JP2011161959A - Energy absorbing steering column - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inexpensive energy absorbing steering column in which a shrinkable movement starting load of a steering column during collision of a vehicle and a movement load during shrinkable movement are easily controlled. <P>SOLUTION: The energy absorbing steering column includes an outer tube 10, and an inner tube 20 arranged to be shrunk toward the inner side of the outer tube 10 by impact. An initial resistance rib 21a for controlling a movement starting load required for starting the relative shrinkable movement during the impact and a movement resistance rib 22 for controlling a movement load required for the relative shrinkage which is lower than the movement starting load are provided between the outer periphery of the inner tube 20 and the outer tube 10. The initial resistance rib 21a is a pressed-in portion where the inner tube 20 is pressed in the inner side of the outer tube 10, and the movement resistance rib 22 has a predetermined length in the axial direction of the outer periphery of the inner tube 20 to interfere with an opening end of the outer tube 10. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a steering column that absorbs impact energy applied to a steering shaft during a vehicle collision or the like.

2. Description of the Related Art A technique for reducing the impact of personnel on a steering wheel by adopting a steering column that can shrink in the axial direction while rotatably supporting a steering shaft is known.
As shown in FIG. 11, the impact energy absorption characteristics applied to the steering column are as follows. As shown in FIG. 11, the steering column begins to contract at a movement start load f ₀ at which contraction starts and a load f ₁ lower than that starts. In many cases, two types of characteristics that absorb energy by the product of force and movement amount (movement stroke) are required.
Therefore, it is desirable that the energy absorption column has a structure capable of controlling the setting range F ₀ of the movement start load for contraction and the setting range F ₁ of the movement load during contraction movement.

For example, Patent Document 1 discloses a structure in which a rib that is plastically deformed by movement of an inner tube is added to the inner side of the outer tube in a steering column including an outer tube and an inner tube fitted inside the outer tube.
However, the rib disclosed in the publication is for controlling the moving load, and a mechanism for controlling the movement starting load is additionally required.
In Patent Document 2, in a double tube structure of an inner tube and an outer tube, a movement start load is controlled by interposing a metal elastic bush at the press-fitting portion of both, and a separately provided plate is bent and moved. A technique for controlling a moving load is disclosed.
However, since the technology disclosed in the publication controls the moving load by the iron that the plate spring-like plate is bent and moved, a guide part that guides this movement is required, so the structure is complicated and the steering column is made compact. Is not only difficult, but also expensive.
Patent Document 3 discloses a structure in which a conical component member is coaxially arranged inside the passenger compartment of a column tube, and the conical component member absorbs energy in the process of opening the column tube into a tulip shape.
This technique controls the moving load, and cannot sufficiently control the moving start load.

JP 2004-249664 A JP 2007-168869 A JP-A-10-217980

  An object of the present invention is to provide an energy absorbing steering column that has a simple structure and can easily control the steering column shrinkage movement start load at the time of a vehicle collision and the movement load during the shrinkage movement and is inexpensive.

The energy absorption steering column according to the present invention includes an outer tube and an inner tube arranged to move and contract by impact inside the outer tube,
An initial resistance unit that controls a movement start load at which relative contraction movement at the time of impact starts between the outer peripheral portion of the inner tube and the outer tube, and a movement resistance unit that controls a movement load of relative contraction that is lower than the movement start load. The initial resistance portion is a press-fit portion with the inner tube press-fitted inside the outer tube, and the movement resistance portion has a movement resistance rib that interferes with the opening end of the outer tube in the axial direction of the outer peripheral portion of the inner tube. It has a predetermined length.

Here, the inner tube disposed on the inner side of the outer tube has a double-pipe structure in which a part of the inner tube overlaps, and energy is absorbed by contracting so that the inner tube is accommodated inside the outer tube.
In the present invention, the initial resistance portion refers to a resistance portion between the inner tube and the outer tube for expressing a load resistance necessary for the inner tube to start moving inside the outer tube.
When a contraction load exceeding the load resistance of the resistance portion is applied between the inner tube and the outer tube, contraction movement between the two begins.
In the present invention, the portion that becomes the resistance during the contraction movement is expressed as a movement resistance portion, and a load necessary for the contraction movement is expressed as a movement load.

