Title of Invention	BREAKAWAY STEERING SYSTEM
Abstract	The invention relates to a breakaway steering system comprising a steering wheel and a steering gearbox connected to each other by means of a steering column & an intermediate link. The intermediate link has an inner shaft and an outer tube joined through a telescopic splined joint. The outer tube is geometrically cut in two steps such that the gap available across the cut splines is slightly more than the shank diameter of the inner shaft but less than the spline diameter and the gap available due to the said cut is sufficient to allow the transverse movement of the splined end during detachment of the inner shaft from the outer tube in the event of a collision. A ramp is also provided at the end of the free space of the outer tube, which facilitates the detachment of the inner shaft from the outer column during collision, and any further movement of the steering gear box is not transmitted towards the passenger compartment.

Title of Invention

BREAKAWAY STEERING SYSTEM

Abstract

The invention relates to a breakaway steering system comprising a steering wheel and a steering gearbox connected to each other by means of a steering column & an intermediate link. The intermediate link has an inner shaft and an outer tube joined through a telescopic splined joint. The outer tube is geometrically cut in two steps such that the gap available across the cut splines is slightly more than the shank diameter of the inner shaft but less than the spline diameter and the gap available due to the said cut is sufficient to allow the transverse movement of the splined end during detachment of the inner shaft from the outer tube in the event of a collision. A ramp is also provided at the end of the free space of the outer tube, which facilitates the detachment of the inner shaft from the outer column during collision, and any further movement of the steering gear box is not transmitted towards the passenger compartment.

Full Text	FORM 2 THE PATENTS ACT 1970 (39 of 1970) & THE PATENTS RULES, 2003 PROVISIONAL SPECIFICATION (See Section 10; rule 13) TITLE OF THE INVENTION BREAKAWAY STEERING COLUMN APPLICANTS TATA MOTORS LIMITED, an Indian company having its registered office at Bombay House, 24 Homi Mody Street, Hutatma Chowk, Mumbai 400 001, Maharashtra, India INVENTOR Vinayak Gogate an Indian national of TATA MOTORS LIMITED, an Indian company having its registered office at Bombay House, 24 Homi Mody Street, Hutatma Chowk, Mumbai 400 001 Maharashtra, India PREAMBLE TO THE DESCRIPTION The following Provisional specification particularly describes the invention and the manner in which it is to be performed. FIELD OF INVENTION This invention relates to break away steering column. Said steering column being connected to a steering gear box. BACKGROUND OF INVENTION Steering intrusions are one of the major contributors for driver injuries in case of the frontal crashes. These intrusions are caused due to transmission of steering gear box movement into the passenger compartment. Conventionally, the steering linkage begins with steering wheel (1) in the passenger compartment. It is mounted on steering column (2). The steering column (2) is connected to the steering gear box (4) through an intermediate link (3). The intermediate link (3) is made of two parts viz. male part (5) and female part (6) joined through telescopic splined joint (8). The splines (details explained in Fig 3 and 4) are followed by free space (7). The joint helps to adjust dimensional variations of the assembly without compromising on torque transmission. It is also helpful in maintaining the linkage during slow speed impacts wherein the longitudinal movements of the steering gear box are on smaller scale. In case of higher longitudinal movements of the steering gear box, the two parts of the intermediate link slides beyond the splined joint and enters the free space (7). Thus it prevents movement of the rear portion of the intermediate shaft and thus controls the steering column intrusion inside the passenger compartment. However, this arrangement is useful only if steering gear box movement is less than the free space. In the event of crash, the steering gear box (4) is pushed backwards. The movement of the steering gear 2 box (4) is transmitted to the one end of steering column (2) through the intermediate link (3). One of the ways to restrict the steering column movement is to break the intermediate link (3) to separate linkage to the steering gear box (4) under higher structural movements, which would occur in the event of crash. This is termed as "break away steering column". Another type of breakaway linkage contains a coupling such that the attachment bolts can allow longitudinal movements through slot provided on one of the attached parts DESCRIPTION OF INVENTION The steering linkage begins with steering wheel in the passenger compartment. It is mounted on steering column (2). The steering column (2) is connected to the steering gear box (4) through an intermediate link (3). The intermediate link (3) is made of two parts viz. male part (5) and female part (6) joined through telescopic splined joint characterized in that the female end (6) is cut longitudinally in two steps (refer Fig 5, 6 and 7). The first cut is provided in such a way that the gap available across the cut splines (12) is slightly more than the spindle diameter beyond the splines (10) but less than the spline diameter (11). This does not allow the splines to disengage during normal course of operation. However allows perpendicular movement of spindle (5) during disengagement. The second cut (13) is such that the gap available is big enough to allow perpendicular movement of the splined end through it during separation. There is a ramp (9) provided at the end of the free gap (7) such that it promotes detatchment of the splined end during its longitudinal movement. It is located in 3 such a way that the male portion of splined joint is completely detached from the female portion. During vehicle crash test, the steering gear box (4) moves forward. It pushes the intermediate link (3) to telescope into one another. Length of the intermediate link is reduced till the splined joint (8) is completely detached. At this point the free end of the moving part of the intermediate link is pushed away by the ram (9) which separates the complete link. With this the intermediate link has broken and any further movement of the steering gear box is not transmitted towards passenger compartment. This is "breakaway design" (refer Fig 12). Dated this 27th day of September 2006 (KARUNA GOLERIA) Of DePENNING & DePENNING 4 TATA MOTORS LIMITED By their Agent and Attorney

