JPH0310964A - Steering column tube of automobile - Google Patents

Abstract

PURPOSE:To improve energy absorbing effect by forming a buckling adjustment portion one part of the inside piece of which is bent toward an outside piece side, on an energy absorbing plate disposed between the lower member and the upper member of a steering column tube. CONSTITUTION:A steering column tube 11 is formed by a lower member one part of which is fixed to a car body, an upper member 13 having a pipe diameter larger than that of the lower member 12, and a plurality of energy absorbing plates 14 disposed therebetween. In this case, a first buckling adjustment portion 15 one of which is brought in contact with an outside piece 14c welded to the lower end face of the upper member 13 is arranged on the inside piece 14b welded to the outer circumference of the lower member 12 at the energy absorbing plate 14. A second buckling adjustment portion 16 is arranged on the outside piece 14c so that one part near an outward curve portion 14a disposed in the lower end portion of the upper member 13 may touch the inside piece 14b.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a steering column tube for an automobile, and more particularly to an improvement in an energy absorbing structure during a vehicle collision.

(Prior Art) In an automobile collision, the driver may be thrown forward by the inertia of the automobile's running speed, and his or her chest may be severely bruised by the steering wheel.

Therefore, a steering column tube has been developed in which the steering column tube is compressed and deformed in the axial direction to absorb the impact force that acts on the driver when the driver slams into the steering wheel due to a collision. ing.

FIG. 10 is a sectional view showing a proposed example of the steering column tube 1 having the above-mentioned energy absorption function.

As shown in the figure, this steering column tube 1
consists of a column tube lower member 2 fixed to the vehicle body, a column tube upper member 3 whose lower end is slidably fitted onto the upper end of the column tube lower member 2, and both members 2,
3 and a plurality of energy absorbing plates 4 arranged along the circumferential direction.

The energy absorbing plate 4 is provided with a U-shaped outwardly bent portion 4a which is bent such that one end thereof is bent outward. And the outward curved portion 4
a are located within the lower end of the column tube upper member 3, and the tips of the long inner pieces 4b are fixed to the outer peripheral surface of the upper end of the column tube lower member 2, and the short outer pieces 4C are fixed to the lower end of the column tube upper member 3, respectively. Although not shown, this steering column tube 1
A steering shaft having a steering handle at its upper end is inserted through the inside, and its lower end is inserted into the steering gear box. When the driver's body collides with the steering wheel during a car collision and an impact force of more than a predetermined value is applied to the column tube upper member 3, the column tube upper member 3 is pushed forward as shown by the arrow P and inward. The piece 4b is successively buckled so as to be pushed outward from the vicinity of the outwardly bent portion 4a toward the tip side, and the impact energy is absorbed by being replaced by the work of the buckling. It is composed of

Next, the relationship between the load and the amount of displacement of the steering column tube 1 during the collision energy absorption process will be considered.

Figure 11 shows the load W on the steering column tube 1.
- A graph showing the characteristics of the displacement amount X, in which the vertical axis shows the load W acting on the steering column tube 1, and the horizontal axis shows the axial displacement amount X (
stroke).

Therefore, the amount of energy absorbed by the steering column tube 1 is given by the area surrounded by the characteristic curve in FIG. 11 and the X-axis. FIG. 12 shows the deformed state of the energy absorbing plate 4 corresponding to point A in FIG. 11, FIG. 13 shows the deformed state corresponding to point B, and FIG.
The deformation states corresponding to the points are shown respectively.

As shown in FIG. 11, when each energy absorbing plate 4 receives an impact force from the column tube upper member 3, it starts to initially buckle under a load W1. This initial buckling is caused by the energy absorbing plate 4 as shown in FIG.
A part of the inner piece 4b is pushed outward and deformed into a curve so as to come into contact with the outer piece 4C, and this buckling causes the steering column tube 1 to be displaced by a displacement amount X1.

When a further load is applied, secondary buckling occurs under load W2. This secondary buckling occurs in the outer piece 4 as shown in FIG.
The vicinity of the outwardly bent portion 4a of C is deformed so as to curve toward the inner piece 4b, and due to this buckling, the steering column tube 1 is displaced by a displacement amount X2. In this way, when the load reaches W3, the inner piece 4b starts to buckle continuously from the vicinity of the outwardly bent portion 4a toward the tip side, and from then on, by continuing to apply a load approximately equal to the load W3, the inner piece 4b continuously buckles. The bending progresses, and the amount of displacement reaches X3 as shown in FIGS. 11 and 14.

(Problem to be Solved by the Invention) By the way, considering the protection of occupants in the event of a vehicle collision, it is desirable that the amount of energy absorbed due to the deformation of the steering column tube 1 is as large as possible. This is achieved by setting a large load W or displacement amount X that is involved in one displacement. However, the upper limit of the acceleration of the displacement when the steering column duplex 1 is displaced is limited to prevent an excessive load from acting on the occupant, and the amount of displacement X is also within a predetermined range due to vehicle design requirements. Limited. Therefore, in developing the energy absorption structure of the steering column tube 1, it is necessary to devise ways to maximize the amount of energy absorption within the above-mentioned limited load W and displacement amount X.

