JPH11124049A - Tie rod structure of steering device for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make a fuse portion of a tie rod work in the same way whether the axial load applied to the tie rod is a compressive load or tensile load. SOLUTION: A tie rod 10 having a fuse portion, (i.e., a portion that absorbs and reduces excessive load in the axial direction) in the center, of which the fuse portion is configured by an extrapolated shaft 11, an interpolated shaft 12 that is fit so that it can move in the axial direction within the extrapolated shaft 11, and a connecting means 14 that connects the interpolated shaft 12 and the extrapolated shaft 11. The tie rod is configured so that when a load in the axial direction exceeding the set value is applied to either the extrapolated shaft 11 or the interpolated shaft 12, the connection by the connecting means 14 is released, and the interpolated shaft 12 moves relative to the axial direction against the extrapolated shaft 11.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tie rod structure for a vehicle steering system, and more particularly to a tie rod structure having a fuse portion (a portion for absorbing and reducing axial overload) in an intermediate portion.

[0002]

2. Description of the Related Art A tie rod structure of this type is disclosed, for example, in Japanese Utility Model Laid-Open Publication No. 7-37862. In this tie rod structure, a portion of the tie rod is made smaller in diameter than a general shaft portion so that a fuse portion is formed. When a tie rod is subjected to an axially excessive compressive load (compressive load equal to or greater than a set value), bending deformation occurs at the fuse portion, and the bending deformation causes a change from the wheel side to the gear box side. The transmission of the excessive compression load is absorbed and reduced.

[0003]

In the tie rod structure disclosed in the above publication, the fuse portion functions properly for a compressive load but does not function properly for a tensile load. If an excessive tensile load is transmitted to the gear box, the gear box may be damaged.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-described problem. In a tie rod having a fuse portion at an intermediate portion, the fuse portion includes an extraneous shaft, and an extraneous shaft. An insertion shaft fitted movably in the axial direction therein, and a connecting means for connecting the insertion shaft and the extrapolation shaft, and an axis not less than a set value on the extrapolation shaft or the interpolation shaft. When an directional load is applied, the connection by the connection means is released, and the insertion shaft is relatively moved in the axial direction with respect to the external shaft. In this case, it is preferable that a rubber layer is interposed at a fitting portion between the extraneous shaft and the extraneous shaft, and that the extraneous shaft is formed of a hollow pipe.

[0005]

In the tie rod structure of the vehicle steering system according to the present invention, when an axial load greater than the set value is applied to the tie rod by an external force applied to the wheel side, the set value is applied to the extrapolated shaft or the interpolated shaft. Is applied, the connection by the connecting means is released, and the insertion shaft relatively moves in the axial direction with respect to the external shaft. By the way, since such an operation can be similarly obtained regardless of whether the axial load acting on the tie rod is a compressive load or a tensile load, an excessive compressive load or a tensile load is not transmitted from the wheel side to the gear box side. The gear box is not damaged by any external force applied to the wheel.

Further, when a rubber layer is interposed at the fitting portion between the outer shaft and the inner shaft in the practice of the present invention, flutter, kickback and the like can be effectively reduced by the rubber layer. it can. When the extrapolation shaft is formed of a hollow pipe, the weight of the tie rod can be reduced.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. A tie rod 10 according to the present invention shown in FIG.
And a cylindrical rubber layer 1 on the left end of the extrapolation shaft 11 in the figure.
3 and a lock nut which is screwed to the right end of the external insertion shaft 11 in the drawing and is connected to the external insertion shaft 11 by the caulking connection means 14 so as to be movable in the axial direction. A tie rod end ball joint 16 fixed by 15 is connected to a rack bar (not shown) at the left end of the insertion shaft 12 in the figure, and a knuckle arm (not shown) at the tie rod end ball joint 16. The fuse portion A, which is a portion that absorbs and reduces an overload in the axial direction, is constituted by an outer shaft 11, an inner shaft 12, a rubber layer 13, and a caulking connection means 14. .

The extrapolated shaft 11 has a large diameter portion 1 having a predetermined length L.
1a, and tapered portions 11b and 11c are formed at both ends of the large diameter portion 11a. Interpolation shaft 12
Has a ball portion 12a at the left end in the drawing and a stopper portion 12b at the right end in the drawing.
And a socket (not shown) attached to the end of a rack bar (not shown) constitutes a rack end ball joint. The stopper portion 12b makes a stroke of a set amount S in the axial direction to thereby form the outer insertion shaft 11.
Abuts on the tapered portions 11b and 11c of the
The relative movement in the axial direction with respect to 1 is restricted. Further, an annular groove 12c for increasing the connection strength of the caulking connection means 14 is formed in an intermediate portion of the insertion shaft 12.

