FORM 2
THE PATENTS ACT 1970
(39 of 1970)
&
THE PATENTS RULES, 2003


PROVISIONAL SPECIFICATION
(See Section 10; rule 13)
TITLE OF THE INVENTION Alternative methodology for Installing Steering Angle Sensor at the Steering column
for Electronic Stability Control
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
Jayachandran Duraisamy and Singh Rajnish B
both 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


FIELD OF INVENTION
The present invention relates to Interfacing of Steering Angle Senor (SAS) into steering column for Electronic Stability Control (ESC) in automotive domain.
BACKGROUND OF INVENTION:
With the innovation of Electronic Stability Control the need has arisen for reliable integration of steering angle sensor into steering column in automotive vehicles.
Electronic Stability System controls the individual wheel brakes to help the driver maintain control of the vehicle during extreme maneuvers by keeping the vehicle headed in the direction the driver is steering even when the vehicle nears or reaches the limits of the road traction. Typically ESC system requires "Yaw" and "steering angle" input apart from four wheel speed sensors signal to control the stability of the vehicle. To feed the steering angle signal to ESC system, the steering angle sensor to be installed at the steering column. The place where the sensor to be installed must be selected in such way that only the turning angle of the steering wheel is measured there, without any superimposed secondary measurements. The existing method need of shaft adapter, sensor mounting bracket and it has to be fixed to existing bracket enabling sensor to always be correctly aligned to steering shaft and complex assembly process.
As conventional technology of the rudder sensor which generates angle of rotation of the steering system of a car, the art currently indicated in JP,2000-283704,A, JP,2000-283705,A, etc., a rudder sensor is built into a rudder sensor fixture rotating connector device, and is allocated near the steering wheel. However, the rudder sensor in the conventional technology mentioned above has accomplished the composition allocated near the steering wheel in the state where it included in the rudder sensor fixture rotating connector device, and is dramatically difficult for the allocating a rudder sensor near the steering mechanism constitutionally. The problem that restrictions arise is also in
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arrangement of the other apparatus of the steering wheel circumference by allocating a rudder sensor near the steering wheel.
The proposed methodology talks about an alternate approach for installation of SAS at the steering column with much lesser development, process control, integration cost and easy assembly process.
OBJECTS OF INVENTION:
The main object of invention is to ensure the accuracy and reliability of the steering angle signal to ESP to control the stability of the vehicle by interfacing SAS at the steering column with a less no of child part, stringent assembly process and easy replacement of SAS in field. This approach does not require a shaft adapter, sensor mounting bracket and welding process of sensor mounting bracket into steering shaft-
BRIEF DESCRIPTION OF INVENTION:
The existing methodology of SAS (Fig lc) interfacing is near at the Universal Joint (UJ) of the steering column. This method need of shaft adapter (Fig la), sensor mounting bracket (Fig lb) and it has to be fixed to existing bracket enabling sensor to always be correctly aligned to steering shaft. This method has more no of child parts, stringent process control will result in cost in terms of development and assembly process, Also in Service, rack and pinion to be removed to replace the sensor; It will affect the steering geometry. Hence an alternate methodology is proposed which significantly reduces the no of child parts, stringent process control, complex assembly process and reduces the SAS replacement time without degrading the accuracy and reliability of the steering angle signal to ESC.
The invention proposes a new methodology of interfacing SAS at the steering column to generate the SAS signal to ESC. In this approach SAS (fig 2h) is mounted in between combination switch and clock spring (Fig 2d). Clock spring (Fig 2g) has stationary part and
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rotary part; the rotary part of the clock spring is designed in such way to rotate the SAS rotary part. Typically clock spring rotary part is interfaced with steering wheel (fig 2c) for AIRBAG circuits. When steering wheel rotates clock spring rotary part will rotate thus by SAS rotary part will rotate and generates the steering angle signal to ESC. By this approach only the turning angle of the steering wheel is measured as required by the ESC system. So, by this approach the requirement of ESC system is met without need of shaft adapter, sensor mounting bracket, welding process of sensor mounting bracket into steering shaft and eliminates the need of rack and pinion removal while replacing the SAS.
BRIEF DESCRIPTION OF DRAWINGS:
Figure 1 shows the existing methodologies of SAS interfacing is near at the Universal Joint (UJ) of the steering column.
Figure 2 shows the new methodology of interfacing SAS in between combination switch and clock spring.
DETAILED DESCRIPTION OF INVENTION:
The focus of proposed methodology is to ensure the accuracy and reliable of the steering angle signal to ESP to control the stability of the vehicle by interfacing SAS at the steering column with a less no of child part, stringent assembly process and easy replacement of SAS in field.
Typically ESC system requires "Yaw" and "steering angle" input apart from four wheel speed sensors signal to control the stability of the vehicle. To feed the steering angle signal to ESC system, the steering angle sensor to be installed at the steering column. The place where the sensor to be installed must be selected in such way that only the turning angle of the steering wheel is measured there, without any superimposed secondary measurements.
To meet the above requirements following could be possible approaches.


