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


TITLE OF THE INVNTION
A DEVICE FOR EVALUATING HUB BEARING SEALS
AGAINST INGRESS OF DUST AND A METHOD FOR
EVALUATING HUB-BEARING SEALS
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. B S Venkatesha Murthy, Mr. A Chandrashekhar,
Mr. Milind A Bankar, Mr. S B Menon all 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 device for evaluating hub-bearing seals against ingress of dust and a method for evaluating hub-bearing seals. This device simulates extreme environmental conditions to which wheel hub bearing assembly is subjected to during its service life operations.
BACKGROUND OF INVENTION
Automobile bearings undergo different environmental conditions during their service life. For instance, in places like Rajasthan, automobiles function under extreme weather conditions on dusty and dry roads and under maximum load bearing capacity. Design of the wheel hubs bearing seals play an important role in safeguarding the bearings against the ingress of dust and sand. Under these conditions, ingress of dust and sand inside the bearing through these seals may occur resulting in premature damage of and failure of the bearings. Accordingly, it is essential to evaluate the evaluate dust ingress potential of bearing seals under simulated environmental conditions. Damaged bearing produces noise which is an irritant to the driver of the vehicle. Further, damaged bearing leads to increased functional drag which in turn reduces fuel economy.
OBJECTS OF THE INVENTION
The principal object of this invention is to provide a device for testing or evaluating the validation of wheel hub bearing seals against dry dust ingress.
Further, object of this invention is to provide a method of testing the validity of hub seals against dry dust ingress using the device.
Yet another object of this invention is to provide a simple, cost effective, easy to operate device capable of simulating field like environmental conditions.
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STATEMENT OF INVENTION
This invention relates to a device for evaluating performance and life of bearing seals under simulated conditions of load and environmental dry dust comprising a frame member provided with a drivable test regarding having axial and vertical actuators capable of aligning with a test fixture mounted with a test chamber which houses the bearing seal assembly for testing, means for rotating said assembly under load conditions exerted by the actuators and means for spraying dust said assembly to evaluate dust ingress under predetermined conditions.
This invention also includes a method of evaluating the performance and life of bearing seals under simulated conditions of load and environmental dust with a device as described above, which comprises the steps of mounting a bearing seal assembly in the dust chamber, aligning the same with the axial and vertical actuators, applying predetermined load thereon, while rotating said test assembly at a predetermined speed and exposing the same to a pressurized air stream containing dry dust for a predetermined period to evaluate and assess dry dust ingress through the seals to the bearing thereby assembling evaluating the life and validation of bearing seals.
SUMMARY OF INVENTION
The present invention is a device, which can carry out accelerated testing on a hub bearing seal under field like simulated conditions.
The test dust is stored in a dust chamber which is mounted around a test hub bearing assembly. This test is then sprayed onto the bearing seal area with the help of pressurized air. The test assembly is rotated at specified speed under load so that the deflection in the
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test part leads to the distortion of the seal which in turn will allow the entry of dust into the bearing. The whole purpose of inventing this test rig and developing the test methodology is to simulate the field like failure modes, in shorter time span and evaluate the bearing seal.
The bearing under test is mounted on the rig spindle with an adaptor. The hub bearing assembly is rotated by means of a motor. Further it is subjected to radial and axial loads simultaneously with predetermined magnitudes. This load represents the service load conditions, which hub bearing assemblies under in normal operations. Once the load and rotation are stabilized, the hub assembly is exposed to the test dust with a specific test cycle. The test set up, test methodology and test dust specifications are described completely in the detailed description of the invention.
BRIEF DESCRIPTION OF DRAWINGS
Fig. 1 shows the layout of hub bearing test rig with the arrangement of dust chamber and dust spray arrangement.
Fig 2 shows the test cycle details.
DETAILED DESCRIPTION OF INVENTION
Referring to the drawings wherein the showings are for the purpose of illustrating a preferred embodiment on the invention only, and not for the purpose of limiting the same.
Description about the test set up and equipment
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The invention is more related to the validation of bearing seal used in the wheel end bearing. The seal is used in the bearing to avoid the ingress of the dust particles into the bearing. Bearing is used in the wheel to minimize the rotary friction and take the forces to which the wheels are subjected due to vehicle weight and also due to the uneven road surfaces.
