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

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TITLE OF THE INVENTION
Method of evaluating driveline jerk for vehicle in dynamic condition
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. Shoaib Iqbal, Mr. Yogesh Yelwande & Mr. Santosh Gosavi
all 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 specification particularly describes the invention and the manner
in which it is to be performed


FIELD OF INVENTION
This invention relates to method of evaluating driveline jerk for vehicle in dynamic condition and more particularly to method of evaluating driveline jerk at different locations along the driveline in vehicle driving condition.
BACKGROUND OF INVENTION
In a vehicle, engine is primary source of Torsional vibration, periodic combustion impulses result in rotational speed fluctuations of the crankshaft, ignition and combustion within a cylinder cause a rapid rise in gas pressure and an angular acceleration of the crankshaft, gas compression in the next cylinder causes immediate deceleration. Torque pulsation result in crankshaft torsional vibration and in a way of Power transmission Torsional vibration enters gearbox and is further transmitted to propeller shaft, differentials and finally to passenger cabin via suspension.
High rate of variation in angular acceleration (Torsional vibration) along the driveline results in driveline jerk which is felt by passengers.
Driveline jerk cause horizontal accelerations in the chassis and the passenger compartment, which may lessen comfort and driveability to an unacceptable extent
Comfort is an increasingly important issue when buying a vehicle; to fulfill the customer requirement automobile manufactures are struggling to find method of measurement, evaluation of driveline jerk and refinement of vehicle driveline to reduce power train NVH issues.
Driveline Jerk (angular) is basically rate of change of angular acceleration, that is, the derivative of angular acceleration with respect to time, the second derivative of angular velocity, or the third derivative of angular position.
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In conventional method jerk is measured at aggregate level like on the engine
flywheel at the engine test bed or gears in case gearbox test rig. This only validates
aggregate and component design in terms of producing horizontal acceleration or jerk
phenomenon.
Above method fail to generate the driveline jerk in vehicle condition, though in recent
years development in field of CAE has been done to model the driveline and find the
jerk, but that too cannot be realistic.
OBJECTS OF THIS INVENTION
> The main object of this invention is to provide Method of evaluating in-vehicle
condition driveline jerk for vehicle. This is applicable for both front wheel drive
vehicle and rear wheel drive vehicle.
> The other object of this invention is to provide a method of evaluating driveline jerk in vehicle in dynamic conditions which will be able to give more realistic evaluating conditions than the test rig.
> Another object is to provide a method of evaluating driveline jerk at two different locations simultaneously namely at gearbox output (1), rear axle input (2) incase of rear wheel drive vehicle and at gearbox output (1) and front wheel end(3) in case of front wheel drive, though for calculation purpose data is also acquire at engine output
(4)-
> Yet another object of this invention is to provide a method of evaluating driveline jerk with different power train configuration to investigate the effect of engine, flywheel, clutch, gearbox, end yoke types, propeller shaft/driveshaft, and rear axle on driveline jerk.
> Yet another object of this invention is to find out driveline jerk with respect to engine RPM, which will help us in correlating driveline jerk with other NVH parameters like in-cab noise level, linear acceleration level with reference to engine RPM.
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Another object of this invention is to provide a method of evaluating driveline jerk which is simple and requires less effort and time.
STATEMENT OF INVENTION
Method of evaluating driveline jerk for a vehicle in Dynamic condition comprises of following steps:
a) Identifying the vehicle having front or rear wheel drive on which testing has to be performed;
b) Preparation of flywheel housing(4) with drill al taped as per sensor(5) outer diameter and preparation of fixture for mounting sensor vertically to sense the ring gear (Engine output) RPM;
c) Preparation o! gearbox output yoke &) with to^^'^^^^^^y^^^A^^T
acquiring the torsional vibration data) and after assembling it to the vehicle preparing fixture(7) for mounting sensor vertically to sense the mounted tooth wheel speed (Gear box output) RPM;
d) Preparation of differential input yoke(9) with tooth wheel (scan by sensor(10) for acquiring the torsional vibration data) and after assembling it to the vehicle preparing fixture(l 1) for mounting sensor vertically sense the mounted tooth wheel (rear axle input) RPM;
e) Preparation of fixture(12) for mounting sensor (13) sense the anti lock braking system toner wheel (front wheel end) £PM;
f) Instrumentation of the vehicle for acquiring RfM time history at four location mainly engine output(4), gearbox output(l), axle input2) and front wheel end(3);
g) Collection of data in test track in wide open bottle coasting and tip in-tip out condition in each gear;
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h) Analyzing the collected RPM time history using software tool for angular acceleration, and further differentiating it in different test condition and in different gears which describes the vehicle driveline jerk characteristics ;
Method of evaluating in-vehicle condition driveline jerk for vehicle, wherein said magneto resistive sensor fixture is fitted in such a way so that there is zero relative motion between sensor and mounted tooth wheel for which brackets is attached to flywheel housing, gearbox housing and differential housing so that overall bracket length is minimum and bracket is ribbed for rigidity.
