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 Durability Testing Device For Automotive Components And A Method Of Testing Automotive Components Therewith


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. S B Menon, Mr. B S Venkatesha Murthy,
Mr. Milind A Bankar, Mr. Hari Srinivas Babu Aggarapu
and Mr. Swapnil R Salunkhe
All are 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 to a durability testing device for automotive components and method of testing of automotive components therewith. This invention particularly applicable in testing the durability of components against mud and slurry.
BACKGROUND OF INVENTION
Automotive vehicles during its service life have to work in various environmental extremities. During rainy season, operating in mud and slurry conditions is one among them. Testing of components for such conditions required complex test equipments with efficient control system. Based on the durability requirements of a particular component; many accelerated test procedures are available to estimate the suitability of particular design. To predict real life usage and to evaluate components various testing methods and apparatus capable of testing under real life usage are available. For many rotating parts, the life of the component is dependent on the effectiveness of the seal used in the design. Many testing procedures are available to check the suitability of the seal design for various loading conditions. However, for components like wheel hub bearing, power steering pumps etc, more sophisticated test systems with capacity to control the test environment and loads are the need of the hour. Prior art search reveals US Patent Nos. 4,798,086, 3,942,375, 5,000,664 and CIPO Patent No. 2,098,677 wherein, various methods and apparatus of testing are published. However, all the above patents teach apparatus that are capable of measuring either performance or limited durability methods. This is because these components were not subjected to real life conditions, either due to in-vehicle location or environmental conditions in which it operates or both. Moreover, automotive components that are under continuous rotation and are exposed to adverse environmental conditions, like power steering pump, hub bearings etc, are required to be robust. In order to simulate these environmental conditions and subject the parts like hub bearing and power
2

steering pumps, a new durability testing apparatus and method of testing thereof is devised.
OBJECTS OF INVENTION
1) The main object of this invention is to provide a testing apparatus for durability testing of rotating automotive underbody components under mud and slurry conditions with load.
2) The main object of this invention is to provide a testing apparatus for durability testing of wheel hub bearing under mud and slurry conditions with load.
3) Another object of this invention is to provide a testing apparatus for durability testing of Power steering pump under mud and slurry conditions with load.
4) Yet another object of this invention is to provide a test apparatus that is easy to install, commission with minimal manufacturing and maintenance cost and to provide a methodology for validating wheel hub bearing and power steering pump simulating actual customer usage conditions.
STATEMENT OF INVENTION
This invention relates to a durability testing device for automotive components under mud and slurry conditions which comprises a drivable test rig provided with means for holding an automotive component, a slurry tank containing mud and slurry provided with a stirrer, means for pumping and spraying the mud and slurry on to the mounted automotive component, means for applying axial and radial load on said component if desired and a programmed controller to regulate the test cycle.
3

This invention also includes a method of testing the durability of automotive components such as under body components, wheel hub power steering pump under mud and slurry conditions comprising the steps of mounting the automotive component on a drivable rig member; spraying homogenized mud and slurry thereon at predetermined cycles while applying radial and axial load on components like automotive steering pump, if necessary under predetermined cycles for a predetermined period and thereafter assessing the percentage of water ingress within the tested automotive component.
SUMMARY OF INVENTION
This invention is related to the test apparatus and test methodology which is used to evaluate the performance and reliability of rotating automotive underbody components such as wheel hub bearing or power steering pump. These components are rotated under load and mud and slurry is sprayed on it under required pressure and flow.
Generally in all the passenger and commercial automotive vehicles under body parts are exposed to mud and slurry environment. This ingress of mud and slurry into these components will deteriorate the performance of that particular component resulting in reduced life.
This invention covers the details of building a test apparatus used for validating under body rotating vehicle components when they are exposed to mud and slurry conditions. It also encompasses the test procedure, test cycle and test specifications for validating such components. It mainly covers the testing of wheel hub bearing assembly and power steering pump.
This equipment is used for the evaluation of hub bearing or power steering pumps. It validates the capability of these components to perform for prescribed life in mud and
4

