JPS63255171A - Energy absorbing type steering device - Google Patents

Abstract

PURPOSE:To improve an energy absorbing effect with a low cost structure by forming a fit-in part with two circular arc face parts, in a device in which two coaxial steering columns are axially slidably fitted to each other at their opposite end parts. CONSTITUTION:A steering wheel 1 is fixed to the top end of an upper shaft 2, which is slidably installed to a lower shaft 5 by fitting a two-flat face tube 3 which is fixed to its lower end to a two-flat face part 4 provided on the upper end of the lower shaft 5. In this case, the lower end part of an outer column 8 the upper end of which is removably supported by an installment panel 10 via an upper bracket 9 is fitted on an inner column 11. And, two mutually opposing circular arc face parts which are brought into contact with the inner column 11 are formed ranging over approx. 60 deg. on the fit-in part of the outer column 8, and a defined pressing force is given to the inner column 11 through the circular arc face parts.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides an energy-absorbing steering system that reduces injury to the driver due to a secondary collision with the steering wheel due to the contraction of the axial strength in the event of a collision with an automobile, etc. It is related to the device.

[Prior Art] A technical concept in which a steering column is divided and the column contracts in the axial direction to absorb collision energy is disclosed, for example, in Japanese Utility Model Application Publication No. 53-98430. As a means of holding the steering column to the vehicle body so that it can move downward in the axial direction, shafts are installed at several points in the circumferential direction of either one of the fitting surfaces between the bracket dash, etc. and the steering column. A method in which a protrusion extending in the direction is provided, and the number and size of the protrusion are determined appropriately to set the sliding resistance in the axial direction of the steering column to a slight or arbitrary value; −
As shown in Publication No. 6074, the outer peripheral surface of either the first column divided body or the fjS2 column divided body of the steering column is made circular, and the Ikekata divided body is in surface contact with the circular outer peripheral surface. An energy-absorbing steering device is known in which a connecting cylindrical portion is formed with a plurality of planar contact walls, and one of the divided bodies is press-fitted into the connecting cylindrical portion to connect both columns.

[Problem to be Solved by the Invention 1] In the technique disclosed in the above-mentioned Japanese Utility Model Application Publication No. 53-98430, the fitting is performed by a narrow protruding portion. The joint portion becomes a line contact, and due to variations in the diameter of the column, the interference may be excessively large, resulting in increased contact pressure and plastic deformation at the contact portion during fitting.

As a result, in a secondary collision, when the driver collides with the steering wheel and a horizontal impact force is applied, the steering column fitting part tends to rotate around the bracket part that supports the upper column to the vehicle body part. A bending moment load occurs. In this case, the contact pressure of the protruding part of the column fitting part increases, and phenomena such as galling and digging occur in the fitting part, making it difficult to slide in the axial direction and increasing the sliding load. This prevents energy absorption and poses a danger to the human body. In addition, in order to maintain the rigidity of the steering column and allow the steering column to move downward smoothly in the event of a collision, the fitting must be made so that the sliding load is within a certain range, but in reality, the fitting Fluctuations in the dimensional accuracy between the inner diameter of the outer member and the outer diameter of the inner member greatly affect the sliding load, and a pipe material with good dimensional accuracy in the inner diameter or outer diameter has the disadvantage of being expensive. - It was difficult to use electric resistance welded pipes that had not been subjected to the drawing process due to the cost of paper and the variation in diameter dimensions. Furthermore, it was necessary to reduce the variation in the protrusions from one method to another, which required a large number of processing steps.

In addition, in the technology disclosed in Japanese Utility Model Application 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 avoid excessive surface pressure at the contact part. The occurrence of this is unavoidable, and as with the above technology, it includes the problems α of difficulty in sliding when a bending moment load is applied and the need for good dimensional accuracy of the fitting portion. In addition, in order to hold the column contact part without warping, it is necessary to make contact with large contact pressure at four points on the circumference as shown in Fig. 5, and the non-contact part and the outer circumferential surface of the inner column The gap between the two columns 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 and outer diameters of the contact part within a small range, and either use pipe material with good dimensional accuracy, or
Selective fitting must be performed, which increases costs, or inventory accumulates due to selective fitting, resulting in extremely low efficiency.

On the other hand, due to the contact between the cylinder and the flat surface, the contact area is small, so the contact part is likely to wear out due to the vibration of the ■μ vehicle, and looseness is likely to occur.As a countermeasure, the number of flat surfaces as polygons is increased in order to increase the contact area. There must be. As a result, the elastic action of the outer column is limited and tubing with increasingly high dimensional accuracy is required.

Furthermore, a protrusion such as a tongue is provided on the outer column,
Types that make contact with the inner column are known, but conventional types require a press die to process the tongue, which increases the number of processing steps, increases surface pressure at the contact area, and reduces dimensional accuracy. It also includes the issue of necessity.

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

Means for Solving Problem E] In order to solve the above problem, two steering columns that rotatably support a 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 which is held in a vehicle body part 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. and having a radius smaller than the diameter of the outer surface of the inner steering column,
The two arcuate surface portions are connected by a connecting portion that forms a space between the inner column and the inner column, and the inner column applies a predetermined pressure by the front arched surface portion of the outer column. In this way, an energy-absorbing steering device was constructed.