Method of evaluating in-vehicle condition driveline jerk for vehicle, wherein said magneto resistive sensor are placed so that its axis is perpendicular to the tangent of tooth wheel.
Method of evaluating in-vehicle condition driveline jerk for vehicle, wherein instrumentation of the vehicle involves provision of magneto resistive sensors, transistor transistor logic (TTL) converter, laptop connection via fire wire and data acquisition system.
Method of evaluating in-vehicle condition driveline jerk for vehicle, wherein vehicle is tested at wide open throttle, coast down condition and tip in-tip out in each gear. Fine tuning of the power train components may required with the aim to reduce driveline jerk by using results obtained by a method of evaluating in-vehicle condition driveline jerk for both front and rear wheel drive vehicle.
BRIEF DESCRIPTION OF INVENTION
In method of evaluating in-vehicle condition driveline jerk for vehicle, jerk (angular) were measured and mapped at two location of driveline one is gearbox end and other is axle end/front wheel end on the vehicle in different driving events.
This involves following major steps -
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• Vehicle Preparation - Necessary fixtures and brackets are manufactured for sensor mounting. Depending upon the location of measurement the fixtures and brackets are manufactured for each vehicle.
• Vehicle Instrumentation - Test vehicle is instrumented with magneto resistive angular speed measuring sensors to measure the RPM at following locations -
o Engine out (4) (Flywheel / Ring gear) - Jerk at gearbox output and axle
input in evaluated with respect to engine RPM o Gearbox out (1) - to evaluate and map the driveline jerk (angular) at
gearbox out. o Differential input (2) - to capture the driveline jerk which ultimately
passes to passenger cabin through suspension, chassis and body. o Front wheel end (3) - to evaluate and map the progress/status of
driveline jerk at the front wheel end.
• Data Acquisition - Instrumented vehicle is driven in each gear as per devised
test condition to collect the driveline jerk (angular) related data. The test condition are
as follows:
o Wide open throttle in each gear
o Coasting in each gear
o Tip-in Tip-out in each gear
• Data Analysis - The collected data is post processed using software tools to get
the angular acceleration which is further differentiated with respect to time to quantify
the driveline jerk at two locations of driveline. Complete analysis by plotting jerk in
rad/sec3 in Y axis and Engine RPM in X axis for respective dominant orders on
driveline enables to know the driveline jerk and helps to identify the area which needs
the improvement.
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BRIEF DESCRIPTION OF DRAWINGS
Fig 1 shows typical instrumentation for Method of evaluating driveline jerk for a vehicle in dynamic condition
Fig 2 shows fly wheel housing, gear box output yoke, differential input yoke and front wheel end mounted with sensor.
Fig 3 (a) shows raw data for engine flywheel speed (RPM) Vs Time. Fig 3 (b) shows raw data for gearbox output speed (RPM) Vs Time. Fig 3 (c) shows raw data for axle input speed (RPM) Vs Time Fig 3 (d) shows raw data for front wheel end speed (RPM) Vs Time
Figure 4 shows analysis plot for angular acceleration (rad/sec2) Vs time (sec)
for engine output.
Figure 5 shows analysis plot for angular acceleration (rad/sec2) Vs time (sec)
for gearbox output.
Figure 6 shows analysis plot for angular acceleration (rad/sec2) Vs time (sec)
for axle input.
Figure 7 shows analysis plot for angular acceleration (rad/sec2) Vs time (sec)
for front wheel end.
Figure 8 shows analysis plot for Jerk (rad/s3) Vs engine RPM for engine output.
Figure 9 shows analysis plot for Jerk (rad/s3) Vs engine RPM for gearbox output.
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Figure 10 shows analysis plot for Jerk (rad/s3) Vs engine RPM for axle input.