slurry conditions. It simulates a field like condition in which the components are subjected to load and adverse environmental conditions.
This rig has been developed to simulate the actual road like, load conditions with the help of axial and radial hydraulic actuators. Test rig is compact in construction, easy to operate and cost effective.
This test rig is an effective tool used for early design feedback of a new design of wheel hub bearing and power steering pumps.
BRIEF DESCRIPTION OF DRAWINGS
Fig. 1 Schematic sketch shows the mud and slurry test
Fig. 2 Schematic sketch shows the mud and slurry test with load for testing wheel hub
assembly.
Fig. 3 Schematic sketch shows the mud and slurry test with load for testing power
steering pump.
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.
This invention is more related to simulate the ingress of mud and slurry into the automotive components which are subjected to such kind of environment in the actual usages. For example, in a vehicle many under body parts are subjected to constant exposure of mud and slurry. As a case in this invention wheel hub bearing assembly and power steering pump test methodology are being explained elaborately along with the test specifications. Test component is subjected to radial and cornering loads
5

transferred through wheels. In addition to that in the rainy season when the vehicle travels through the muddy roads, mud and slurry is splashed by the wheel rearwards and also some content of that mixture gets splashed over the under body parts such as wheel hub bearing assembly, power steering pump etc. Under this situation there is a possibility of this mud and slurry ingress in to the under body rotating components which further will deteriorate the performance and their life further.
In fig. 1 the rotating automotive underbody component (1) is mounted on the test rig with suitable holding fixture. The test assembly is rotated by means of a motor (2) through a flexible coupling with specified speed.
Mud and slurry application mechanism consists of a mud and slurry tank (6) in which slurry mixture (7) is maintained up to certain level. This mixture is agitated by a mechanical stirrer (8) to maintain the homogeneity of the mixture. Further this slurry is pumped up to the nozzle jet (9) by means of a slurry pump (10) through a special ball and socket type flexible plastic hose (11). Nozzle is positioned inclined to the test component. It is capable of delivering the test medium at the rate of 1 litre per minute at 4 to 8 bar.
After assembling the test part on to the test rig with suitable adaptors, rotate the test assembly at a specified speed. Once it is stabilized impinge the slurry as per the specifications on the part under test. Controller (12) is used for programming the test cycle and performing the actual test on the apparatus.
Testing Wheel Hub Bearing Assembly
Referring to figure 2, the wheel hub bearing assembly (1') is mounted on the test rig with suitable holding fixture. Conventional holding means such as couplers, adaptors and spindles hold the test specimen in the rig. The test assembly is rotated by means of a motor (2) through a flexible coupling with specified speed.
6

Axial and Radial loads are applied through hydraulic cylinders (3) and (4) respectively. These loads create a variable bending moment on the test part. This loads are applied at the wheel contact patch. These double acting cylinders are powered by a hydraulic power pack (5) of a suitable capacity.
Mud and slurry application mechanism is prepared as described above. It is capable of delivering the test medium at the rate of 1 litre per minute at 6 to 8 bar.
After assembling the test part on to the test rig with suitable adaptors, rotate the test assembly at a specified speed. Now apply the radial and cornering load to the test component through the test fixture. Once it is stabilized impinge the slurry as per the specifications on the part under test. Controller (12) is used for programming the test cycle and performing the actual test on the apparatus.
Test Medium:
The test medium shall consist of a mixture of water, test powder as per JIS Z8901, class-8 and salt in the proportions 10:4:1 (by weight), respectively.
Test Method and Cycle:
a) Rotate the hub bearing assembly at 1000 rpm for 45 minutes ON and 10 minutes OFF again 5 minutes ON.
b) Simultaneously the nozzle shall spay the slurry for 10 minutes ON and 10 Minutes OFF alternately.
c) Apply the cornering loads (± 0.3g) for 50 minutes ON and 5 minutes OFF and again 5 minutes ON
d) This completes 1 test cycle, repeat this for 100 cycles which is equivalent to 100 hours of test duration on the test rig.
7

