FORM 2
THE PATENTS ACT 1970
(39 of 1970)
AND
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
(See Section 10; rule 13)
TITLE OF INVENTION
Method Of Testing In-Vehicle Condition Power Train Torsional Vibration For Vehicle
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. Santosh Gosavi
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
REAMBLE 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 in vehicle condition method of testing power train torsional vibrations for vehicles and more particularly to method of testing torsional vibration at different locations in vehicle driving condition.
BACKGROUND OF INVENTION
In current competitive and customer oriented auto industry; there is an increasing demand for passenger comfort and safety. Comfort can be directly attributed to the Noise, Vibration and Harshness characteristics of the vehicle. Mostly the noise and harshness are coupled with the vibrations being generated in the vehicle. Following are the two main sources of the vibration --Power train generated/excited. -Road generated/excited.
Power train mainly consists of Engine, Gearbox, Propeller shaft or Drive shafts, Drive axles and Wheel hubs. Any vibrations generated can be classified in following two main categories --Linear vibrations -Angular vibrations
Angular vibrations generated in the Powertrain as usually called as Torsional vibrations. Mainly the engine is the source of Torsional vibrations. Ignition and combustion within cylinders causes momentarily rise and fall in the combustion gas pressure and in turn variation in angular acceleration of the crankshaft which is termed as Torsional vibrations. These vibrations are further passed through the entire drive train to the body through vehicle suspension and mounts.
In conventional method of torsional vibration testing the torsional vibration is measured at aggregate level like on the engine at the engine test bed. This


provides only the local information about the torsional vibrations present at the engine output, with which it is not possible to correlate the driver perception. This method is inadequate to measure and map the over all vehicle level performance and to perform the root cause analysis.
OBJECTS OF INVENTION
The main object of this invention is to provide Method of testing in-vehicle condition power train torsional vibration for vehicle.
Another object of this invention is to provide a method of testing torsional vibration on vehicle in dynamic conditions which will be able to give more realistic testing conditions than the test rig.
Yet another object is to provide a method of testing torsional vibration at different locations simultaneously namely at engine output (1), gearbox output (2), rear axle input (3) and front wheel end (4).
Yet another object of this invention is to provide a method of testing of torsional vibration to investigate the effect of clutch, gearbox in torsional vibration propagation from engine to gearbox output and the effect of yoke types, propeller shaft characteristics and rear axle inclination angles in torsional vibration propagation from gearbox output to rear axle input.
Yet another object of this invention is to provide a method of testing of torsional vibration, which is simple and requires less effort and time.
STATEMENT OF INVENTION
Method of testing in-vehicle condition power train torsional vibration for vehicle comprises of


a. Identifying the vehicle on which testing is to be performed;
b. Mounting a sensor on a flywheel housing perpendicular to the flywheel
tangent;
c. Mounting toothed wheel on gear box output yoke and differential input yoke;
d. Mounting sensors on toothed wheel of step (c) perpendicular to the tangent of
said toothed wheel;
e. Instrumentation of the vehicle by connecting sensors provided on engine
output, gear box output and differential input separately to data acquisition
system for torsional vibration data collection;
f. Collecting torsional vibration data in throttle wide open and coasting test
condition in each gear by driving the vehicle on horizontal surface;
g. Analyzing the collected torsional vibration data for angular acceleration,
speed fluctuation and vibration angle for said test condition.
Method of testing in-vehicle condition power train torsional vibration for vehicle comprises of
a. Identifying the vehicle on which testing is to be performed;
b. Mounting a sensor on a flywheel housing perpendicular to the flywheel
tangent;
c. Mounting toothed wheel on gear box output shaft;
d. Mounting sensors on toothed wheel of step (c) perpendicular to the tangent of
said toothed wheel;
e. Mounting sensor on anti lock braking system toner wheel at both front wheel
end;
f. Instrumentation of the vehicle by connecting sensors provided on engine
output, gear box output and front wheel end separately to data acquisition system
for torsional vibration data collection;
g. Collecting torsional vibration data in throttle wide open and coasting test
condition in each gear by driving the vehicle on horizontal surface;
h. Analyzing the collected torsional vibration data for angular acceleration, speed fluctuation and vibration angle for said test condition.


BRIEF DESCRIPTION OF INVENTION
In Method of testing in-vehicle condition power train torsional vibration for vehicle, Torsional vibrations were measured and mapped along the complete Powertrain starting from engine to wheel end on the vehicle in different driving events. This enables to perform the root cause analysis and to identify the things gone wrong in the Powertrain/Driveline.
This involves following major steps -
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 angular velocity at following
locations -
Engine out (1) (Flywheel / Ring gear) - to capture the angular accelerations/
Torsional vibrations generated and passed on to the driveline.
Gearbox out (2) - to evaluate and map the progress/status of Torsional vibrations
at the gearbox out.
Differential input (3) - to capture the torsional vibration which ultimately passes
to passenger cabin through suspension, chassis and body.
Front wheel end (4) - to evaluate and map the progress/status of Torsional
vibrations at the front wheel end.
Data Acquisition - Instrumented vehicle is driven in each gear as per devised
test condition to collect the Torsional vibration data. The test condition are as
follows:
Wide open throttle in each gear
Coasting in each gear
Data Analysis - The collected data is post processed using software tools to
understand and quantify the Torsional vibrations along the Powertrain at various


