JPH0457541B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is an energy absorbing type that reduces injury to the driver due to a secondary collision with the steering wheel in the event of a collision with an automobile, etc. by contracting the length in the axial direction. This relates to a steering device.

[Prior Art] A technical concept in which the steering column is divided and the column contracts in the axial direction to absorb collision energy is, for example, disclosed in U.S. Pat.
As disclosed in Publication No. 98430, as a means for holding the steering column on the vehicle body so that it can move downward in the axial direction, a circle on one of the fitting surfaces of the steering column and the bracket darts, etc. Protrusions extending in the axial direction are provided at several locations in the circumferential direction, and the number and dimensions of the protrusions are appropriately determined to set the axial sliding resistance of the steering column to a small arbitrary value. Furthermore, as shown in Japanese Utility Model Application Publication No. 62-6074, the outer peripheral surface of either the first column division body or the second column division body of the steering column is made circular, and the other division body is made circular. , an energy absorbing steering device in which a connecting tube section is formed with a plurality of planar contact walls that are in surface contact with the circular outer circumferential surface, and the one divided body is press-fitted into the connecting tube section to connect both columns. It has been known.

[Problems to be Solved by the Invention] The technology disclosed in the above-mentioned Japanese Utility Model Publication No. 53-98430 maintains the rigidity of the steering column, and also prevents the steering column from sliding in order to smoothly move downward in the event of a collision. It is necessary to fit the load within a certain range, but variations in the dimensional accuracy of the inner diameter of the outer member and the outer diameter of the inner member of the mating part affect the sliding load, so the cost is high and the inner diameter Another drawback is that it requires a tube material with high dimensional accuracy in outer diameter. Naturally, it was also difficult to employ low-cost electric resistance welded pipes that had not been drawn because of the variation in diameter. Furthermore, it was necessary to reduce the variation in the dimensions of the protruding portions, which required a large number of processing steps.

In addition, in the technology disclosed in Japanese Utility Model Publication No. 62-6074, since the contact part is cylindrical and flat, the contact area is small, and in order to satisfy the energy absorption performance, it is necessary to As a result, when the driver collides with the steering wheel during a secondary collision and a horizontal impact force is applied, the upper column tends to rotate around the bracket that supports the vehicle body. In this case, a bending moment load is generated at the steering column fitting part, but in this case, the surface pressure of the contact part of the column fitting part becomes large, and phenomena such as galling or digging occur in the fitting part, and the axial direction This includes the problem that good dimensional accuracy of the fitting portion is required since sliding becomes difficult. In addition, in order to hold the column contact part without play, it is necessary to make contact with large contact pressure at four points on the circumference as shown in Figure 5, and the non-contact part and the outer peripheral surface of the inner column The gap becomes smaller, the elastic action of the outer column is restricted, and the change in the load acting on the contact part due to the radial displacement of the contact part becomes large, so in order to keep the sliding load within a constant value, It is necessary to keep the difference between the inner diameter and outer diameter of the contact part within a small range, and it is necessary to use pipe material with good dimensional accuracy or to selectively fit, which increases costs, or because of selective fitting, inventory is limited. This resulted in a stagnation, resulting in extremely poor efficiency.

On the other hand, due to the contact between the cylinder and the plane, the contact area is small, so the contact part will wear out due to vehicle vibration.
Backlash is likely to occur, and as a countermeasure, it is necessary to increase the number of polygonal planes in order to increase the contact area. This limits the elastic action of the outer column,
Piping materials with increasingly high dimensional accuracy are required.

Furthermore, there is also a known type in which the outer column is provided with a protrusion such as a tongue, which makes contact with the inner column, but in the conventional type, a press die is used to process the tongue. In addition to requiring additional processing man-hours, there are also problems in that the surface pressure of the contact portion increases and dimensional accuracy is required.

The present invention was made to solve the problems of the conventional technology, and an object of the present invention is to provide an energy-absorbing steering device that is inexpensive and has good sliding performance.

[Means for Solving the Problems] In order to solve the above problems, two steering columns that rotatably support the steering shaft are fitted into each other at the ends of the columns, and one column is prevented from colliding. In an energy-absorbing steering device that is held in a vehicle body portion so as to be able to move downward in the axial direction when subjected to an impact, in the present invention, the outer steering column at the fitting portion is connected to the inner steering column. said two opposing circular arc surface portions abutting said inner steering column and having a radius smaller than the radius of the outer surface of said inner steering column and forming a space between said two. The two arcuate surface portions are connected, and the inner column applies a predetermined pressure by the arcuate portion of the outer column, thereby constructing an energy absorbing steering device.

[Operation] According to the configuration of the present invention, the outer column has two opposing arcuate surface portions that abut the inner column, and the two arcuate surface portions have a radius of the outer surface of the inner column. Since the structure is such that the connection is made by a connecting part that has a radius smaller than that of the inner column and forms a space between it and the inner column, the spring constant in the direction of expanding the opposing circular arc surfaces can be reduced, and the inner column Even if there is a large variation in outer diameter dimensions, the surface pressure of the fitting portion will not become excessive.

Therefore, since the abutting portions of both columns are elastically acted by the outer column and the abutting portions have a predetermined width in the axial direction, even if a bending moment load is applied to the fitting portion, Stress at the ends of the abutting portions is not increased, and sliding of both columns is not inhibited.

Furthermore, in the fitting part, the outer column has two opposing arcuate parts that contact the inner column, so it is perpendicular to a plane that includes the axis and passes through the center of the arcuate surface that is the contact part. The fitting portions of both columns are supported with rigidity also in a plane including the axis of the column.

