Title of Invention

"SHOCK ABSORBING DEVICE FOR STEERING COLUMNS"

Abstract

A shock absorbing device for steering columns is disclosed. The shock absorbing device is provided in the interferential fitting junction between the upper and lower columns of a steering column. The shock absorbing device has a plurality of friction members, which are formed on the upper column by a piercing process with the base part of each friction member being exposed outside the upper column and the other part being folded down into the internal surface of the upper column to form a friction part. The friction part is brought into frictional contact with the external surface of the lower column, thus enlarging the frictional contact area of the shock absorbing device. The shock absorbing device effectively absorbs and relieves shock in the initial stage of a car collision, thus effectively preventing the shock from being transmitted to a steering wheel in order to protect the driver in a collision.

Full Text

..... BACKGROUND OF THE INVENTION 1. Field of the Invention The present; invention relates to a shock absorbing device for steering columns, and more particularly to a shock absorbing device for effectively absorbing and relieving shock applied to a steering column in the initial stage of a car collision, thus effectively preventing the shock from being transmitted to a steering wheel and protecting a driver in the event of a collision. 2. Description of the Prior Art Figs. 1 and 2 show the construction of a typical shock absorbing device for steering columns. As shown in the drawings, the steering column comprises a cylindrical upper column 10 and a cylindrical lower column 20, with one end of the lower column 20 being interferentially fitted into the upper column 10 thus forming a shock absorbing device in the interferential fitting junction between the two columns 10 and 20. The shock absorbing device includes a plurality of regularly-spaced linear lugs 21, which are axially formed on the fitting part of the lower column 20. Due to the linear lugs 21, the lower column 20 is able to be interferentially fitted into the upper column 10. The linear lugs 21 are preferably formed on the lower column 20 by a pressing process. The upper and lower columns 10 and 20 are respectively mounted to the upper and lower portions of a car body using mounting brackets (not shown). In case of a collision, the lower column 20 frictionally retracts into the upper column 10 so that the junction between the internal surface of the upper column 10 and the linear lugs 21 of the lower column 20 absorb and relieve the collision impact applied to a steering wheel through the steering column. The shock absorbing device for steering column thus protects a driver from such a collision impact. Fig. 3 is a chart showing the impact absorbing characteristic of a typical shock absorbing device of a steering column during the car collision. As shown in Fig. 3, the collision impact load (kgf) , which is absorbed by the junction between the internal surface of the upper column 10 and the linear lugs 21 of the lower column 20 , is rapidly increased reaching a peak point within a very short time during the collision. After reaching the peak point, the absorbed impact load is constantly maintained at about 200 kgf due to the relative displacement between the upper and lower columns 10 and 20. Such a peak point of the absorbed impact load is caused by the fact that the upper column 10 is hardly deformed in the initial stage of the retraction of the lower column 20 into the upper column 10 thus preventing the lower column 20 from easily retracting into the upper column 10. This is represented by the relative displacement (stroke) between the two columns 10 and 20 being extremely small at the peak point of the load. Such a small displacement between the two columns 10 and 20 in the initial stage of the collision means that the collision impact is directly applied to the steering wheel through the steering column. Therefore, a typical shock absorbing device for steering columns fails to rapidly and effectively absorb the collision impact in the initial stage of a car collision, but rather transmits the impact to the steering wheel through the two columns 10 and 20 and in turn to the driver . Such shock absorbing device is ineffective in protecting the driver in the event of a collision. As described above, the impact load caused by a car collision constantly maintained after the peak point. However, since the collision impact is instantaneously generated during the collision, the interferential fitting junction between upper and lower columns 10 and 20 requires a rapidly deforming characteristic to effectively absorb the impact in the initial stage of a collision. Another problem experienced by a typical shock absorbing device is that it is very difficult to obtain a predetermined size of the linear lugs 21 from the pressing process. Therefore, it is difficult to effectively controll the impact load. The steering column with such shock absorbing device is also problematic in that the upper and lower columns 10 and 20 are welded to a car body, causing a welding strain in each column 10, 20. Due to such welding strain, the junction between the internal surface of the upper column 10 and the external surface of the lower column 20 may be deformed, failing to maintain the designed structure of junction. Therefore, the impact load, which can be effectively absorbed by the shock absorbing device in the case of a collision, cannot be accurately determined. SUMMARY OF THE INVENTION In view of the foregoing, it is an object of the present invention is to provide a shock absorbing device for steering columns, which effectively absorbs and re-lieves shock applied to a steering column in the initial stage of a car collision, thus preventing the shock from 5 being transmitted to a steering wheel and to the driver in the event of acollision. Another object of the present invention is to provide a shock absorbing device for steering columns, which collapses along with a steering column during the car collision thus reliably absorbing and relieving shock caused by the collision. In order to accomplish the above objects, the present invention provides A shock absorbing device provided in an interferential fitting junction between upper