measurement locations. Complete analysis enables to know the Torsional vibration flow across the driveline and helps to identify the area which needs the improvement.
BRIEF DESCRIPTION OF DRAWINGS
Figure 1 - shows typical instrumentation for Method of testing in vehicle
condition power train torsional vibrations for vehicle
Fig 2 (a) - shows fly wheel housing mounted with sensor.
Fig 2 (b) - shows gear box output yoke mounted with sensor.
Fig 2 (c) - shows differential input yoke mounted with sensor.
Fig 2 (d) - shows front wheel end mounted with sensor.
Figure 3 - shows analysis plot for 3D order analysis of angular acceleration
(rad/sec2) Vs engine RPM at engine output.
Figure 4 - shows 3D analysis plot for engine speed fluctuation Vs engine RPM
for two revolution of crankshaft.
Figure 5 - shows 2D analysis plot for speed fluctuation Vs time at engine output,
gearbox output and axle input.
Figure 6 - shows analysis plot for angular acceleration (rad/sec2) Vs engine RPM
for engine output, gearbox output and axle input.
Figure 7 - shows analysis plot for vibration angle (Degree) Vs engine RPM for
engine output, gearbox output and axle input.
Figure 8 - shows the process flow chart for Method of testing in vehicle
condition power train torsional vibrations for vehicle.
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 8,
The method of testing power train torsional vibration in-vehicle 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 torsional vibration testing the whole driveline is divided into two blocks. The first block is from engine to gearbox and second block from gearbox to rear axle.
Method of testing in-vehicle condition power train torsional vibration for vehicle consists of following steps -
a. Identifying the vehicle having rear wheel drive on which testing to be
performed;
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 speed
fluctuations;
c. Preparing gear box output yoke (6) with tooth wheel required for
scanning by sensor (7) for acquiring torsional vibration data and preparing
fixture (8) for mounting sensor (7) on gear box out put yoke mounted tooth
wheel vertically to sense the Gear box output speed fluctuations;
d. Preparing differential input yoke (9) with tooth wheel required for
scanning by sensor (10) for acquiring torsional vibration data and preparing


fixture (11) for mounting sensor (10) on differential input yoke (9) vertically to sense the rear propeller shaft speed fluctuations;
e. Assembling said gear box output yoke and said differential input yokes
on vehicle.
f. Preparation of fixture (14) for mounting sensor (13) to sense the anti lock
braking system toner wheel (front wheel end) speed fluctuations;
g. Instrumentation of the vehicle by assembling sensors on engine output,
gear box output and differential input with the help of said fixtures for torsional
vibration data collection.
h. Collecting torsional vibration data in throttle wide open and coasting test condition in each gear;
i. Analyzing the collected torsional vibration data for angular acceleration, speed fluctuation and vibration angle for said test condition.
For acquiring torsional vibration data at engine output a magneto resistive sensor is mounted on fly wheel and is directed to the centre line of 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. Sensor mounted on gear box, differential, anti lock braking system toner wheel is directed to the centre line of toothed wheel. Figure 1 shows the various measuring locations to capture the Torsional vibrations along with Powertrain.
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(a), 2(b), 2(c) and 2(d) shows mounting details of the sensors.
The data is collected in each gear at following test conditions -


Wide open throttle - Vehicle is driven from standstill to maximum speed with clutch engaged, full throttle and no braking.
Coast down - Vehicle is driven from maximum speed to standstill in clutch engaged condition, with no throttle and braking.
After successful data acquisition following analysis is performed -
a. 3D order analysis for peak angular acceleration Vs engine RPM for
engine out. This tells angular acceleration (torsional vibration) w.r.t orders and
engine RPM. Also we can quickly find the dominating orders. Which is shown
clearly in figure-3
b. 3D speed fluctuation analysis Vs engine RPM for two revolution of
crankshaft for engine out. This tells the speed fluctuation in one engine cycle.
Which is shown clearly in figure-4
c. 2D speed fluctuation analysis Vs time for all three location engine out,
gearbox out and axle input. This tells the minimum and maximum speed
fluctuations over entire duration of test. Which is shown clearly in figure-5
d. 2D angular acceleration analysis Vs engine RPM for all three location
engine out, gearbox out and axle input. This tells the torsional vibrations trend
over entire Engine speed for second order. Which is shown clearly in figure-6
e. 2D vibration angle analysis Vs engine RPM far all three location engine
out, gearbox out and axle input. This tells the angular displacement over entire
Engine speed for second order. This is shown clearly in figure7.
Analyzed data is then compared between various measurement locations to map the torsional vibrations at each location and its progress along the Powertrain. These results are then compared against target vehicles.
Analyzed data/result helps to identify the area which needs refinement to reduce the Torsional vibrations.
Method of testing in-vehicle condition power train torsional vibration 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 testing in vehicle condition power train torsional vibrations for vehicle, wherein said magneto resistive sensor are placed so that its axis is perpendicular to the tangent of tooth wheel.
Method of testing in vehicle condition power train torsional vibrations 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 testing in vehicle condition power train torsional vibrations for vehicle, wherein vehicle is tested at wide open throttle and coast down condition in each gear.
Fine tuning of the power train components may required with the aim to reduce torsional vibration by using results obtained by a method of testing power train torsional vibrations for rear wheel drive vehicle.
BENEFITS OF THE PROPOSED METHOD
1. As the current Torsional vibration mapping is done simultaneously at all the three location i.e. engine output (1), gearbox output (2) and axle input (3), there by we can analyze the flow of Torsional vibration from engine to gearbox and from gearbox to differential and thus the problematic area can be identified.
2. As the measurements are performed on the vehicle, which helps to capture the real performance of the vehicle.