Approach 1: As shown in the figure 1, SAS (Fig lc) is mounted near at the universal joint of the steering column (Fig Id). In this approach, shaft adapter (Fig la) need to design to interface with sensor rotary hub. And it's to be installed over the rotary part of the steering column. Also this approach requires sensor mounting bracket (Fig lb) required to mount sensor and fix position relative to steering shaft. Typically the sensor mounting bracket to be fixed to existing bracket to enable sensor is always be aligned to steering shaft.
An alternate methodology is proposed to interface the SAS (Fig 2h) in between combination switch and clock spring (fig 2d). Clock spring (Fig 2g) has stationary part and rotary part; the rotary part of the clock spring is designed in such way to rotate the SAS rotary part. Typically clock spring rotary part is interfaced with steering wheel for AIRBAG circuits. When steering wheel (Fig 2c) rotates clock spring rotary part will rotate thus by SAS rotary part will rotate and generates the steering angle signal to ESC. By this approach only the turning angle of the steering wheel is measured as required by the ESC system.
So, in this proposed approach all the ESC system requirements are met without any comprises with accuracy and reliable of the SAS signal with elimination of dedicated shaft adapter, sensor mounting bracket, welding process of sensor mounting bracket into steering shaft and need of rack and pinion removal while replacing the SAS.
Existing method of SAS interfacing at the steering column
Existing methodologies of interfacing SAS at the steering column for ESC system as shown in Figure 1 illustrates that::
• Shaft adapter need to design to interface with sensor rotary hub. And it's to be installed over the rotary part of the steering column.


• Sensor mounting bracket required to mount sensor and fix position relative to steering shaft. Typically the sensor mounting bracket to be fixed to existing bracket to enable sensor is always be aligned to steering shaft.
• Complex assembly sequence process to mount the sensor.
As shown in the drawing clock spring rotary part connector engaged with steering wheel armature for airbag circuit. The clock spring rotary part is engaged with SAS rotary part. When steering rotates, clock spring rotary part will rotate there by SAS rotary part rotates and generates the SAS signal to ESP system.
Detail of SAS mounting feature in combination switch:
Alternative methodologies of interfacing SAS at the steering column for ESC system as shown in Figure 2 illustrates that::
• This proposed methodology requires the rotary part of the clock spring to be designed to rotate the SAS rotary part.
• Combination central housing (Fig 2i) should have SAS mounting feature.
• This proposed methodology results in elimination of This proposed methodology results in elimination of a complex SAS assembly process, additional shaft adapter, sensor mounting bracket, welding process of sensor mounting bracket into steering shaft, and need of rack and pinion removal while replacing the SAS in field.
Advantages:
a. The proposed alternative methodology helps to meet ESC system
requirements by installing the SAS in between combination switch and clock
spring.
b. This proposed methodology requires the rotary part of the clock spring to be
designed to rotate the SAS rotary part. Results in lowest integration cost and
effort without compromising on accuracy and reliable of the SAS signal.

c. This proposed methodology results in elimination of a complex SAS assembly process, additional shaft adapter, sensor mounting bracket, welding process of sensor mounting bracket into steering shaft, and need of rack and pinion removal while replacing the SAS in field.
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 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 insofar as they come within the scope of the invention as claimed or the equivalents thereof.
Dated this 31st day of March 2009
TATA MOTORS LIMITED By their Agent & Attorney

Karuna Goleria of DePENNING & DePENNING