FORM 2
THE PATENTS ACT 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
(See Section 10; rule 13)
TITLE OF THE INVENTION A test setup for prediction of Abrasive Wear Resistance of Steering Wheels due to Human Sweat and method of testing thereof


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
Mr. Hari Srinivas Babu Aggarapu , and Mr.Manqj S. Walkikar 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 particularly describes the invention and the manner in
which it is to be performed.

FIELD OF INVENTION
This invention relates generally to accelerated test procedure of Automotive Steering wheels and more particularly to abrasion resistance test methodology of steering wheels due to human sweat.
BACKGROUND OF INVENTION
The main function of a steering wheel is to apply effort to steer the vehicle. Steering wheel mainly consists of a rim, spokes for supporting the ring portion and a horn pad. Steering wheel design/selection basically depends on:
a. Ease to perform maneuvering.
b. Space available in the cabin interior.
c. Comfort / Ergonomics/ Aesthetics.
Generally, Steering wheel diameter varies between 400 - 450 mm for passenger vehicles & 500 ~ 550 mm for commercial vehicles. Additionally, steering wheel which is always in contact with driver's hand while the vehicle is running must satisfy the following requirements:
1. High endurance life along with integrated safety features.
2. Good steering feel.
3. Good appearance.
4. Good wear Resistance etc.
In relation to the above desirable properties from a Steering wheel, various validation procedures have been formulated for validation of different designs of steering wheels to achieve higher level of safety & aesthetic considerations (as informed in U.S. Pat. No. 4,567,217 & U.S. Pat. No. 4,758,470 etc). Due to constant touch of steering wheel to drivers hand, surface peeling is observed on many steering wheels due to which it becomes difficult during driving and also affects aesthetic looks over a long period of usage.This is mainly due to constant

friction between drivers' hand grip and steering wheel rim & subsequent effect of environmental condition /humidity factor on steering wheel. The heat transfer through the body to which it contacts i.e. steering wheel in this case is in the form of sweat evaporation. This contains several chemical ingredients which affects foam/leather wrapping on steering wheel rim. However, in the past, no test procedures are available to simulate the effect of human sweat through palms of hand on steering wheel rim. The present invention relates to development a test procedure to simulate the effect of human sweat on steering wheel rim, as a part of validation of subject test component.
OBJECTS OF INVENTION
1) The main object of this invention is to develop a testing procedure that is capable of simulating the effect of human sweat on the durability life of steering wheels in actual usage conditions.
2) Yet another object of this invention is to provide an apparatus for testing of Steering wheels used in automotive applications under the effect of human sweat.
3) Yet another object of this invention is to compare the life of various designs of steering wheels to the effect of human sweat due to absorption of moisture from human palms.
4) Yet another object of this invention is to establish minimum number of Abrasive wear cycles required to be satisfied by a steering wheel for the aesthetic and/safe operation of the vehicle .
BRIEF DESCRIPTION OF DRAWING
Fig. 1 is a Test set-up of Steering Wheel Abrasion Resistance Test using human Sweat.

DETAILED DESCRIPTION OF INVENTION
The subject steering wheel (1) under test shall be mounted on a suitable fixture (2) as indicated in Figure T. A friction member, such as a strap (4), for acting as a rubbing element is passing over the steering wheel and surface of the strap is in contact with the surface of the steering wheel. One end of the strap is connected to a dead weight (5) of approximately 2kg with the other end connected to a reciprocating cylinder (3). The rubbing action is activated by connecting the cylinder to a pneumatic source capable of reciprocating 2 kg load by means of a controller .The controller is provided with PLC based system that not only controls the required stroke of the cylinder but also counts the no. of cycles. Steering wheel (1) shall be subjected to the following test conditions. A nozzle is located near the steering wheel to spray artificial sweat solution on the steering wheel area where the rubbing action is taken place. The nozzle connected to a tank filled with artificial sweat solution.
TEST METHOD
The wheel is pre-conditioned by subjecting it to a temperature of 90°C for 72 hrs followed by -40°c for 24hrs and the test is conducted at ambient temperature. The temperature soaking is done to simulate the temperatures achieved by steering wheel during noon of the day. The steering wheel surface is wetted after every 1 hour using an artificial sweat solution. The wetting period is selected based on the interaction of drivers hand with the steering wheel to simulate the usage of the vehicle. Due to the weight acting on the strap end, strap rubs against the wheel surface. The Coefficient of friction (u) of the strap is preferably equal to or more than 0.8 in-line with the co-efficient of friction generated by the interaction of the drivers' hand with the steering wheel surface. To achieve actual condition a minimum of 50% of the wheel rim circumference should be overlap with strap as it is observed that on an average the holding circumference of the steering wheel is