The rubber layer 13 is interposed in a state where the rubber layer 13 is compressed by a predetermined amount at a fitting portion between the outer insertion shaft 11 and the inner insertion shaft 12, and closely adheres to the inner periphery of the outer insertion shaft 11 at its outer periphery. At the same time, the inner circumference is in close contact with the outer circumference of the insertion shaft 12. The caulking connection means 14 is formed by caulking the entire circumference or a part of the outer shaft 11 corresponding to the annular groove 12c of the inner shaft 12 toward the annular groove 12c. When an axial load equal to or more than the set value is applied to the shaft 12, the connection between the outer shaft 11 and the inner shaft 12 is released to allow relative movement of the outer shaft 11 and the inner shaft 12 in the axial direction. Has become. The axial load (set value) at which the extrapolated shaft 11 and the interpolated shaft 12 start relative movement in the axial direction is determined by applying the extrapolated shaft 11 to the interpolated shaft 1.
It can be easily changed as appropriate by changing the depth of crimping into the 2 and the length in the circumferential direction.

In the tie rod 10 of the present embodiment configured as described above, when an external load applied to the tie rod 10 by an external force applied to the wheel side (knuckle arm side) exceeds a set value, the set value is applied to the outer shaft 11. The above axial load is applied, the connection by the caulking connection means 14 is released, and the insertion shaft 12 moves relative to the external shaft 11 in the axial direction. The relative movement between the outer shaft 11 and the inner shaft 12 is such that the stopper 12b of the inner shaft 12 is tapered by the taper portions 11b, 11c of the outer shaft 11.
Is regulated by contact with

By the way, the above operation (external shaft 1)
1 and the interpolation shaft 12)
The same applies if the axial load acting on the wheel is a compressive load or a tensile load, so that an excessive compressive or tensile load is applied from the wheel side (knuckle arm side) to the gear box side (rack bar side). And the gear box (the meshing portion between the rack and the pinion (not shown)) is not damaged by any external force applied to the wheel side. Even after the external shaft 11 and the internal shaft 12 have relatively moved, the steering force is still reduced by the frictional sliding resistance generated between the rubber layer 13 held by the external shaft 11 and the outer periphery of the internal shaft 12. Can be transmitted.

Further, in the tie rod 10 of the present embodiment, since the rubber layer 13 is interposed at the fitting portion between the outer shaft 11 and the inner shaft 12, flutter, kickback and the like are prevented by the rubber layer 13. It can be reduced effectively. In addition, since the outer shaft 11 is formed of a hollow pipe, the weight of the tie rod 10 can be reduced.

In the above embodiment, the tie rod 10
Of the fuse portion A of the external shaft 11 and the internal shaft 1
2, the present invention is implemented by being constituted by the rubber layer 13 and the caulking connection means 14. However, the fuse portion of the tie rod is connected to the external shaft, the internal shaft and the caulking connection means (the external shaft and the internal shaft are directly caulked. It is also possible to implement the present invention with a configuration using a connecting means).

In the above embodiment, the present invention is implemented by connecting the outer shaft 11 to the knuckle arm at the right end in the drawing and connecting the inner shaft 12 to the rack bar at the left end in the drawing. However, the configuration of both ends of the tie rod 10 is reversed left and right, and connected to the rack bar at the right end of the extrapolation shaft 11 in the drawing,
It is also possible to implement the present invention by being configured to be connected to the knuckle arm at the left end of the insertion shaft 12 in the drawing.

In the above-described embodiment, the caulking connection means is used as a connection means for disconnecting the shafts 11 and 12 when an axial load greater than a set value is applied to the external shaft 11 or the internal shaft 12. Although 14 is employed, the present invention can be implemented by employing other connecting means.

[Brief description of the drawings]

FIG. 1 is a partially cutaway front view showing an embodiment of the present invention.

[Explanation of symbols]

10 tie rod, 11 extrapolated shaft, 11a large diameter portion, 11b, 11c tapered portion, 12 internal shaft,
12a: ball portion, 12b: stopper portion, 12c: annular groove, 13: rubber layer, 14: caulking connection means.

Claims (3)

[Claims] 1. A tie rod having a fuse portion at an intermediate portion, wherein the fuse portion is connected to an externally inserted shaft, an internally inserted shaft movably fitted in the externally inserted shaft in an axial direction, and the internally inserted shaft. And a connecting means for connecting the extrapolating shaft and the extrapolating shaft, the coupling by the coupling means is released when an axial load of a set value or more is applied to the extrapolating shaft or the interpolating shaft, and the A tie rod structure for a vehicle steering system, wherein the insertion shaft is configured to relatively move in the axial direction. 2. A rubber layer is interposed at a fitting portion between the external insertion shaft and the internal insertion shaft.
A tie rod structure for the vehicle steering system according to the above. 3. The tie rod structure for a vehicle steering system according to claim 1, wherein the extrapolation shaft is formed by a hollow pipe.