[Function 1] 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 are in contact with the inner column. Because of this structure, the spring constant in the direction of widening the opposing arcuate surfaces can be made small, and even if there is a large variation in the outer diameter of the inner column, the surface pressure on 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, The stress at the end of the abutment part is not high, and the sliding movement of both columns is not inhibited.1 Furthermore, at the fitting part, the outer column has two opposing circular arc parts that contact the inner column. Therefore, the fitting portions of both columns are supported with rigidity even in a plane including the axis and perpendicular to a plane that includes the axis and passes through the center of the circular arc surface that is the contact portion.

[Example 1 Embodiments of the present invention will be described in detail below based on the drawings.

Figure f51 and Figure f:tS2 show the energy absorbing steering device of the present invention. The steering wheel 1 is fixed to the upper end of the upper shaft 2.
A biplane tube 3 is fixed to the lower end of the lower shaft 5, and a lower shaft 5 having a biplane portion 4 at its upper end is fitted into the biplane tube 3.

The lower end of the lower shaft 5 is connected to an intermediate shaft 7 via a universal joint 6, and is 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 attached to the instrument panel 10 by a known structure that can be removed only toward the lower steering gear side. Lower bracket 12 is located below the vehicle body.
is fixed, and the lower end portion of the inner column 11, which is fitted into the outer column 8, is supported by a lower bracket 12. At the fitting portion, the end portion 13 of the outer column 8 extends outward over the entire circumference of the tormendo panel 1.
The outer column 8 and the inner column 11 slide at the fitting portion of the two columns while absorbing some of the energy of the collision. At this time, as shown in FIG. An annular concave non-contact part is provided at the center of the arcuate contact part in the column axis direction to improve the bending rigidity of both column fitting parts and stabilize the sliding load.

Figure fjS3 shows a cross-sectional view of the column fitting part. The outer column 8 has two opposing arcuate surface portions that abut the inner column 11 and are formed over a range of a central angle of 60'', and the arcuate surface portions have a radius of about 85% of the radius of the outer surface of the inner column 11. They are connected by an arc-shaped part that is a connecting part.Also, by changing the circumferential direction of the arc-shaped abutment part, the arc-shaped abutment part and both column pongee cores can be connected without changing the sliding load of the mating part. It is possible to easily design a column that meets the requirements for the bending rigidity ratio of the column in a plane including the plane and in a plane perpendicular to the plane.

In the above embodiment, the central angle of the two opposing arcuate surfaces where both columns abut is approximately 60°, but this angle may be changed as long as the lateral rigidity of the fitting portion of both columns can be ensured. It is not something that can be taken away.

In the above embodiment, the connecting portion that connects the two circular arc surface portions of the outer column is also a circular arc portion having a radius of about 85% of the radius of the outer surface of the inner column.
It is not limited to about 85% as long as the bending rigidity of the fitting portion of both columns can be ensured and energy absorption is not inhibited.

Further, in the embodiment described above, the impact energy due to a secondary collision is absorbed by the attachment part of the upper bracket 9 to the instrument panel 10, but the impact energy may be absorbed by the steering shaft part. good.

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

[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 scratches and digging do not occur, an energy-absorbing steering device with stable energy-absorbing performance can be obtained.Furthermore, even if the diameter of the column material varies, the arc of the outer column that abuts the inner column remains constant. The variation in the inner diameter of the surface part can be reduced, the sliding load can be kept within the specified fa range, an inexpensive electric resistance welded tube that is still welded and does not need to be drawn can be used as the steering column, and the outer column can be used as the inner column. Machining of the two abutting circular arc surfaces is now possible using an inexpensive press using a core metal and a die, and an energy-absorbing steering device that contracts smoothly even when a bending moment is applied to the mating part has become possible. U gets hit.

Furthermore, the vehicle J1 required for the steering device
Sufficient downward rigidity is ensured as well as horizontal rigidity, and the balance between vertical and horizontal rigidity of the vehicle can be easily met by a design that changes the arcuate contact quality in the circumferential direction. be able to.

[Brief explanation of the drawing]

Fig. fjS1 is a side view showing one 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. 11, and Fig. 3 is a line AA# of Fig. 2; The cross-sectional view at t, Figure 4 and Figure fjs5 are A-A of the conventional example.
It is a figure corresponding to a cross section. Explanation of symbols 1 Steering wheel 2 Upper shaft 5 Lower shaft 8 Outer column 9 Upper bracket 11 Inner column 12 Lower bracket 1, Applicant NSK Ltd. 1 Figure 11 Inner column 12 Lower bracket 0. to

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 when one column receives an impact during a collision, the other column is movable axially downward as a part of the vehicle body. In the energy absorbing steering device, the outer steering column has two opposing arcuate surface portions that abut the inner steering column at the fitting portion, and The two arcuate surface portions are connected by a connecting portion having a radius smaller than the radius of the outer surface of the steering column and forming a space between the inner column and the outer column, the inner column being connected to the outer surface of the steering column. An energy absorbing steering device, characterized in that a predetermined pressure is applied by the arcuate surface portion of the column.