When the steering shaft is rotatably supported inside the inner tube and the outer tube is assembled so as to partially overlap the outer side of the inner tube on the side of the wheel, during normal driving (before collision), traveling vibration is generated. The steering column may be loaded, and the outer tube and the inner tube must be securely fixed to each other.
Therefore, according to the present invention, an axial rib is formed on the outer peripheral portion of the inner tube, and the rib is used to press-fit the inner tube, and this press-fit portion acts as an initial resistance portion.
Moreover, when the inner tube was housed and contracted inside the outer tube, the rib of the inner tube was plastically deformed at the opening of the outer tube to form a movement resistance portion.
For plastic deformation of the rib, the rib may be sheared in the axial direction at the opening of the outer tube, or the rib may be deformed so as to be recessed inside the inner tube.
Accordingly, in the present invention, the rib includes all convex shapes formed in a strip shape along the axial direction.
In addition, when forming a rib that dents inwardly on the outer peripheral portion of the inner tube as the movement resistance portion, the outer peripheral portion of the inner tube has an axial rib extending from the initial resistance portion to the movement resistance portion, You may press-fit in the protrusion part provided in the inner side of the outer tube in the state which fitted the rigid member in the inner side located in the initial stage resistance part of an inner tube.
In this way, the inner tube is pressed from the inner side with a rigid member in the press-fitting portion of the inner tube, and the press-fitting strength with the outer tube is improved, and the press-fitting is performed by adjusting the strength and outer diameter of the rigid member. The strength, that is, the load to start moving the inner tube can be adjusted, and the inner tube begins to house and move inside the outer tube, and when the protruding portion of the outer tube is removed from the rigid member, the rib of the inner tube is deformed inward. The impact energy is absorbed by the storage movement of the inner tube.

Further, as a method of controlling the movement start load, a stepped portion protruding inside the outer tube may be formed, and an initial resistance rib that interferes with the protruding side portion of the stepped portion may be provided on the outer peripheral portion of the inner tube. Good.
If it does in this way, the initial resistance rib of an inner tube will interfere with the level | step-difference part of an outer tube, and a movement start load can be controlled by adjusting the width | variety and protrusion height of this initial resistance rib.
The inner tube has a two-step rib structure in which a first rib is formed along the axial direction of the outer peripheral portion and a second rib is formed on the upper surface of the first rib, and an initial resistance rib is formed by the first rib. The movement resistance portion can also be formed by the second rib.
In this case, the position of the step portion formed on the inner side of the outer tube is set to a position separated by a predetermined distance from the opening portion of the outer tube, and the first rib and the second rib formed on the inner tube are short in the axial direction. The moving load can be controlled by the shearing force applied to the second rib at the opening (opening end) of the outer tube, while leaving only the rib and controlling the movement starting load by plastic deformation of the first rib.
When such a structure is adopted, the movement start load can be set higher than the movement load by making the width of the first rib wider than the width of the second rib.

  An inner tube in which axial ribs are formed on the outer peripheral portion can be easily manufactured by using an extruded material or a drawn material of a light alloy such as an aluminum alloy or a magnesium alloy.

In the energy absorption column according to the present invention, by adopting a double tube structure in which the rib formed on the outer peripheral portion of the inner tube interferes with the opening of the outer tube or the protruding portion (stepped portion) formed on the inner side. The movement of the steering column when the steering column is contracted can be obtained by simply mounting a rigid member on the inner side of the inner tube located at the two-stage structure of the first rib and the second rib. A moving load lower than that can be set according to the target value.
In addition, by adopting such a structure, it is easy to manufacture the inner tube and outer tube with light alloy extruded material or drawn material, and the axial ribs increase the rigidity of the inner tube, and it is easy The structure is inexpensive and the energy absorption steering column is compact.

The example of the energy absorption steering column which concerns on this invention which consists of an outer tube and an inner tube is shown. The state before an outer tube and an inner tube are assembled is shown. (A) is an external view, (b) is a sectional view, (c) is an initial resistance rib (first rib), and (d) is a sectional view of a moving resistance rib (second rib). , (E) shows the dimensional relationship between the outer tube and the inner tube. The structural example of an outer tube is shown. An example in which an inner tube is press-fitted inside the outer tube is shown. The flow of energy absorption is shown schematically. An example of the rib shape of the inner tube and an example of the structure of the opening of the outer tube are shown. The other example of the rib shape of an inner tube is shown. An example in which a rigid member is fitted inside the inner tube is shown, (a) is an external view, (b) is a cross-sectional view, (c) is an enlarged view of a press-fitting portion, and (d) is an example of a rigid member. The dimensional relationship between the inner tube and the outer tube is shown, (a) is a sectional view of the press-fitting portion, (b) is a front view of the movement resistance portion, (c) is a dimensional relationship with the circumscribed circle of the rib, and (d) is a partially enlarged view. Indicates. The relationship between the contraction stroke of the steering column and the applied load is shown.