However, in the conventional energy absorption structure of the steering column tube 1, as shown in FIGS. 11 to 14, initial buckling and secondary buckling occur in the energy absorption plate 4, so the load at the start of buckling ( There was a problem in that Wl, W2) was smaller than the load W3 during subsequent continuous buckling, and the amount of energy absorption was reduced by that amount.

(Objective of the Invention) The object of the present invention is to solve the problems of the prior art described above and to provide a steering column tube for an automobile that can obtain a large amount of energy absorption under a limited load and displacement. .

(Means for Achieving the Object) The present invention has a structure in which the lower end of a column tube upper member is slidably fitted onto the upper end of a column tube lower member fixed to a vehicle body, and the lower end of a column tube upper member is slidably fitted to the outer end of a column tube lower member fixed to a vehicle body. A plurality of energy absorption plates each having a curved portion are disposed along the circumferential direction between the column tube lower member and the column tube upper member, and the outward curved portion is disposed within the lower end portion of the column tube upper member. A steering column tube for an automobile, wherein one inner end of the energy absorbing plate is fixed to the upper end of the column tube lower member, and one outer end of the energy absorbing plate is fixed to the lower end of the column tube upper member. In order to achieve the above object, a part of the inner piece is curved and deformed toward the outer piece to form a buckling adjustment part within the lower end of the column tube upper member.

(Embodiment) Fig. 1 is a side sectional view showing a steering column tube 11 for an automobile which is a first embodiment of the present invention, Fig. 2 is a sectional view taken along the line ■-■ in Fig. 1, and Fig. 3 is a sectional view thereof. FIG. 2 is a schematic side view showing a steering device to which a steering column tube 11 is applied. As shown in these figures, the steering column tube 11 includes a column tube lower member 12 partially fixed to the vehicle body 10, a column tube upper member 13 having a larger diameter than the column tube lower member 12, and a column tube upper member 13 having a larger diameter than the column tube lower member 12. It consists of a plurality of energy absorbing plates 14 arranged between members 12,13. A lower end portion of a column tube upper member 13 is fitted onto the upper end portion of the column tube lower member 12 so as to be slidable along the tube axis direction. Furthermore, a guide portion 12a whose upper end is finished with a large diameter is formed at the upper end of the column tube lower member 12, and the entire outer peripheral surface of the guide portion 12a can freely slide on the inner peripheral surface of the column tube upper member 13. When the column tube upper member 13 slides, it is configured to be accurately guided in the tube axis direction.

Further, three energy absorbing plates 14 are arranged at equal intervals along the circumferential direction between the column tube lower member 12 and the column tube upper member 13. Each of the energy absorbing plates 14 is formed with a U-shaped outwardly bent portion 14a having one end bent outwardly. And the outward curved portion 14a
are respectively located within the lower end of the column tube upper member 13, the tips of the long inner pieces 14b are welded to the outer peripheral surface of the column tube lower member 12, and the tips of the short outer pieces 14c are They are each welded to the lower end surface of the column tube upper member 13. Further, the inner piece 14b is provided with a first buckling adjustment part 15 which is curved and deformed toward the outer piece 14c so that a part thereof comes into contact with the outer piece 14c,
The outer piece 14c is provided with a second buckling adjustment portion 16 that is curved toward the inner piece 14b so that the vicinity of the outwardly bent portion 14a contacts the inner piece 14b. Further, as shown in FIG. 3, a steering shaft 10b having a steering handle 10a at its upper end is inserted through the steering column tube 11, and its lower end is inserted into a steering gear box (not shown). .

By the way, the first and second buckling adjustment parts 15 and 16 are as follows.
It is formed as follows. That is, as shown in FIGS. 4 to 6, the first and second buckling adjustment parts 15
．． The tips of the long pieces 24b that will constitute the inner piece 14b of the three energy absorbing plate constituent members 24 that are not provided with the inner piece 16 are welded to a predetermined position of the column tube lower member 12, and the outer piece 14
The tips of the short pieces 24c that will constitute the column tube c are respectively welded to predetermined positions on the column tube upper member 13. Thereafter, the burr compression is forcibly performed so that the column tube upper member 13 slides a predetermined amount toward the column tube lower member 12. As a result, a deformation similar to the conventional initial buckling shown in FIG. A deformation similar to the secondary buckling occurs in the energy absorbing plate component 24 to form the second buckling adjustment portion 16.

Note that the steering column tube 11 is assembled to the vehicle body 10 after the first and second buckling adjustment portions 15 and 16 are formed by the above-mentioned buckling compression.

According to this steering column tube 11, the first and second buckling adjustment parts 1 are arranged so as to correspond to the conventional initial buckling and secondary buckling shown in FIGS. 12 and 13.
5.16 is pre-formed on the energy absorbing plate 4, so that the steering handle 10 is
When the driver's body hits point a and the column tube upper member 13 is pushed in the direction shown by the arrow P in FIGS. 1 and 3, the load-displacement characteristic graph of the steering column tube 11 in FIG. As shown in FIG. 2, the buckling immediately shifts to continuous buckling under the load w3 without causing initial buckling or secondary buckling, and thus the outwardly bent portion 14b forms the inner piece 14b.
, and finally reaches the displacement amount X3. The impact energy is absorbed by the work of continuous buckling. In this case, since the displacement of the steering column tube 11 is entirely due to continuous buckling, the load W during the displacement period is kept almost constant. Therefore, energy can be effectively absorbed even at the beginning of buckling,
Even with a limited load W and displacement amount X, a very large and best energy absorption amount can be obtained.