Full Text

FORM 2
THE PATENTS ACT 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
PROVISIONAL SPECIFICATION
(See Section 10; rule 13)
TITLE OF THE INVENTION
BREAKAWAY STEERING COLUMN
APPLICANTS
TATA MOTORS LIMITED, an Indian company having its registered office at Bombay House, 24 Homi Mody Street, Hutatma Chowk, Mumbai 400 001, Maharashtra, India
INVENTOR
Vinayak Gogate an Indian national of TATA MOTORS LIMITED, an Indian company having its registered office at Bombay House, 24 Homi Mody Street, Hutatma Chowk, Mumbai 400 001 Maharashtra, India
PREAMBLE TO THE DESCRIPTION
The following Provisional specification particularly describes the invention and the manner in
which it is to be performed.

FIELD OF INVENTION
This invention relates to break away steering column. Said steering column being connected to a steering gear box.
BACKGROUND OF INVENTION
Steering intrusions are one of the major contributors for driver injuries in case of the frontal crashes. These intrusions are caused due to transmission of steering gear box movement into the passenger compartment.
Conventionally, the steering linkage begins with steering wheel (1) in the passenger compartment. It is mounted on steering column (2). The steering column (2) is connected to the steering gear box (4) through an intermediate link (3). The intermediate link (3) is made of two parts viz. male part (5) and female part (6) joined through telescopic splined joint (8). The splines (details explained in Fig 3 and 4) are followed by free space (7). The joint helps to adjust dimensional variations of the assembly without compromising on torque transmission. It is also helpful in maintaining the linkage during slow speed impacts wherein the longitudinal movements of the steering gear box are on smaller scale. In case of higher longitudinal movements of the steering gear box, the two parts of the intermediate link slides beyond the splined joint and enters the free space (7). Thus it prevents movement of the rear portion of the intermediate shaft and thus controls the steering column intrusion inside the passenger compartment. However, this arrangement is useful only if steering gear box movement is less than the free space. In the event of crash, the steering gear box (4) is pushed backwards. The movement of the steering gear
2

box (4) is transmitted to the one end of steering column (2) through the intermediate link (3).
One of the ways to restrict the steering column movement is to break the intermediate link (3) to separate linkage to the steering gear box (4) under higher structural movements, which would occur in the event of crash. This is termed as "break away steering column".
Another type of breakaway linkage contains a coupling such that the attachment bolts can allow longitudinal movements through slot provided on one of the attached parts
DESCRIPTION OF INVENTION
The steering linkage begins with steering wheel in the passenger compartment. It is mounted on steering column (2). The steering column (2) is connected to the steering gear box (4) through an intermediate link (3). The intermediate link (3) is made of two parts viz. male part (5) and female part (6) joined through telescopic splined joint characterized in that the female end (6) is cut longitudinally in two steps (refer Fig 5, 6 and 7). The first cut is provided in such a way that the gap available across the cut splines (12) is slightly more than the spindle diameter beyond the splines (10) but less than the spline diameter (11). This does not allow the splines to disengage during normal course of operation. However allows perpendicular movement of spindle (5) during disengagement. The second cut (13) is such that the gap available is big enough to allow perpendicular movement of the splined end through it during separation. There is a ramp (9) provided at the end of the free gap (7) such that it promotes detatchment of the splined end during its longitudinal movement. It is located in
3

such a way that the male portion of splined joint is completely detached from the female portion.
During vehicle crash test, the steering gear box (4) moves forward. It pushes the intermediate link (3) to telescope into one another. Length of the intermediate link is reduced till the splined joint (8) is completely detached. At this point the free end of the moving part of the intermediate link is pushed away by the ram (9) which separates the complete link. With this the intermediate link has broken and any further movement of the steering gear box is not transmitted towards passenger compartment. This is "breakaway design" (refer Fig 12).
Dated this 27th day of September 2006

(KARUNA GOLERIA) Of DePENNING & DePENNING
4
TATA MOTORS LIMITED By their Agent and Attorney

BREAKAWAY STEERING SYSTEM

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