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.


WE CLAIM

1. Method of testing in-vehicle condition power train torsional vibration for vehicle comprises of
a. Identifying the vehicle on which testing is to be performed;
b. Mounting a sensor on a flywheel housing perpendicular to the
flywheel tangent;
c. Mounting toothed wheel on gear box output yoke and differential
input yoke;
d. Mounting sensors on toothed wheel of step (c) perpendicular to the
tangent of said toothed wheel;
e. Instrumentation of the vehicle by connecting sensors provided on
engine output, gear box output and differential input separately to
data acquisition system for torsional vibration data collection;
f. Collecting torsional vibration data in throttle wide open and
coasting test condition in each gear by driving the vehicle on
horizontal surface;
g. Analyzing the collected torsional vibration data for angular
acceleration, speed fluctuation and vibration angle for said test
condition.

2. Method of testing in-vehicle condition power train torsional vibration
for vehicle comprises of
a. Identifying the vehicle on which testing is to be performed;
b. Mounting a sensor on a flywheel housing perpendicular to the
flywheel tangent;
c. Mounting toothed wheel on gear box output shaft;
d. Mounting sensors on toothed wheel of step (c) perpendicular to the
tangent of said toothed wheel;


e. Mounting sensor on anti lock braking system toner wheel at both
front wheel end;
f. Instrumentation of the vehicle by connecting sensors provided on
engine output, gear box output and front wheel end separately to
data acquisition system for torsional vibration data collection;
g. Collecting torsional vibration data in throttle wide open and
coasting test condition in each gear by driving the vehicle on
horizontal surface;
h. Analyzing the collected torsional vibration data for angular acceleration, speed fluctuation and vibration angle for said test condition.
3. Method of testing in-vehicle condition power train torsional vibration for vehicle as claimed in claims 1 or 2 wherein said sensor is provided on a fly wheel by drilling a tapped hole on flywheel housing and using fixture to sense the Engine output speed fluctuations.
4. Method of testing in-vehicle condition power train torsional vibration for vehicle as claimed in claims 1 to 3 wherein said sensor is provided on a said gear box by using fixture attached to gear box casing to sense the Gear box output speed fluctuations.
5. Method of testing in-vehicle condition power train torsional vibration for vehicle as claimed in claims 1 to 4 wherein said sensor is provided on a said differential or front wheel end by using fixture to sense the rear propeller shaft or front wheel end speed fluctuations.
6. Method of testing in-vehicle condition power train torsional vibration for vehicle as claimed in claims 1 to 5 wherein said sensor provided on fly wheel is directed to the centre line of ring gear.


7. Method of testing in-vehicle condition power train torsional vibration for vehicle as claimed in claims 1 to 5 wherein said sensor provided on gear box and differential or anti lock braking system toner wheel is directed to the centre line of toothed wheel.
8. Method of testing in-vehicle condition power train torsional vibration for vehicle as claimed in claims 1 to 7 wherein said instrumentation of vehicle comprises transistor transistor logic (TTL) converter provided between out put of said sensors and input of data acquisition system.
9. Method of testing in-vehicle condition power train torsional vibration for vehicle as claimed in claims 1 to 8 wherein said sensors used are of magneto resistive type.
10. Method of testing in-vehicle condition power train torsional vibration for vehicle substantially as herein described with reference to accompanying drawings.


ABSTRACT
Method Of Testing In-Vehicle Condition Power Train Torsional Vibration For Vehicle
Method of testing in-vehicle condition power train torsional vibration for vehicle comprises of following steps - (a) identifying the vehicle on which testing is to be performed; (b) mounting a sensor on a flywheel housing perpendicular to the flywheel tangent; (c) mounting toothed wheel on gear box output yoke and differential input yoke; (d) mounting sensors on toothed wheel of step (c) perpendicular to the tangent of said toothed wheel; (e) instrumentation of the vehicle by connecting sensors provided on engine output, gear box output and differential input separately to data acquisition system for torsional vibration data collection; (f) collecting torsional vibration data in throttle wide open and coasting test condition in each gear by driving the vehicle on horizontal surface; (g) analyzing the collected torsional vibration data for angular acceleration, speed fluctuation and vibration angle for said test condition.
Fig. 1