FORM 2
THE PATENTS ACT 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
(See Section 10; rule 13)


TITLE OF THE INVENTION Steering Wheel Integrated With Safety Feature
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
INVENTORS
Ajit Gokhale and Karimullah Shaikh
Both are Indian Nationals
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 specification describes the invention and the manner in which it
is tn he nerfnrmerl.


FIELD OF INVENTION
This invention relates to safety system of automobile and more particularly it relates to the steering wheel with integrated safety feature of an automobile.
BACKGROUND OF INVENTION
In the case of automotive safety, the steering wheel is one of the major causes for bodily injury to driver in the event of a crash. This is on account of stiffness of the steering wheel structure which produces forces between the driver & the steering system.
Conventionally the steering wheel is made stiff in order to avoid excessive vibration when the engine is running slowly which is a potential irritant to the driver. However such stiff steering wheel structure is not compliant with human body when it hits it during crash and results into injuries. In order to reduce the risk of bodily injury to the human body, the steering wheel is required to be softer such that said steering wheel can produce lower reaction forces during the impact. Therefore it is desirable that the steering wheel spokes deform, absorb energy & provide soft cushioning to the body. It is therefore necessary to provide weaknesses in the steering wheel spokes to promote & control the energy absorption during impact. The invention comprises an improvement in the invention claimed in the specification of the main Indian patent applied for under IPA. No. 461/mum/2008.
OBJECTS OF INVENTION
The main object of the present invention is to provide a steering wheel with integrated safety feature of an automobile.
Another object of the present invention is to provide a steering wheel with integrated safety feature of an automobile which vary the stiffness of a steering wheel to minimize the bodily injury to an occupant in the event of crash without affecting its vibration stability.

2

STATEMENT OF INVENTION
Accordingly the present invention discloses a steering wheel with safety feature comprising
a hub;
a rim;
plurality of horizontal spokes and vertical spokes connecting the said rim to the said hub; wherein
said vertical spokes having bent configuration and comprises plurality of groove portions for reducing the stiffness of the said steering wheel configured to bend downwards at weak zone under the influence of external force;
and at least one predetermined weakened portion on said horizontal spokes.
BRIEF DESCRIPTION OF DRAWINGS
In accordance to the present invention,
Figure-01 shows the top view of a steering wheel
Figure-02 shows side view of the steering wheel
Figure-03 shows the top view of the steering wheel in accordance with the present
invention
Figure-04 shows the side view of the steering wheel in accordance with the present
invention
BRIEF DESCRIPTION OF INVENTION
In accordance with the present invention, the steering wheel with integrated safety feature comprises hub (c.2) which is provided for connecting the steering wheel to the steering column with the help of fasteners, rim (c.l) for providing input to turn the steering system, plurality of horizontal spokes (c.3) and vertical spokes (c.4) for connecting the said rim (c.l) to the said hub (c.2) wherein said vertical spokes comprise at least three weak zone for reducing the stiffness of the steering wheel. The said weak zone is in the form of groove. Said horizontal spoke comprises at

least one predetermined weakened portion (C5.1) on either side and said vertical spokes comprises at least three grooves (C5.2, C5.3, C5.4) for absorbing energy during impact.
DETAILED DESCRIPTION OF INVENTION
In accordance with the present invention, steering wheel with safety feature comprises rim (C.l), hub (C.2), plurality of horizontal spokes (C.3) and plurality of vertical spokes (C.4). Said spokes join the said rim to said hub to translate the movement of said rim to the said hub which is connected with the input shaft of the steering column. Said vertical spoke of said steering has at least two bent at locations (C.5 & C.6),
Wherein said horizontal and vertical spoke comprises rectangular cross section. Said horizontal spoke comprises at least one predetermined weakened portion (C5.1) on either side and said vertical spokes comprises at least three grooves ( C5.2, C5.3, C5.4) for absorbing energy during impact.
Wherein said predetermined weakened portions are provided at junction where said spokes join the said hub, at first bend (C5), at second bend (C6) and at a junction where said spoke join the said rim.
The thickness (T1.2) of said spoke at weakened portion is reduced to 0.325 to 0.55 times the original thickness (Tl.l) of the said spokes. Such as
T1.2 = 0.325 to 0.55 times Tl.l
The extent or length (El.l) for the said weakened portion of horizontal spoke is equal to or greater than 0.2 times the straight spoke length (El.2). Such as
El.l>0.2xE1.2
The said vertical spokes comprises at least three grooves (C5.2, C5.3 & C5.4) which are provided to absorb energy at these location in case of an impact.

