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


TITLE OF THE INVENTION Test set up & test Methodology for testing Engine Cradle
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.A.M.Kajalkar and Mr.G.A.Pingle
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 description particularly describes the invention and the manner in
which it is to performed.


FIELD OF INVENTION
The present invention relates to the method of engine cradle testing on automobile vehicle by taking into consideration critical loads like longitudinal load, lateral load and the phase in which it is operated, with the actuators to reduce the testing time.
BACKGROUND OF INVENTION
The main function of engine cradle to provide structural support to the engine.
A cradle or a sub frame (4) is a chassis structural component that is utilizes to support
engine power train in front wheel drive and rear wheel drive vehicles.
A engine cradle (4) structure having a longitudinal members and cross members which is attached to a body of vehicle (13).
An engine cradle is removable fame component that helps to hold engine in place and can be removed to facilitate installation / removal of engine from the vehicle. Traditionally engine cradle manufactured by using stamped steel, weldmets. Recently automobile designers are considering alternative processes, i.e.hydroforming, and also light weight materials used for engine cradle.
A vehicle level test was carried out for newly developed engine cradle. During vehicle level test, failure was observed on engine cradle. To take care of failures design modification had been done on engine cradle. Validation of modification was required for durability worthiness of a cradle. An aggregate level test was done on the rig to reproduce the failure on existing design which was failed in vehicle testing.
After failure simulation on the rig, modified cradle was tested to check the comparative durability life.


In conventional method of testing, vehicle is updated with component to be tested
(cradle).Vehicle is tested on specially designed torture tracks or highway to cover
required target life cycles/kilometers.
To test any component/system on vehicle level 3 to 4 months are required.
In vehicle development program 3 to 4 month is long period, hence aggregate level
accelerated testing is preferred. Aggregate level testing gives result in very short time
(with in 10 days). In aggregate level testing component were tested with one axis load
at a time. In conventional method of component testing, component is tested in only
one direction load at a time and it takes more time for testing. In conventional testing
actual vehicle condition can not be reproduced as on vehicle at a time 'X', 'Y' or 'X',
'Y', 'Z' direction loads are subjected at same instance.
To reduce time of testing new procedure and technique is used.
OBJECTS OF INVENTION
The main objectives of the present inventions to reduce testing time. Testmg time is saved by using two actuators in loop and out of loop as an accelerated way of testing but achieving the objectives.
SUMMARY OF INVENTION
This invention is more related to the reduction in testing time. Testing time is saved
by using two actuators in loop as an accelerated way of testing, but achieving the
objective.
Test setup is also made in a way to reproduce vehicle condition in lab testing.
The test rig consists of:
• Servo hydraulic actuator in 'X' direction
• Servo hydraulic actuator in 'Y' direction

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• Load cells in 'X' and 'Y' direction attached to the servo-hydraulic actuator for
sensing the load.
The details of the above are mentioned in the detailed description of the test rig.
Measurement system
• Customized software used for operating the test rig.
• Data acquisition system was used for acquiring & processing the measured data.
• Servo hydraulic actuators and load cells were used for sensing the load.
STATEMENT OF INVENTION
Accordingly the present invention discloses a test setup for testing engine cradle comprising at least two actuators adapted for loading wheel reactive point simultaneously with critical longitudinal and lateral loads in the operating phase of the load; plurality of blocks clamped on floor configured to mount vehicle by coupling vehicle wheel hubs on said blocks; at least two load cells adapted for sensing load are connected to said actuators; at least two rod end bearing configured to refrain side load and cross talk on said actuators; at least two roller assemblies one on another separated by a plate provided at wheel hub point for connection of actuators to refrain mass transfer of said actuators on test sample and to allow free displacement of the wheel hub loading point in x and y direction and to constrain the wheel hub loading point in negative z direction.
This invention also includes a method for testing engine cradle under critical load conditions as described above, which comprises the steps of; removing wheels from vehicles for mounting vehicle on the blocks through wheel hub; front left, right and rear right wheel hubs are clamped to the said blocks; clamping the blocks on floor to

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obtain rigidity; connecting actuators to load cells for sensing the load; providing a fixture between load cell and actuator piston rod facilitated for sliding over the roller assembly; providing a rod end bearing after said load cells; connecting longitudinal and lateral actuator piston rods to wheel hub through rod end bearing and front portion of actuator supported on roller arrangement; connecting rear ends of the actuators to the ball joint and mounting it on vertical columns; starting test for specified loads by keeping the longitudinal and lateral actuators in loop.
BREIF DESCRIPTION OF DRAWINGS
According to the present invention,
Figure. 1 shows the layout of testing the engine cradle by using two actuators in X and
Y direction.
Figure.2 shows detail arrangement of actuator connection with rod end bearing and
roller arrangement.
Figure 3 shows schematic layout of engine cradle longitudinal and lateral loading test.
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.
A set up using two servo hydraulic actuators was designed such that one actuator will
give load in 'X' direction (2) and one will give load in Y direction (1).
Test was carried out by making two actuators together with rod end bearing which
avoids side loads coming on the actuators and avoid cross talks.
Also roller arrangement is provided on the bottom of front portion of actuators to
avoid longitudinal and lateral mass transfer of actuator.
This arrangement will give 'Xs and 'Y' load in loop as per observed on vehicle, but
eliminating the cross coupling of 4X'-'Y' forces.