and lower columns of a steering column, with the lower column being interferentially fitted into the upper column, and adapted for absorbing and relieving shock applied to the steering column in the initial stage of a collision, comprising: a plurality of friction members formed on the upper column by a piercing process at a positions around the interferential fitting junction, each of said plurality of friction members being folded down into the upper column to be brought into the frictional contact with an external surface of the lower column when the lower column is fitted into the upper column, Wherein each of said plurality of friction members comprises: a base part exposed facing the outside of the upper column; and, a friction part integrally extending from said base part and folded down into the upper column to be brought into close contact with an internal surface of the upper column, said friction part coming into frictional contact with the external surface of the lower column when the lower column is fitted into the upper column. said upper column is inwardly rounded on opposite corners to form a neck having opposingly concave webs to form a narrowed junction between said base part of each of said plurality of friction members and a main body. Each of the friction members comprises a base part exposed outside the upper column and a friction part integrally extending from the base part and folded down into the upper column to be brought into close contact with the internal surface of the upper column. The friction part comes into frictional contact with the external surface of the lower column when the lower column is fitted into the upper column. The junction between the base part of each friction member and the main body the upper column is inwardly rounded on opposite corners, thus forming a neck with opposite rounded webs. In another embodiment, the shock absorbing device also includes a plurality of inward projections, which are formed on the internal surface of the upper column and are brought into frictional contact with the external surface of the lower column. BRIEF DESCRIPTION OF THE DRAWINGS The above and other objects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which: Fig. 1 is a longitudinal-sectional view showing the construction of a conventional shock absorbing device for steering columns; Fig. 2 is cross-sectional view of the shock absorbing device taken along the line A-A' of Fig. 1; Fig. 3 is a chart showing the impact absorbing characteristic of a typical shock absorbing device during the car collision; Fig. 4 is a side view of a steering column with a shock absorbing device according to a preffered embodiment of the present invention; Fig. 5 is a perspective view of the shock absorbing device of the present invention; Fig. 6 is a longitudinal-sectional view of the shock absorbing device of the present invention; Fig. 7 is a cross-sectional view of the shock absorbing device of the present invention; Fig. 8 is a chart showing the impact absorbing characteristic of the shock absorbing device of the present invention during the collision; and Fig. 9 is a longitudinal-sectional view of a shock absorbing device for steering columns according to another embodiment of the present invention. DESCRIPTION OF THE PREFERRED EMBODIMENTS Fig. 4 is a side view of a steering column with a shock absorbing device according to a preferred embodiment of the present invention. As shown in the drawing, the two mounting brackets 101 and 102 are welded to upper and lower portions of a car body 100, while upper and lower columns 110 and 120 are welded to the brackets 101 and 102 respectively, with one end of the lower column 120 being interferentially fitted into the upper column 110 thus forming a shock absorbing device in the interferential fitting junction between the two columns 110 and 120. A steering wheel 130 is connected to the top end of the upper columns 110. As shown in Figs. 5 to 7, the upper column 110 is a cylindrical body, which is provided with a plurality of friction members 111 on the fitting part. The number of the friction members 111 varies in accordance with a car. The friction members 111 are preferably formed on the upper column 110 by a piercing process, with the base part 113 of each friction member 111 being exposed outside the column 110 and the other part being folded down into the column 110 to form a friction part 112, which is brought into close contact with the internal surface of the upper column 110. That is, the friction part 112, which integrally extends from the base part 113, is folded down thus being overlapped under the base part 113. The junction between the base part 113 and the main body the column 110 is inwardly rounded on opposite corners, thus forming a neck with opposite rounded webs 114 and 114'. The rounded webs 114 and 114' of the neck not only allow each friction member 111 to be easily folded down, they also prevent a crack or stress concentration on the corners. In addition, the rounded webs 114 and 114' allow each folded friction member 111 to be easily deformed toward the outside of the column 110 when the lower column 120 forcibly retracts into the upper column 110 in the initial stage of a car collision. In the above shock absorbing device, the friction members 111 of the upper column 110 are all brought into frictional contact with the external surface of the lower column 120 by having the lower column 120 interferentially fitted into the upper column 110. The above friction members 111 thus effectively absorb and relieve the collision impact by the frictional force generated between the members 111 and the external surface of the lower column 120 when the lower column 120 retracts into the upper column 110 in the initial stage of a car collision. In a preferred embodiment of the present invention, the friction members 111 are circumferentially arranged on the upper column 110 at regular intervals. However, it should be understood that the friction members 111 may be irregularly arranged on the upper column 110. The operational effect of the above shock absorbing device will be described hereinbelow. During the collision, the lower column 120 forcibly retracts into the upper column 110 at the interferential fitting junction between the two columns 110 and 120 while effectively absorbing and