Figure 11 shows analysis plot for Jerk (rad/s3) Vs engine RPM for front wheel end.
DETAILED DESCRIPTION OF INVENTION
Referring now to the drawings wherein the showings are for the purpose of illustrating a preferred embodiment of the invention only, and not for the purpose of limiting the same
Referring to figs 1 to 11, The method of evaluating driveline jerk (angular) for a vehicle in dynamic condition utilizes digital measuring technique which is based on sampling at equidistant angular intervals around the rotating powertrain components which is accomplished by scanning a toothed wheel with a magneto-resistive sensor. The sensor electronic unit generates an angular velocity signal in form of a transistor transistor Logic (TTL) pulse train. The frequency of the pulse train is directly proportional to the angular velocity of the rotating driveline component and the instantaneous angular velocity is calculated by dividing the actual angular spacing of the physical steps between the gear teeth by the elapsed time from one leading edge to the next.
For evaluating driveline jerk (angular) raw data (angular velocity Vs time) were acquired at engine output, gearbox output, axle input and front wheel end.
Method of evaluating driveline jerk (angular) for a vehicle in dynamic condition consists of following steps -
a) Identifying the vehicle having rear wheel drive/front wheel drive on which testing to be performed;
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b) Drilling a tapped hole on a flywheel housing(4) and preparing fixture for mounting sensor(5) vertically on said fly wheel to sense the Engine output RPM;
c) Preparing gear box output yoke(6) with tooth wheel required for scanning by sensor(8) for acquiring torsional vibration data and preparing flxture(7) for mounting sensor(8) on gear box out put yoke mounted tooth wheel vertically to sense the Gear box output RPM;
d) Preparing differential input yoke(9) with tooth wheel required for scanning by sensor(lO) for acquiring torsional vibration data and preparing fixture(ll) for mounting sensor(lO) on differential input yoke(9) vertically to sense the rear propeller shaft RPM;
e) Assembling said gear box output yoke and said differential input yokes on vehicle.
f) Preparation of fixture(12) for mounting sensor(13) to sense the anti lock braking system toner wheel (front wheel end) RPM;
g) Instrumentation of the vehicle by assembling sensors on engine output, gear box output and differential input/front wheel end with the help of said fixtures for driveline jerk basic data collection.
h) Collecting driveline jerk baseline data (angular velocity) in throttle wide open, coasting and tip-in tip-out test condition in each gear;
i) Analyzing the collected torsional vibration data for angular acceleration in time domain, and further differentiating it in time domain to get angular jerk for said test condition. Using software tool for particular event angular jerk in rad/sec3 Vs time in sec and engine speed in rpm Vs time in sec are converted to one curve having X axis engine speed in RPM and Y axis angular jerk in rad/sec3 which is easy to interpret.
For acquiring driveline jerk data at engine output a magneto resistive sensor is mounted to sense the ring gear. For gear box output and differential input, original

universal joint yoke is replaced by a gear toothed wheel having module in-between 0.6 to 2.4 mm and pitch in-between 1.9 mm to 7.7 mm, the actual being dependant upon the diameter of the yoke. For front wheel end a magneto resistive sensor is mounted to sense the antilock braking system toner wheel. Figure 1 shows the various measuring locations to capture the data along with Power train which is required to evaluate driveline jerk.
After toothed gear wheel mounting and sensor mounting bracket fitment, the vehicle instrumentation with respect to sensor positioning, cabling and making data acquisition system ready for data collection, is done. Figure 2 shows mounting details of the sensors.
The data is collected in each gear at following test conditions -
a) Wide open throttle - Vehicle is driven from standstill to maximum speed with clutch engaged, full throttle and no braking.
b) Coast down - Vehicle is driven from maximum speed to standstill in clutch engaged condition, with no throttle and no braking.
c) Tip-in Tip-out - Vehicle is driven to highest responsive vehicle speed (Kmph) and speed is maintain static at that particular speed and than throttle is open (10-15% further) and back to static position in cyclic manner.
After successful data acquisition following analysis is performed -
a) 2D angular velocity analysis Vs time for engine output, gearbox output and axle input location/front wheel end location - This is basically raw data analyzed for particular dominant order. Which is shown clearly in figure-3(a), 3(b), 3(c) & 3(d).