[Example] Hereinafter, an example of the present invention will be described in detail based on the drawings.

1 and 2 show an energy absorbing steering device of the present invention. The steering wheel 1 is fixed to the upper end of an upper shaft 2, a biplane tube 3 is fixed to the lower end of the upper shaft 2, and a lower shaft 5 is provided with a biplane portion 4 at the upper end.
is fitted into the biplanar tube 3.

The lower end of the lower shaft 5 is connected to an intermediate shaft 7 via a universal joint 6, and further connected to a steering gear (not shown) so as to transmit torque. The outer column 8 that rotatably supports the upper shaft 2 is supported at its upper end by an upper bracket 9 that is attached to the instrument panel 10 by a known structure that can be removed only toward the lower steering gear side. There is. A lower bracket 12 is fixed to the lower part of the vehicle body, and the lower end portion of the inner column 11 fitted into the outer column 8 is supported by the lower bracket 12. At the fitting portion, the end portion 13 of the outer column 8 is bent so as to spread outward over the entire circumference.

In the event of a collision with a motor vehicle, etc., the driver must turn the steering wheel 1.
When a secondary collision occurs, the upper bracket 9 separates downward from the mounting part of the instrument panel 10, and the outer column 8 and inner column 11 slide at the fitting part of both columns while absorbing some of the energy of the collision. . At this time, as shown in FIG. 2, the upper shaft 2 and lower shaft 5 also slide due to the two-plane portion 4 of the two-plane tube 3 and lower shaft 5. The fitting part between the outer column 8 and the inner column 11 is provided with an annular concave non-contact part at the center of the arcuate contact part in the column axis direction, thereby improving the bending rigidity of the fitting part of both columns and reducing the sliding load. I'm trying to find stability.

FIG. 3 shows a cross-sectional view of the column fitting part. The outer column 8 has two opposing arcuate surface portions that come into contact with the inner column 11 and are formed over a central angle of 60°, and the arcuate surface portions have a radius of approximately 85% of the radius of the outer surface of the inner column 11. They are connected by an arc-shaped connecting part. In addition, by changing the circumferential length of the arc-shaped abutment part, the sliding load of the fitting part can be maintained without changing in the plane including the arc-shaped abutment part and both column axes, and in the plane orthogonal to the plane. It is possible to easily design a column that meets the requirements for the bending stiffness ratio of the column.

In addition, in the above embodiment, the two columns are in contact with each other.
Although the central angle of the two opposing circular arc surface portions was set to approximately 60°, this angle is not limited as long as the lateral rigidity of the fitting portion of both columns can be ensured. In the above embodiment, the connecting portion connecting the two circular arc surface portions of the outer column is also a circular arc portion having a radius of approximately 85% of the radius of the outer surface of the inner column. It is not limited to about 85% as long as bending rigidity can be ensured and energy absorption is not inhibited.

Further, in the above embodiment, the upper bracket 9
Although the impact energy due to the secondary collision is absorbed at the attachment part to the instrument panel 10, the impact energy may be absorbed at the steering shaft part.

Further, in the above embodiment, the tilt angle of the steering shaft is constant, but it goes without saying that the present invention can be applied to a tilt type steering device in which the tilt angle of the steering shaft can be changed.

[Effects of the Invention] Since the above-mentioned action is performed, even if the driver collides with the steering wheel in a secondary collision and a horizontal load is applied, and a bending moment is applied to the steering column fitting part, the fitting part remains intact. Since phenomena such as galling and digging do not occur, an energy-absorbing steering device with stable energy absorption performance can be obtained.Furthermore, even if the diameter of the column material varies, the arcuate surface of the outer column that contacts the inner column Variations in the internal diameter of the parts can be reduced, the sliding load can be kept within a specified range, and an inexpensive ERW tube that is welded and not drawn can be used as the steering column, and the outer column abuts the inner column. Machining of the two arcuate surface parts is also possible using an inexpensive press method using a core metal and a pressing die, and an energy-absorbing steering device that contracts smoothly even when a bending moment is applied to the fitting part can be obtained.

Furthermore, what is required of a steering device is
Sufficient rigidity in the vertical direction of the vehicle is ensured, as is rigidity in the horizontal direction, and the balance of rigidity in the vertical and horizontal directions of the vehicle can be easily met by a design that changes the arcuate contact length in the circumferential direction. be able to.

[Brief explanation of the drawing]

FIG. 1 is a side view showing an embodiment of the energy absorbing steering device according to the present invention, FIG. 2 is a vertical sectional view of the main part of FIG. 1, and FIG.
The cross-sectional views taken along line A, FIGS. 4 and 5, are views corresponding to the A-A cross section of the conventional example. Explanation of symbols, 1...Steering wheel, 2
...Atsupahshaft, 5...Lower shaft,
8...Outer column, 9...Upper bracket, 11...Inner column, 12...Lower bracket.

Claims (1)

[Claims] 1 Two steering columns that rotatably support a steering shaft are fitted into each other at the ends of the columns, and one of the columns is held in the vehicle body so that it can move axially downward when it receives an impact during a collision. In the energy absorbing steering device, in the fitting portion, the outer steering column has two opposing circular arc surface portions that abut the inner steering column, and the inner steering column The two arcuate surface portions are connected by a connecting portion having a radius smaller than the radius of the outer surface of the column and forming a space between the inner column and the outer column, and the inner column is connected to the outer column. An energy absorbing steering device, wherein a predetermined pressure is applied by the arcuate surface portion of the energy absorbing steering device.