intercepting the impact load before the load is applied to the steering wheel 130. When the lower column 120 retracts into the upper column 110 in the initial stage of the car collision, the friction members 111 of the upper column 110 absorb the impact load by the frictional force generated between the friction members 111 and the external surface of the lower column 120. That is, the friction members 111 of the upper column 110 and the external surface of the lower column 120 frictionally move relative to each other in the initial stage of the car collision so that the members 111 smoothly absorb the impact load and effectively intercept the load before the load is applied to the steering wheel 130 through the upper column 110. When the lower column 120 retracts further into the upper column 110 during collision, the frictional contact area between each friction member 111 and the external surface of the lower column 110 is remarkably increased, thus more effectively absorbing the impact load. When the lower column 120 forcibly retracts into the upper column 110 in the initial stage of a car collision, each folded friction member 111 deforms at the base part 113 toward the outside of the upper column 110 to absorb part of the impact load. In the above state, the rounded webs 114 and 114' formed on the neck of each friction member 111 allow the member 111 to be easily deformed. Fig. 8 is a chart showing the impact absorbing characteristic of the shock absorbing device of the present invention during the collision. As shown in Fig. 8, the shock absorbing device of the present invention absorbs and relieves the impact load applied to the steering column in the initial stage of the car collision without exceeding the impact load over 200 kgf. Therefore, this differents from the conventional device the peak is not reached. The removal of the peak is caused by the friction members 111, deforming toward the outside of the upper column 110 in the initial stage of the collision. In the shock absorbing device of the present invention, a gap, which is equal to the thickness of each friction member 111, exists in the interferential fitting junction between the upper and lower columns 110 and 120. Due to the existence of such a gap in the junction between the two columns 110 and 120, the impact absorbing capacity of the shock absorbing device is not altered irrespective of welding strain caused by a welding process for welding the columns 110 and 120 to the mounting brackets 101 and 102. Therefore, the shock absorbing device of this invention effectively maintains the predetermined impact absorbing capacity regardless of such a welding process. Fig. 9 is a longitudinal-sectional view of a shock absorbing device for steering columns according to the second preferred embodiment of the present invention. In the shock absorbing device of this embodiment, the upper column 110 includes a plurality of inward projections 115 in addition to the friction members 111, with the friction members 111 primarily absorbing the impact load during collision and the projections 115 secondarily absorbing the load. As described above, the present invention provides a shock absorbing device for steering columns. The shock absorbing device is provided in the interferential fitting junction between the upper and lower columns of a steering column. The shock absorbing device comprises a plurality of friction members, which are formed on the upper column by a piercing process. In each friction member, the base part is exposed outside the upper column, while the other part is folded down into the upper column to form a friction part. The friction part of each friction member is brought into frictional contact with the external surface of the lower column, thus enlarging the frictional contact area of the shock absorbing device. The shock absorbing device effectively absorbs and relieves shock applied to the steering column in the initial stage of a car collision, thus preventing the shock from being transmitted to a steering wheel in order to protect the driver in a collision. Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims. We Claim : 1. A shock absorbing device provided in an interferential fitting junction between upper and lower columns of a steering column, with the lower column being interferentially fitted into the upper column, and adapted for absorbing and relieving shock applied to the steering column in the initial stage of a collision, comprising: a plurality of friction members formed on the upper column by a piercing process at a positions around the interferential fitting junction, each of said plurality of friction members being folded down into the upper column to be brought into the frictional contact with an external surface of the lower column when the lower column is fitted into the upper column, Wherein each of said plurality of friction members comprises: a base part exposed facing the outside of the upper column; and, a friction part integrally extending from said base part and folded down into the upper column to be brought into close contact with an internal surface of the upper column, said friction part coming into frictional contact with the external surface of the lower column when the lower column is fitted into the upper column. said upper column is inwardly rounded on opposite corners to form a neck having opposingly concave webs to form a narrowed junction between said base part of each of said plurality of friction members and a main body . 2. The shock absorbing device as claimed in claim 1, comprising: a plurality of inward projections formed on the internal surface of the upper column and brought into frictional contact with the external surface of the lower column. 3. A Shock absorbing device substantially as herein described with reference to and as illustrated by the accompanying drawings.

Documents:

3583-del-1997-abstract.pdf

3583-del-1997-assignment.pdf

3583-DEL-1997-Claims.pdf

3583-del-1997-correspondence-others.pdf

3583-del-1997-correspondence-po.pdf

3583-DEL-1997-Description (Complete).pdf

3583-del-1997-drawings.pdf

3583-del-1997-form-1.pdf

3583-del-1997-form-19.pdf

3583-del-1997-form-2.pdf

3583-del-1997-form-4.pdf

3583-del-1997-form-6.pdf

3583-del-1997-petition-137.pdf

3583-del-1997-petition-138.pdf

3583-del-1997-petition-others.pdf