Title of Invention

"AN IMPROVED COLLAPSIBLE STEERING COLUMN ASSEMBLY"

Abstract

This invention provides an improved collapsible steering column assembly for automobiles using energy absorbing column jacket. The characteristic features of the invention resides in an energy-absorbing column jacket (EA Jacket) to which upper bracket and lower bracket are fixed. The said energy absorbing column jacket, consisting of sheet metal as base material, having strip type construction on it's circumference at desired places such that when the driver hits the steering wheel at the time of collision, the impact load is transferred to the capsules, which disengage from upper bracket and thereafter the strip type construction on energy absorbing column jacket deforms and absorbs the impact load / energy, thereby collapsing the steering column.

Full Text

This invention relates to an improved collapsible steering column assembly in automobiles. More particularly, using energy absorbing column jacket to absorb the impact load / energy at the time of collision. BACKGROUND OF THE INVENTION: Conventionally the collapsible column consists of Column Jacket assembly (Cl), Steering shaft assembly (C2) and Intermediate shaft assembly (C3), as shown in Fig 1-b. of the accompanying drawings. The conventional column Jacket assembly (Cl) is the outer part of the collapsible column which provides support to the steering shaft assembly (C2) and on which steering lock and ignition switch are mounted (not shown). The conventional column jacket assembly (Cl) comprises an outer pipe (I), upper bracket (2), inner pipe (2), lower bracket (3), steel balls retained in a plastic retainer called ball retainer (6), and are press fitted between the inner pipe (4) and outer pipe (1) so as to ensure the desired sliding load. Size of the balls decides the interference load between said outer and inner pipes and thereby determines the collapsing load of the Column jacket assembly. During collision, the impact load is transferred to the said outer pipe (I) from the steering wheel (SW), which starts sliding over said inner pipe (4). During this process the steel balls roll over the contact surface of said inner and outer pipe and thereby absorbing the impact energy. The capsule (5) is a part fitted on the upper bracket (2) of Column jacket assembly (Cl) and is in contact with the vehicle body after the column is mounted with the help of bolts (B) (not shown). Normally, two Capsules (5) made of aluminum are used in one steering column assembly. Each capsule has 4 small holes (hi, h2, h3, h4) and similar matching holes (hi, h2, H3, h4) prime are there on the bracket (2). Plastic resin is injected into said holes (hi, h2, h3, h4) putting two capsules (5) and bracket (2) together, thereby forming plastic shear pins (pi, p2, p8), which shear off at a particular load (usually 100-200 Kgf). When the driver hits the steering wheel these shear pins break off along with the shear pins of shaft assembly and the column jacket assembly slides down away from the driver leaving the capsules alone mounted on the vehicle body (see Fig- 3). The disadvantages of this column jacket assembly are as follows: the design is expensive; as it has critical parts like ball retainer, steel balls, two pipes and other special assembly processes production cycle time is more some times it is difficult to achieve large collapse stroke with conventional collapsible column due to insufficient space on the vehicle The object of the instant invention is to obviate the above disadvantages and to provide the collapsible column at low cost, lightweight and easy to adopt in limited space in vehicles. To achieve the said objectives, this invention provides an improved collapsible steering column assembly comprising. Column jacket assembly, mounted on the vehicle, steering shaft assembly being housed in said column jacket assembly for steering the vehicle characterized in that an energy absorbing column jacket consisting of sheet metal as base material, having strip type construction on it's circumference Brief Description of the Accompanying Drawings: The invention will now be described with reference to the accompanying drawings Figures la shows the conventional steering column fitted in a passenger vehicle. Figure Ib shows the construction of conventional collapsible steering column assembly. Figure 2 shows the conventional column jacket assembly Figure 3 shows the conventional capsule in column jacket assembly. Figure 4 shows column jacket, according to this invention. Figure 5 shows the working of energy absorbing column jacket, according to this invention. Figure 6 shows the improved collapsible steering column, according to this invention. Detailed description Figure la, Ib, 2 & 3 have been described under the heading 'background' along with their disadvantages. Figure 4 shows the improved column jacket assembly (Cl-a). It may be seen that strip type construction (S), having at least four strips, is provided on the circumference of energy absorbing column jacket (la) at desired places, which eliminates the use of steel balls, ball retainer (6) and lower pipe (4) as used in the conventional column jacket assembly (Cl). Lower bracket (3) is fixed to energy absorbing column jacket (la) at one end. An upper bracket (2) is fixed to said energy absorbing column jacket (la) at required place. The capsules (5) are provided in the said upper bracket (2). The working of energy absorbing column jacket (la) is shown in figure 5. When the driver hits the steering wheel at the time of collision, the impact load is transferred to capsules (5), which disengages from upper bracket (2) and thereafter the strip type construction (S) on energy absorbing column jacket (la) deforms and absorbs the impact load/ energy, thereby collapsing the steering column. In figure 5, the strip type construction (S) on energy absorbing column jacket (la) before and after the impact is shown. This energy absorbing column jacket (la) eliminates the use of steel balls, ball retainer (6) and lower pipe (4) as used in conventional collapsible steering column, making the product economical, light in weight and suitable to fit in limited space on automobiles. Figure 6 shows an improved collapsible steering column assembly, according to this invention. Item (la) shows the energy absorbing column jacket in improved column jacket assembly (Cl-a). Item (3) shows the lower bracket connected to one end of energy absorbing column jacket (la), (2) shows the upper bracket fixed to said column jacket at desired place, (5) shows capsules. (C2) shows the steering shaft assembly and (C3) shows the intermediate shaft assembly. Advantages of the instant invention: Low cost Light in weight Easy to use with in limited space on the automobiles We claim: 1. An improved collapsible steering column assembly comprising- column jacket assembly, mounted on the vehicle, steering shaft assembly being housed in said column jacket assembly for steering the vehicle characterized in that an energy absorbing column jacket consisting of sheet metal as base material, having strip type construction on it's circumference at desired places such that when the driver hits the steering wheel at the time of collision, the impact load is transferred to the capsules, which disengage from upper bracket and thereafter the strip type construction on energy absorbing column jacket deforms and absorbs the impact load / energy, thereby collapsing the steering column. 2. An improved collapsible steering column assembly as claimed in claim 1, where in the said strip type construction on energy absorbing column jacket is made by removing the material from column jacket. 3. An improved collapsible steering column assembly as claimed in claim 1, where in the said strip type construction on energy absorbing column jacket is made by joining strips consisting of sheet metal as base material. 4. An improved collapsible steering column assembly substantially as herein described with reference to figures 4 to 6 of the accompanying drawings

Documents:

656-del-2004-abstract.pdf

656-del-2004-claims.pdf

656-del-2004-correspondence-others.pdf

656-del-2004-correspondence-po.pdf

656-del-2004-description (complete).pdf

656-del-2004-drawings.pdf

656-del-2004-form-1.pdf

656-del-2004-form-19.pdf

656-del-2004-form-2.pdf

656-del-2004-form-3.pdf

656-del-2004-gpa.pdf