Acceptance Criteria:
Percentage content of water in bearing grease should not exceed 1.5% by weight. Bearing should be free from any spalling , physical damage and any abnormal noise. Similarly, for a power steering pump, same test set-up as explained in Fig 2 above shall be used along with the following test specifications:
Testing Power Steering Pump For Mud And Slurry:
Referring to figure 3 the test pump (1") is connected to the electric motor (2) thru a suitable drive unit. The entire electric motor along with pump fixture is placed on a suitable platform below which is placed a tank for power steering oil (13). Along side the power steering oil tank, another tank (7) is placed which consist of water mixed with mud in a suitable proportion i.e 50 gms of testing dust Type-8 as per JIS-Z 8901 for every 1 liter of water to make mud & slurry mixture. For achieving a homogeneous mixture of the mud and slurry, an electric motor with a stirrer (8) is placed in the tank which rotates continuously. Above this mud and slurry tank, another electric motor (10) coupled with suitable drive to pump mud and slurry thru 2 nozzles provided near the test pump as shown. The 2 nozzles are so placed near the pump so as to spray the mud and slurry similar to the vehicle exposed conditions.
Test Method & Cycle:
a) Rotate the motor coupled with pump at 7000 - 8000 RPM.
b) Simultaneously ,the nozzle shall spray the slurry at a pressure of 4 ~5 bar at the specified locations as shown in the fig:
c) Power steering oil temperature shall be maintained at 55 °c ~ 60 °c (min).
d) With the pump running at the above RPM, slurry shall be sprayed on pump for 16 hours followed by 4 hours without spray but with pump in running condition.
8

e) Subsequently, pump shall be kept idle i.e. without running and no slurry spray for another 4 hours.
f) The above sequence test procedure explained in iv & v above with pump running and slurry spray and then pump idle and without slurry spray constitutes 1 cycle (i.e 24 hrs in total).
Acceptance Criteria:
After completion of '85 cycles:
i) Percentage content of water in Power steering oil shall not be exceeding 5%
by volume.
ii) Power steering pump internals shall be free from any water/mud entry.
iii) No physical damages /Jamming of pump bearing/bush shall be allowed.
iv) No abnormal noise shall be allowed.
9

WE CLAIM
1. A durability testing device for automotive components under mud and slurry
conditions comprising :
a drivable test rig provided with means for holding an automotive component, a slurry tank containing mud and slurry provided with means for pumping and spraying the mud and slurry on to the mounted automotive component, means for applying axial and radial load on said component if desired and a programmed controller to regulate the test cycle.
2. The device as claimed in claim 1, wherein a motor is provided for rotatably driving the automotive components mounted on the rig of the device.
3. The device as claimed in claims 1 and 2, wherein said means for pumping and spraying is a compression pump provided with atleast one jet spray means which is inclined to direct the spray to the mounted automotive component.

4. The device as claimed in claims 1 to 3, wherein said means for applying axial and radial loads are hydraulic cylinders.
5. The device as claimed in claim 1 wherein said slurry tank provided with a mechanical stirrer.
6. A method of testing the durability of automotive components such as under
body components, wheel hub power steering pump under mud and slurry conditions
with a device as claimed in claims 1 to 5, comprising the steps of:
mounting the automotive component on a drivable rig member; spraying homogenized mud and slurry thereon at predetermined cycles while applying radial and axial load on components like automotive steering pump, if
10

necessary under predetermined cycles for a predetermined period and thereafter assessing the percentage of water ingress within the tested automotive component.
11
7. A durability testing device for automotive components under mud and slurry conditions substantially as herein described with particular reference to the figures in the accompanying drawings.
8. A method of testing the durability of automotive components substantially as herein described with particular reference to the figures in the accompanying drawings.