The thickness (T2.2) of said vertical spoke at the said groove (C5.2) is half the thickness (T2.1) of the said vertical spoke. Such that the ratio;
T2.2 = 0.5xT2.1 The extent or length (E2.1) of said groove ( C5.2) of said vertical spoke is equal to or greater than 6 times the thickness (T2.2) of said spoke at said groove (C5.2). Such that
E2.1>6xT2.2
The thickness (T3.2) of said vertical spoke at the said groove (C.5.3) is half the thickness (T3.1) of the said vertical spoke. Such that the ratio;
T3.2=0.5xT3.1
The extent or length (E3.1) of said groove (C5.3) of said vertical spoke is equal to or greater than 6 times the thickness (T3.2) of said spoke at said groove (C5.3). Such that;
E3.1>6xT3.2
The thickness (T4.2) of said vertical spoke at the said groove (C.5.4) is one third of the thickness (T4.1) of the said vertical spoke. Such that the ratio
T4.2 = 0.3xT4.1
The extent or length (E4.1) of said groove (C5.4) of said vertical spoke is equal to or greater than 7 times the thickness (T4.2) of said spoke at said groove (C5.4). Such that;
E4.1>7xT4.2
The foregoing description is a specific embodiment of the present invention. It should be appreciated that this embodiment is described for purpose of illustration only, and that numerous alterations and modifications and combinations may be practiced by those skilled in the art without departing from the spirit and scope of the invention. It is intended that all such modifications and alterations be included

WE CLAIM
1. Steering wheel with safety feature comprising
a hub;
a rim;
plurality of horizontal spokes and vertical spokes connecting the said rim to the said hub; wherein
said vertical spokes having bent configuration and comprises plurality of groove portions for reducing the stiffness of the said steering wheel configured to bend downwards at weak zone under the influence of external force;
and at least one predetermined weakened portion on said horizontal spokes.
2. Steering wheel as claimed in claim 1, wherein said vertical spokes has at least two bends.
3. Steering wheel as claimed in claim 1, wherein said horizontal and vertical spoke comprises of rectangular cross section.
4. Steering wheel as claimed in claim 1, wherein said vertical spokes comprise at least three groove portions provided one at the junction of spoke and hub joint and one at each bends.
5. Steering wheel as claimed in claim 1, wherein the thickness of weakened portion of said horizontal spokes is between 0.325 to 0.55 times of its original thickness and length of weakened portion is equal to or greater than 0.2 times the straight spoke length of said horizontal spoke.
6. Steering wheel as claimed in claim 1, wherein the thickness of groove portion at the bends of said vertical spokes is 0.5 times of its original thickness and length of said groove portion is equal to or greater than 6 times of original thickness of said spokes at bends.
7 14 AUG 2009

7. Steering wheel as claimed in claim 1, wherein the thickness of groove portion at the junction of said vertical spoke and hub is 0.3 times of its original thickness and length of said groove portion is equal to or greater than 7 times the thickness of said groove portion at junction of vertical spoke and hub.
8. Steering wheel with safety feature is substantially as described in the description and as illustrated in the accompanying figures.

Karuna Goleria of DePENNING & DePENNING

TATA MOTORS LIMITED By their Agent & Attorney