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b) 2D angular acceleration analysis Vs time for gearbox output and axle input location/front wheel end location - This is basically obtain by differentiating angular velocity in time domain for various dominant order. Which is shown clearly in figure-4,5,6 & 7
c) 2D angular jerk analysis Vs time for gearbox output location. This tells the driveline jerk at gearbox output location and is basically obtained by differentiating angular acceleration in time domain. Which is shown clearly in figure-8
d) 2D angular jerk analysis Vs time for axle input/front wheel end location. This tells the driveline jerk at axle input/front wheel location and is basically obtained by differentiating angular acceleration in time domain. Which is shown clearly in figure-9 & 10
e) 2D angular jerk analysis Vs engine RPM for gearbox output and axle input/front wheel end location. This tells the driveline jerk magnitude and direction (+clockwise and - anticlockwise) over entire Engine speed for particular dominant order. Which is shown clearly in figure-11, 12 & 13.
Analyzed data is then compared between gearbox and axle input/front wheel end measurement location to compare the angular jerk at two location of driveline. These results are then compared against target Benchmark vehicles for power train NVH refinement.
Analyzed data/result helps to identify the area which needs refinement to reduce
driveline jerk.
Benefits of proposed method:
1) As the current driveline jerk (angular) mapping is done simultaneously at two location of driveline i.e. gearbox output(2) and axle input(3)/front wheel
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end(4), there-by we can analyze the flow of driveline jerk from gearbox output to differential input/front wheel end and thus the problematic area can be identified. 2) In proposed method the measurements are performed on the vehicle, which helps to capture the real performance of the vehicle.
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WE CLAIM
1. A method of evaluating driveline jerk of a vehicle comprising the steps of:
identifying the vehicle having rear wheel drive/front wheel drive on which
driveline jerk evaluation is to be performed;
preparing a flywheel housing, a gearbox output yoke and a differential input yoke and various fixtures on said flywheel housing, gearbox output yoke and differential input yoke for mounting a engine output sensor, a gearbox output sensor and a rear propeller shaft sensor respectively for obtaining various RPMs at these locations;
assembling said gear box output yoke and said differential input yoke on said vehicle;
preparing a fixture for mounting anti-lock braking system sensor to sense the anti lock braking system toner wheel (front wheel end) RPM;
performing instrumentation and collecting driveline jerk baseline data in various test conditions;
analyzing collected torsional vibration data for angular acceleration in time domain, and further differentiating it in time domain to get angular jerk for respective test conditions;
comparing said analyzed data between gearbox and axle input/front wheel end measurement location to compare the angular jerk at two location of the driveline.
2. The method as claimed in claim 1, wherein a tapped hole is drilled on said
flywheel housing and said engine output sensor is mounted vertically on said fly
wheel.
3. The method as claimed in claim 1, wherein said gearbox output yoke and input
yoke comprises tooth wheel having a module of 0.6 to 2.4 mm and a pitch of 1.9 mm
to 7.7 mm for scanning by sensor for acquiring torsional vibration data.
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4. The method as claimed in claim 1, wherein said gearbox output sensor is mounted vertically on said tooth wheel of said gear box output yoke.
5. The method as claimed in claim 1, wherein said rear propeller shaft sensor is mounted vertically on said tooth wheel of said differential input yoke.
6. The method as claimed in claim 1, wherein said engine output sensor, gearbox output sensor, rear propeller shaft sensor and anti-lock braking system sensor are magneto resistive sensors.
7. The method as claimed in claim 1, wherein torsional vibration data is collected in test conditions chosen from Wide open throttle condition, Coast down condition and Tip-in Tip-out condition.
8. The method as claimed in claim 7, wherein in wide open throttle condition said vehicle is driven from standstill to maximum speed with clutch engaged, full throttle and no braking.
9. The method as claimed in claim 7, wherein in coast down condition said vehicle is driven from maximum speed to standstill in clutch engaged condition, with no throttle and no brakmg,
10. The method as claimed in claim 7, wherein in tip-in tip-out condition said vehicle is driven to highest responsive vehicle speed, said speed is maintained static and then throttle is open and brought back to static position in cyclic manner.
11. A method of evaluating driveline jerk of a vehicle as hereinabove described with reference to the accompanying drawings.
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12. A system for performing the method of evaluating the driveline jerk of a vehicle as claimed in the preceding claims.
Dated this 16th day of March 2009
TATA MOTORS LIMITED By their Agent & Attorney

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Karuna Goleria of DePENNING & DePENNING