  Hereinafter, although the structural example of the energy absorption steering column which concerns on this invention is demonstrated based on drawing, it is not limited to these in the range of the meaning of invention.

As shown in FIG. 1, the steering column includes an inner tube 20 that rotatably supports the steering shaft 30 and an outer tube 10 that includes the inner tube 20 so as to partially overlap each other.
Although not shown, the steering shaft 30 is, for example, an upper shaft and a lower shaft that are connected so as to be capable of relative movement in the axial direction while transmitting rotational force by spline coupling or the like.
A steering wheel is attached to the upper part of the upper shaft, but the lower part of the lower shaft is connected to the steering mechanism.
Although the outer tube 10 is not shown, it is connected to a telescopic mechanism or the like.
The inner tube 20 and the outer tube 10 are fixed to each other so as to be able to withstand the vehicle running vibration and the occupant's operating load. When the occupant hits the steering wheel at the time of a secondary collision such as a vehicle collision, the impact is applied to the steering shaft. Is transmitted to the inner tube 20.
When the impact load is larger than a predetermined value, the impact energy is absorbed by the contraction so that the inner tube 20 is housed inside the outer tube 10, thereby protecting the occupant.
Here, the movement target load at which the inner tube 20 and the outer tube 10 start to contract and the subsequent movement load have different optimal target ranges depending on the vehicle specifications.
The movement start load is determined in consideration of the magnitude of the impact, and the subsequent movement load lower than that is determined in consideration of the product (energy absorption amount) with the movement stroke.

1 to 6 show a first embodiment.
The inner tube 20 is an example manufactured using an extruded material of an aluminum alloy.
As shown in FIG. 3 (d), the extruded shape member has a first rib on the base side (press-fit rib 21 and initial resistance rib 21 a) along the axial direction on the outer peripheral portion of the cylindrical inner tube, and a second on it. In the present embodiment, the two-step ribs of the ribs (movement resistance ribs 22) are formed in four strips.
The number of ribs is not limited as long as it is three or more.
Using such an extruded profile, only the necessary portion of the rib is left as it is, and the unnecessary portion is removed by cutting or the like to form an inner tube 20 as shown in FIG.
2 and 3, the second rib is removed from the rear of the inner tube 20 in FIG. 2, and the initial resistance rib 21a is formed leaving only the first rib. The first rib is also removed to form the length of the insertion portion 23.
Further, only the first rib is left in the front portion, the press-fitting rib 21 is left, and the second rib is left as it is, and the second rib is the movement resistance rib 22.

The outer tube 10 is also manufactured using an extruded material of an aluminum alloy, and an opening press-fitting portion 11 for inserting and press-fitting the inner tube 20 inward and a press-fitting step portion 12 for press-fitting the press-fitting portion 21b of the inner tube 20 are respectively provided on the inner side. The other part is cut and removed so that it protrudes toward.
An example of the outer tube 10 processed in this way is shown in FIG.
The procedure for press-fitting the inner tube 20 into the inner side of the outer tube 10 is shown in FIG. 5, and the dimensional relationship is shown in FIGS.
The outer diameter D3 of the first rib is set to be smaller than the inner diameter D2 of the opening of the outer tube so as not to interfere when the inner tube 20 is inserted into the outer tube 10, and more than the inner diameter D4 of the insertion portion of the outer tube 10. Also set a smaller value.
The outer diameter D5 of the press-fitting portion 21b formed by partially cutting the upper surface of the first rib is smaller than the outer diameter D3 of the first rib, but is slightly larger than the inner diameter D1 of the press-fitting step portion 12 of the outer tube 10.
The inner diameter D2 of the opening press-fit portion of the outer tube is set slightly smaller than the outer diameter D3 of the first rib from which the second rib is removed.
When the dimensional relationship is set in this way and assembled as shown in FIG. 5, the inner tube press-fitting portion 21b is press-fitted into the outer tube press-fitting step portion 12, and the inner tube press-fitting rib 21 is the outer tube open press-fitting portion 11. Thus, the inner tube 20 and the outer tube 10 are press-fitted and fixed at the two locations.
When press-fitting and fixing in this manner, the initial resistance rib 21a of the inner tube interferes in a state where it is in contact with the step side surface of the press-fitting step portion 12 of the outer tube.
In addition, the tip of the outer tube opening press-fit portion 11 is located near the cut-out side surface of the movement resistance rib 22.

