JPS5981253A - Shock absorbing steering shaft - Google Patents

Abstract

PURPOSE:To absorb shock energy by making use of the shear strength of a binder and the friction resistance of a fitting part by coupling both connection ends together via said binder. CONSTITUTION:When a shock absorbing steering shaft 10 comprising a upper shaft and a lower shaft made of a composite material is used as a shock absorbing member, the binder 16 of a fitting part between a upper shaft 11 and a lower shaft 12 is subjected to shear failure caused by axial force, and thus the primary shock energy is absorbed. Then, edges of respective tooth parts of a spline and their ridges of the lower shaft 12 enters the upper shaft while cutting the absorbing material 16 arranged on the expanded diameter part of the upper shaft 11, thereby allowing the shock energy to be absorbed. Further, tightening force is produced due to the hardening and contraction of the binder, and frictional resistance is yielded during shaft penetration, allowing a smooth energy absorption curve to be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a shock absorbing steering shaft for a motor vehicle.

BACKGROUND OF THE INVENTION Conventionally, a shock-absorbing steering shaft for an automobile as shown in FIG. 1 has been known. In FIG. 1 showing this conventional shock-absorbing steering shaft and FIG. 2 showing a fragmentary enlarged portion of the shaft, 1 is a lower tube, 2 is an upper tube, and 3 is a steel rod. 1 and a steel sole inserted into the fitting portion of the upper tube 2, 4 a lower shaft, 5 an upper shaft, and 6 a steering wheel, respectively.

According to the conventional shock-absorbing steering shaft with such a structure, when the steel part 3 is inserted into the fitting part of the lower tube 1 and the upper tube 2, when the entire column receives an axial force, the steel part 3 slides against each other and the tubes It rolls while creating grooves on the surface, and this resistance absorbs energy. The lower shaft 4 and upper shaft 5 are fitted in the same way as tubes, but in order to mainly transmit torque, they are formed with a cross-sectional shape that approximates an ellipse in the direction of rotation, and when subjected to axial force, this fitting The section was designed to slide axially without resistance.

However, in the conventional shock-absorbing steering shaft as described above, the inner and outer tubes, in which a portion of steel is inserted, must be manufactured with very high precision as well as part of the diameter, resulting in a very high cost. The disadvantage was that it was expensive. Furthermore, since the conventional shock-absorbing steering shaft was entirely made of steel, the weight of the entire shaft was heavy, and even a light shaft weighed more than 3Kp excluding the wheels. For these reasons, it has been desired that the conventional ttS absorbing steering shaft be further improved for the purpose of automobile manufacturing, construction, and weight reduction.

Accordingly, an object of the present invention is to provide a shock-absorbing steering shaft that is lightweight and has good energy absorption properties while reducing manufacturing costs.

Hereinafter, the shock-absorbing steering shaft of the present invention will be explained in more detail with reference to preferred embodiments shown in the accompanying drawings.

FIG. 3 shows an embodiment of the shock absorbing steering shaft of the present invention. The steering shaft 10 of this embodiment includes a hollow upper shaft 11 and a lower shaft 12 made of a composite material made of carbon fiber reinforced plastic, for example.

A steering wheel 13 and a steering column 14 are attached to one end of the upper shaft 11, and one end of a lower shaft 12 is fitted inside the other end, so that the two are connected on one axis. The other end of the lower shaft 12 is connected via a universal joint 15 to a suitable steering mechanism (not shown).

At the fitting portion between the upper shaft 11 and the lower shaft 12, the outer shape of the connecting end of the lower shaft 12 is splined, and the connecting end of the upper shaft 11 has each spline toothed portion of the lower shaft 12. It is formed into a polygonal shape that corresponds to the corner. Such a fitting connection between the upper shaft 11 and the lower shaft 12 is achieved by attaching the upper shaft 1 to the connecting end of the lower shaft 12, which has a splined outer shape.
This can be done by directly winding 1. At this time, that is, when the upper shaft 11 and the lower shaft 12 are fitted together as described above, a bonding agent 16 is disposed between each tooth portion of the spline and the inner surface of the upper shaft 11.