only 40-50 % of the diameter of the wheel with the human hand holding width ranging from 80 100 mm . Accordingly, the width of the rubbing strap was chosen as 80 to 100 mm with the stroke maintained as 200 mm . The cylinder is actuated 13 to 15 cycles per minute with each TO and FRO stroke of cylinder counted as T cycle .
PROCEDURE FOR MAKING ARTIFICIAL SWEAT SOLUTION
Analyses of metabolites in human sweat have been performed in various clinical studies. Sweat secreted through palms of hand of a human body mainly contains sodium chloride (NaCl), lactic acid, acetic acid. In addition, it contains nitrogen metabolites. Ingredients of these sweat in required contents were collected to make 10 liter artificial sweat solution. With these ingredients, artificial sweat solution was made in laboratory with water as base solution. Refer table 1 below for preparation of 10 liter artificial sweat solution.

Ingredients Quantity
NaCl 200 gm
NH4CI 175 gm
Lactic acid 35 ml
Acetic acid 15 ml
Table 1 These solutions were mixed with proportionate amount of water.PH value of this solution was measured using PH meter. Depending on the nature of this prepared solution, PH value was maintained very near to PH value of human sweat (i.e. 4.7) by adding suitable quantity of Sodium hydroxide (NaOH).
Level of Acceptance : After the test is completed for specified number of cycles as per Table number 2 below, the steering wheel tested area shall not show any signs of cracks/Attrition/ material peel-off as compared to non-tested area. However, smoothening/polishing of the rubbed area shall be allowed.

Design of Steering Wheel Number of Cycles (min)
Poly Propylene (PP) steering Wheel 3.0 Lakhs
Poly Urethane (PU) steering wheel 1.0 Lakhs
Poly Urethane (PU) steering wheel with Synthetic/Artificial leather 1.0 Lakhs
Poly Urethane (PU) steering wheel with Genuine (animal) Leather 3.0 Lakhs
Table 2

WE CLAIM
1. An apparatus for testing abrasion resistance of automotive steering wheels
due to human sweat comprising:
a steering wheel mountable fixture on which the steering wheel under test is mounted;
a friction element provided to overlap and oscillate over the circumference of said steering wheel to facilitate a rubbing action; and
an artificial sweat solution spraying means located proximal to said steering wheel to spray artificial sweat solution on the portion of said steering wheel where the friction element oscillates.
2. The apparatus as claimed in claim 1, wherein one end of said friction element is connected to a dead weight and the other end is connected to a reciprocating cylinder.
3. The apparatus as claimed in claim 2, wherein said dead weight is approximately 2 kg.
4. The apparatus as claimed in claims 2, wherein a controller is provided to control the pneumatic reciprocating of said cylinder, said controller is further provided with a PLC based system that controls the required stroke and the reciprocating cycles of said cylinder.
5. The apparatus as claimed in claim 1, wherein said artificial sweat solution spraying means is preferably a nozzle connected to a tank filled with artificial sweat solution.
6. The apparatus as claimed in claim 1, wherein the coefficient of friction (u) of the frictional element is preferably equal to or more than 0.8.

7. The apparatus as claimed in claim 1, wherein at least 50% of the steering wheel circumference overlaps with said friction element.
8. The apparatus as claimed in claim 1 and 2, wherein the width of the friction element is 80 to 100 mm and the cylinder stroke is maintained at 200 mm .
9. A method for testing abrasion resistance of automotive steering wheels due to human sweat comprising the steps of:
mounting said steering wheel on a test fixture;
passing a friction element over the circumference of said steering wheel to facilitate a rubbing action, such that, one end of said friction element is connected to a dead weight and the other end is connected to a reciprocating cylinder;
pneumatically actuating said reciprocating cylinder to facilitate rubbing action of said friction element over the circumference of said steering wheel
wetting said steering wheel circumference with an artificial sweat solution.
10. The method as claimed in claim 9, wherein said artificial sweat solution is sprayed over said steering wheel circumference every one hour.
11. The method as claimed in claim 9, wherein said cylinder is actuated 13 to 15 cycles per minute.
12. The method as claimed in claim 9, wherein the artificial sweat solution is maintained with a pH-value of about 4.7.
13. An apparatus for testing abrasion resistance of automotive steering wheels due to human sweat as hereinabove described with reference to the accompanying drawings.

14. A method for testing abrasion resistance of automotive steering wheels due to human sweat as hereinabove described with reference to the accompanying drawings.
Dated this 24th day of February 2009