FIG. 8 is a sectional view showing an energy absorbing plate 34 applied to a steering column tube 31 according to a second embodiment of the present invention. As shown in the figure, this second
The steering column tube 31 of the embodiment shown in FIG.
The difference from the steering column tube 11 of the above embodiment is that the first and second buckling adjustment parts 15 and 16 of the steering column tube 11 are formed by compression, whereas this energy absorption plate The buckling adjustment portion 35 of 34 is formed by burr molding.

That is, in a state where the energy absorption plate 34 is not attached to the column tube lower member 32 and the column tube upper member 33, the outer piece 34 of the inner piece 34b
A buckling adjustment portion 35 in which a region corresponding to c is curved toward the outer piece 34c and extends to the vicinity of the outwardly bent portion 34a.
is formed. Then, the energy absorbing plate 34 on which the buckling adjustment portion 35 is formed is attached to the column tube lower member 32 and the column tube upper member 33 in the same manner as the steering column tube 11 of the first embodiment. The rest of the structure is the same as the steering column tube 11 of the first embodiment.

According to this steering column tube 31, since the buckling adjustment portion 35 is formed in advance on the energy absorbing plate 34, substantially the same effect as the steering column tube 11 of the first embodiment can be achieved. Furthermore, since the buckling adjustment portion 35 is formed by burr molding, there is no need to consider deformation of the longitudinal dimension of the steering column tube 11 due to burr compression as in the first embodiment. The design of the steering column tube 13 becomes easier.

In the first and second embodiments, the upper end of the column tube lower member 12 is finished to have a large diameter to form the guide portion 12a so that the column tube upper member 13 can slide smoothly. However, the guide portion 12a is not limited to this. For example, as shown in FIG. 9, a part of the upper end of the column tube lower member 12 may be finished to have a large diameter to form a bead-shaped guide portion 12b. A generally cylindrical spacer collar may be fixed to the outer periphery of the upper end of the column tube 12, and the outer periphery of the spacer collar may be slidably brought into contact with the inner periphery of the column tube upper portion 13.

(Effects of the Invention) As described above, according to the steering column tube of the present invention, the energy absorbing plate disposed between the column tube lower member and the column tube upper member has a portion of the inner piece of the energy absorbing plate disposed between the column tube lower member and the outer column tube member. Since the buckling adjustment part is curved toward the upper part of the column tube, when an impact force is applied to the column tube upper member due to a vehicle collision, etc., it immediately transitions to continuous buckling, minimizing the load and displacement. The effect is that a very large amount of energy absorption can be obtained.

[Brief explanation of the drawing]

Fig. 1 is a side sectional view showing a steering column tube according to a first embodiment of the present invention, and Fig. 2 is a cross-sectional view of the steering column tube shown in Fig.
3 is a schematic side view showing a steering device to which the steering column tube is applied; FIG. 4 is a plan view showing an energy absorption plate component applied to the first embodiment; FIG. The figure is a side view, FIG. 6 is a front view, FIG. 7 is a graph showing the load-displacement characteristics of the steering column tube of the first embodiment, and FIG. 8 is a graph of the second embodiment of the present invention. Side view showing the energy absorbing plate applied to the steering column tube of
Fig. 9 is a sectional view showing a modified example of the steering column tube of this embodiment, Fig. 10 is a sectional view showing a conventional steering column tube, and Fig. 119 shows the load-displacement characteristics of the conventional steering column tube. The graphs shown in FIGS. 12 to 14 are side views showing the deformed state of the energy absorbing plate at a predetermined point in FIG. 11, respectively. 11.31...Steering column tube, 12.
32...Column tube lower member, 13.33...
Column tube upper member, 14.34...Energy absorption plate, 14a, 34a...Outward bent portion, 14b, 34b...Inner piece, 14c, 34c...Outer piece, 15...No. 1 buckling adjustment section, 16... second buckling adjustment section, 35... buckling adjustment section Fig. 3

Claims (1)

[Claims] (1) The lower end of the column tube upper member is slidably fitted onto the upper end of the column tube lower member fixed to the vehicle body, and an energy absorption plate having an outwardly bent portion with a substantially U-shaped cross section is provided. A plurality of energy absorbing plates are arranged along the circumferential direction between the column tube lower member and the column tube upper member, and the outwardly bent portion is located within the lower end of the column tube upper member. In a steering column tube for an automobile, one inner end of the column tube is fixed to the upper end of the column tube lower member, and one outer end of the steering column tube is fixed to the lower end of the column tube upper member, the inside of the lower end of the column tube upper member. A steering column tube for an automobile, characterized in that a part of the inner piece is curved and deformed toward the outer piece to form a buckling adjustment part.