filling by the plastic deformation portion 18 is closed by the tightening of the tightening member 19, the tightening force of the tightening member 19 can be reduced, and a generally inexpensive elastic member having a small spring constant is used. Can also be used. In addition, the plastically deformed portion 18 can be formed by an inexpensive press working. Therefore, it is preferable to suppress play and sliding resistance at low cost.
[0020]
In the following, a modified example of the embodiment of the present invention will be described, and the description will be focused on the points different from the above-described embodiment.
For example, the large-diameter portion 13f on the shaft end side of the outer shaft portion 13 is omitted, and the reduced-diameter portion 13e is extended to the shaft end 13h of the outer shaft portion 13 and opened toward the shaft end 13h along the axial direction S. May be. In this case, the tightening member 19 can be easily mounted on the reduced diameter portion 13e from the opened shaft end while the amount of expansion of the slit 19a of the tightening member 19 is reduced.
[0021]
Alternatively, the end portion 13a of the outer shaft portion 13 may be formed to have a constant outer diameter in the axial direction S, and the fastening member 19 may be attached to the outer peripheral portion 13d corresponding to the plastic deformation portion 18 as a predetermined portion.
The number of the plastic deformation portions 18 may be two or four or more in the circumferential direction T of the intermediate shaft 2. It is also conceivable that the two shaft portions 13, 14 are fitted after the formation of the plastic deformation portion 18.
[0022]
Further, the present invention may be applied to a steering shaft 4 as a telescopic shaft with reference to FIG. 1, in which case the upper shaft 10 may be an inner shaft and the lower shaft 11 may be an outer shaft. . In addition, various changes can be made within the scope of the claims of the present invention.
[Brief description of the drawings]
FIG. 1 is a schematic view showing a schematic configuration of a vehicle steering system including an intermediate shaft as a telescopic shaft according to an embodiment of the present invention.
FIG. 2 is an exploded perspective view of a main part of the intermediate shaft of FIG.
FIG. 3 is a sectional view of a main part of the intermediate shaft shown in FIG.
[Explanation of symbols]
1 Intermediate shaft (extensible shaft)
4 Steering shaft (stretchable shaft)
10 Upper shaft (outer shaft)
11 Lower shaft (inner shaft)
13 outer shaft portion 13c inner circumferential portion of outer shaft portion 13d outer circumferential portion 13e outer shaft portion reduced diameter portion (predetermined portion of outer circumferential portion of outer shaft portion)
14 inner shaft portion 14b outer circumferential portion 14c of inner shaft portion corresponding portion 15 of outer circumferential portion of inner shaft portion 15 female spline 16 male spline 18 plastic deformation portion 18b contact engagement portion of plastic deformation portion 19 fastening member R radial direction S axial direction T Circumferential direction

Claims (2)

In a telescopic shaft, a female spline is formed in an axially formed hollow outer shaft portion, and a male spline engaged with the female spline is inserted in an axially formed inner shaft portion.
A plurality of plastically deformed portions formed on the outer shaft portion by local pressurization on the outer peripheral portion of the outer shaft portion and separated in the circumferential direction,
A fastening member that is circumferentially wound around a predetermined portion of the outer peripheral portion of the outer shaft portion corresponding to these plastically deformed portions and elastically urges the predetermined portion radially inward,
Each plastically deformable portion includes a contact engagement portion that radially contacts and contacts a corresponding portion of the outer peripheral portion of the inner shaft portion without play and allows relative sliding of the inner shaft portion. shaft. The telescopic shaft according to claim 1, wherein the fastening member is wound around a reduced diameter portion provided on an outer peripheral portion of an outer shaft portion.

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