When an impact load is applied to the inner tube 20, the initial resistance rib 21a interferes with the step side surface of the press-fitting step portion 12 of the outer tube 10 as shown in FIG. The press-fitting strength and the load for plastic deformation of the initial resistance rib 21a become the movement start load.
When the initial resistance rib 21a is plastically deformed and crushed, the inner tube 20 is housed and moved inside the outer tube 10. At this time, the opening tip 11a of the outer tube 10 is housed while interfering with the movement resistance rib 22. Moving.
The product of the moving load applied at this time and the moving stroke length is the amount of energy absorption.
In the embodiment shown in FIG. 6, the movement resistance rib 22 is an example of absorbing energy while becoming a shear piece 22a.
Therefore, the movement start load can be adjusted by adjusting the width d1 and the height of the initial resistance rib, and the movement load can be adjusted by adjusting the width d2 and the height H of the movement resistance rib 22. .
In addition, the axial length of the initial resistance rib 21a must be short so that it immediately leads to the subsequent moving load, but the axial length of the moving resistance rib 22 is set to be long in accordance with the required energy absorption amount. To do.
Further, as shown in FIG. 7, the shearing force can be adjusted by inserting a notch 22b in the side surface of the movement resistance rib 22 or adjusting the taper angle θ of the opening end of the outer tube.
Furthermore, as shown in FIG. 8, a thin portion 24 may be formed inside the inner tube 20 corresponding to the position of the movement resistance rib 23 so that the rib is deformed inward.

9 and 10 show a second embodiment.
In the cross-sectional shape of the inner tube 20, the circumscribed circle diameter DA of the axial convex portion 25 is set larger than the outer diameter DC of the general portion, and the circumscribed circle diameter DA of the convex portion 25 is larger than the inner diameter DB of the outer tube 10. Set.
A highly rigid ring-shaped rigid member 30 is fitted inside the press-fitting portion of the inner tube 20.
When the inner tube 20 is press-fitted into the outer tube 10 in such a state, the convex portion 25 is press-fitted so as to be dented inward, but since the rigid member 30 is provided on the inner side, a biasing force acts on the outer side, and the press-fitting strength is increased. Get higher.
Accordingly, when the press-fitting strength becomes a movement start load at the time of impact, the movement of the inner tube 20 starts, and the opening press-fitting portion 11 protruding inside the outer tube 10 deviates from the position of the rigid member 30, the convex portion 25. Is deformed inward from the thin-walled portions 26 on both sides, and the force becomes a moving load.
When such an example of the inner tube structure is adopted, it is not necessary to remove the rib part, and the inner tube can be manufactured at a lower cost.

DESCRIPTION OF SYMBOLS 10 Outer tube 11 Opening press-fit part 12 Press-fit level | step difference part 20 Inner tube 21 Press-fit rib 21a Initial resistance rib 21b Press-fit part 22 Movement resistance rib 23 Insertion part 30 Steering shaft

Claims (5)

An outer tube and an inner tube disposed so as to contract and move due to impact inside the outer tube,
An initial resistance unit that controls a movement start load at which relative contraction movement at the time of impact starts between the outer peripheral portion of the inner tube and the outer tube, and a movement resistance unit that controls a movement load of relative contraction that is lower than the movement start load. Have
The initial resistance portion is a press-fitting portion with an inner tube press-fitted inside the outer tube,
The energy absorption steering column according to claim 1, wherein the movement resistance portion has a movement resistance rib having a predetermined length in the axial direction of the outer peripheral portion of the inner tube.   2. The energy absorbing steering column according to claim 1, wherein the initial resistance portion further includes an initial resistance rib on an outer peripheral portion of the inner tube that interferes with a step portion formed to protrude inside the outer tube. Having an axial rib on the outer peripheral portion of the inner tube from the initial resistance portion to the movement resistance portion;
The inner tube located at the initial resistance portion of the inner tube is press-fitted into a protruding portion provided on the inner side of the outer tube with a rigid member fitted, and the movement resistance portion is accompanied by relative contraction of the outer tube and the inner tube. 2. The energy absorbing steering column according to claim 1, wherein energy is absorbed by a rib provided on an outer peripheral portion of the inner tube being deformed inward.   The inner tube has a two-step rib structure in which the first rib is formed along the axial direction of the outer peripheral portion and the second rib is formed on the upper surface of the first rib, and the first resistance rib is formed by the first rib. 3. The energy absorption steering column according to claim 2, wherein the movement resistance portion is formed by two ribs.   The energy absorbing steering column according to any one of claims 1 to 4, wherein the inner tube is manufactured using a light alloy extruded material having ribs along an axial direction of an outer peripheral portion.

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