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TEST SET UP: -
In test set up vehicle is mounted on the blocks through wheel hub. Front wheels (11)
and Rear right wheel (12) is restricted through wheel hub by coupling it to blocks.
The test setup is such that longitudinal and lateral wheel load inputs can be given
simultaneously in phase or out of phase through one of the wheel reactive points
through X and Y direction actuators (2) and (1)
Load cells are connected to the 'X' (9) and 'Y' (10) direction actuators to sense the
load.
The load gets transferred to B1W (13) and finally gets reacted at the wheel centre
points.
The remaining 3 wheel center points are appropriately constrain in 'X', 'Y', &
'Z'direction to react the loads (11) & (12).
The loading arrangement is such that two actuators connected together with rod ends
which avoids cross load coming on the actuators. Also rollers were provided on front
portion of actuator to avoid the actuator own mass transfer on vehicle also the
longitudinal and lateral loads are applied simultaneously but does not interact with
each other (6).
Rollers were provided on front portion of actuator to avoid longitudinal & lateral
weigh and does not load test item /shell (7).
Conversely the test item /shell weight is supported independently.
TEST METHODOLOGY: -
Test Methodology was derived based on: a) Analysis of field failure :
Field failure was observed on the Accelerated vehicle durability test. Failure mode was studied and critical loads for failure was analyzed. Strain gauging was done on the failure locations of engine cradle

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Sensitivity analysis done to get the idea of critical directions of loads causing the failure. Based on this exercise critical load causing the failure was analyzed.
b) Critical loads causing the failure:
Road load data time history of torture track was refereed to get the idea of load, the assembly is subjected in the field.
c) Analysis of Wheel Force Transducer data captured on vehicle in field: Wheel force transducer data captured on Torture track and was referred to find out damaging critical loads for failure.
d) Based on above analysis following test specifications were derived: Longitudinal load - 1 X (RAW/2)
Lateral load - 0.3 X (RAW/2)
Phase - Out of phase
No. of cycles
Target life - 16,00,00 Kms
e) Proving of test methodology:
1) Test was conducted with this specification on sample of existing design and field failure was simulated and correlated.
2) Modified design was tested with same specification and met the target life Similar modified design samples were fitted on vehicle and no failures was reported till vehicle completed its target life in field.
This is how the test methodology was verified.
TEST STEPS INVOLVED:-
1) Vehicle wheels removed and Vehicle mounted on the blocks through wheel hub.
2) Front LH, RH and Rear RH wheel clamped to the blocks.
3) Blocks clamped on the floor.
4) Actuators were connected to load cells.


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5) A fixture is provided between load cell and actuator piston rod which will side on roller.
6) After load cell rod end bearing provided to the actuator.

7) Longitudinal and lateral actuator piston rods are connected to the wheel hub through rod end bearing and front potion of actuator was supported on roller arrangement.
8) Rear end of the actuators connected to the ball joint and mounted on the vertical columns.
9) Actuator Load cell and LVDT was connected to controller for sensing the load.
10) Test to start for specified loads by keeping the Longitudinal and Lateral actuators
in the loop.
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.

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WE CLAIM
1. A test setup for testing engine cradle comprising
at least two actuators adapted for loading wheel reactive point simultaneously with critical longitudinal and lateral loads in the operating phase of the load;
plurality of blocks clamped on floor configured to mount vehicle by coupling vehicle wheel hubs on said blocks;
at least two load cells adapted for sensing load are connected to said actuators;
at least two rod end bearing configured to refrain side load and cross talk of said actuators;
at least two roller assemblies provided at wheel hub loading point for connection of said actuators adapted to refrain mass transfer of said actuators on test sample and to allow free movement of wheel hub loading point in x and y direction and to constrain the wheel hub loading point in negative z direction.
2. The test setup as claimed in claim 1, wherein the front left hand, right hand and rear right hand wheel hubs mounted on said blocks are coupled to said blocks for clamping purpose and the rear left wheel hub is configured for load testing at its said reactive point by the said actuators.
3. The test setup as claimed in claim 1, wherein said actuators are the servo hydraulic actuators.
4. The test setup as claimed in claim 1, wherein said test set up is configured for loading in phase as well as out of phase.
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5. The test setup as claimed in claim 1, wherein said critical loads applied at rear left wheel hub point gets transferred to the body in white (body of the vehicle) and finally reacts at the remaining wheel centre points.
6. The test setup as claimed in claim 1, wherein loadcell is used with said actuator for sensing the load.
7. The test setup as claimed in claim 1, wherein a fixture is provided between the actuator piston rod and said load cell configured to slide on said roller assembly.
8. A method for testing engine cradle under critical load conditions as described above, which comprises the steps of;
removing wheels from vehicles for mounting vehicle on the blocks through wheel hub;
front left, right and rear right wheel hubs are clamped to the said blocks;
clamping the blocks on floor to obtain rigidity;
connecting actuators to load cells for sensing the load;
providing a fixture between load cell and actuator piston rod facilitated for sliding over the roller assembly;
providing a rod end bearing after said load cells;
connecting longitudinal and lateral actuator piston rods to wheel hub through rod end bearing and front portion of actuator supported on roller arrangement;
connecting rear ends of the actuators to the ball joint and mounting it on vertical columns;
starting test for specified loads by keeping the longitudinal and lateral actuators in loop.

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9. A test setup for testing engine cradle substantially as hereinabove described with reference to the accompanying drawings.
10. A method for testing engine cradle under critical load conditions substantially as herein above described.

Dated this 30th day of March 2009

TATA MOTORS LIMITED By their Agent & Attorney

Karuna Goleria of DePENNING & DePENNING
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