In the upper shaft 11 that is fitted and connected to the lower shaft 12 as described above, a diameter-enlarging portion 17 is formed from the portion where the end edge of the lower shaft 12 is located toward the steering handle 13 side. There is. An absorbent material 18, such as a sintered engineering plastic body, is fitted inside the enlarged diameter portion 17. The edge of each toothed portion of the spline is in contact with a part of the edge of the absorbent material 18, as shown in FIG. Such an absorbent material 18 allows the lower shaft 12 to pass through the upper shaft 11 after the binder 16 is sheared.
It acts to generate a certain resistance on the spline of the lower shaft 12 when it enters the interior.

A shock absorbing steering shaft 10 consisting of an upper shaft and a lower shaft made of composite material as described above.
According to , when an axial force (impact compressive load) is applied, the bonding agent 16 at the fitting part between the upper shaft 11 and the lower shaft 12
causes shear failure and the first 41jl impact energy is absorbed. Next, the lower shaft 12 has an end edge of each tooth portion of the spline and a peak portion thereof aligned with the upper shaft 11.
It enters the upper shaft while cutting off the absorbent material 16 disposed in the enlarged diameter part of the upper shaft, thereby absorbing energy.

Since the upper shaft 11 is directly wrapped around the splined portion of the lower shaft 12, a tightening force is generated due to hardening and shrinkage, and frictional resistance acts upon entry, making it possible to obtain a smooth energy absorption curve. In addition, absorbent material 1
8 is made of a brittle and highly rigid material, such as shiboripropylene with micro balloons, and even after receiving impact energy, the spline parts are engaged, so that the transmission torque can still be transmitted, and as a result, for example, In order to avoid traffic confusion due to a vehicle collision, it is possible to enable steering of the steering wheel even after the collision.

According to an impact energy absorption test using such an example, it was confirmed that a maximum reaction force of 500 K9 was sufficiently absorbed. For your reference, please refer to the US Safety Standards (MVSS 2).
03), the reaction force on the human body is 1135 K.
Therefore, the shock absorbing steering shaft of the above embodiment fully satisfies this standard.

In the embodiments described above, the lower shaft was splined, but the upper shaft may be splined, and the lower shaft may be wrapped. Also,
Instead of spline processing, serration processing including indelyu serrations may be used.

As explained above, according to the present invention, the impact absorption function is effectively used to effectively utilize the stable and low interlaminar shear strength (corresponding to the binder here) of the composite material, and also to reduce shrinkage due to thermosetting of the plastic. Stable M by using
Obtains wire resistance, allows smooth energy absorption,
In addition, since the fibers between the teeth of the spline are formed straight, torque can be transmitted reliably, and the spline can be manufactured lightweight and inexpensively.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view schematically showing a conventional steel impact-absorbing steering shaft, Figure 2 is a fragmentary cross-sectional view showing a part of the conventional impact steering shaft shown in Figure 1, and Figure 3. 4 is a partially cutaway front view of a shock-absorbing steering shaft according to an embodiment of the present invention, FIG. 4 is a sectional view of the embodiment taken along line IV-IV in FIG. 3, and FIG. FIG. 5 is a partial cross-sectional view taken along the line ■-■ in FIG. 4; 10...Shock absorbing steering shaft, 11...
Upper shaft, 12... Lower shaft, 16.
... Binder, 17 ... Expanded diameter section, 18 ... Absorbent material. Note that the same reference numerals in the figures indicate the same or equivalent parts. Agent Shin Kuzuno - Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 11 17

Claims (1)

[Claims] A shock-absorbing steering shaft formed by fitting and connecting an upper shaft and a lower shaft formed of a composite material, wherein the outer shape of the connecting end of either the upper or the lower shaft is provided with splines or serrations, The connecting end is fitted to the other end of either the upper or lower shaft via a binder, and impact energy is absorbed by the shear strength of the binder and the frictional resistance of the fitted part. Shock-absorbing steering shaft.