The test set up and test procedure is specifically developed for evaluating the performance and life of the bearing seals when they are exposed to the environmental factors specifically like dust.
The test rig comprises of an axial actuator (1) which is used for applying lateral load at dynamic tyre radius. Vertical actuator (2) is used for applying radial load onto the bearing. One end of the axial actuator is mounted onto the frame (3) and the other end to test fixture. In case of the vertical actuator top end is supported by the rig structure (4) whereas the bottom end is bolted to the test fixture (5) radial load is applied at the wheel centerline. The test assembly (6) is mounted on the plummer block (7) through an intermediate adaptor. The plummer block supports the motor (8) through a coupling.
Dust spray system consists of a dry dust chamber (9) a box fabricated out of sheet metal which is mounted round the test assembly. It is supported on a vertical stand (10). This box is made leak proof such that when the test dust (13) is sprayed on the hub bearing seal assembly by means of pressurized air from a compressor (12), through an air jet (11) dust spreads over the test parts and remains within the box and settles down in the reservoir at the bottom when the test is halted.
The test assembly which is mounted on the test rig is now rotated by the motor to the desired speed. Loads are applied to the hub bearing seal assembly through hydraulic actuators which are powered by a hydraulic power pack.
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Specific test cycle is programmed before the start of test for test duration, rpm, dust application rate, load cycle, temperature of the hub assembly through the controller.
Further specifications and practical details are given hereunder:
1. Bearing seal size range (which can be validated on this rig) - ID 30 to 60 mm, OD 50 to 100 mm, width 20 mm.
2. Test load range - Axial - 20kN / radial / 40kN max achieved by 50 LPM capacity hydraulic power pack.
3. Test speed - 200 to 1500 RPM achieved by 25 kw motor.
Other utilities used in the rig:
1. Electrical power 3 phase with neutral and earth.
2. Compressed air 2-5 bar to spray the dust on to the test hub bearing seal.
3. Test fixture for mounting hub bearing assembly. Will vary from vehicle model to model.
4. Special tools required mounting and dismounting of bearings to be tested.
5. Tools required for inspection of bearing seals after the test.
6. Lifting, shifting arrangement near the test rig for mounting and dismounting the test
assembly on to and from the rig.
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Test methodology and test cycle:
Test Method.
The test shall comprise a total of 5 cycle.
The cycle shall consist of a mixture of the following Phases:
a. The motor rotating the wheel bearing at 1500 rpm.
b. The air nozzle "ON", directing the jet towards test medium so
that it is sprayed on the complete wheel bearing assembly.
c. Apply dust to, seal rotating at 1500 rpm for 20 hours.
d. Stop rig and dust for 4 hours duration.
e. Repeat steps "a" through "d".
Acceptance Criteria of the test:
Bearing should be free from dust ingress through seal. Bearing should be free from any spalling and physical damage after opening the complete bearing.
The appended claims are not intended to limit the invention. Various modifications and alterations known to persons skilled in the art are within the scope and ambit of this invention.
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WE CLAIM
1. A device for evaluating the life and performance of bearing seals under simulated
conditions of load and environmental dry dust comprising a axial and vertical actuators
supported on a frame member; said axial and vertical actuators connected to a test fixture
mounted in a dust chamber which houses the bearing seal assembly for testing, means for
rotating said assembly under load conditions exerted by the actuators and means for
spraying dust to evaluate dust ingress under predetermined conditions.
2. The device as claimed in claim 1, wherein a spindle is provided on said rig wherein
said bearing seal assembly is mounted.
3. The device as claimed in claim 1, wherein said rotating means is a motor which rotatably drives said bearing seal assembly through an intermediate adaptor.
4. The device as claimed in claim 1, wherein said means for spraying dust comprises a compressor connected to an air jet.

5. The device as claimed in claim 1, wherein said axial and vertical actuators are hydraulically drivable.
6. A method of evaluating the performance and life of bearing seals under simulated conditions of load and environmental dust with a device as described above, which comprises the steps of mounting a bearing seal assembly in the dust chamber on a test fixture, connecting said test fixture with the axial and vertical actuators, applying predetermined load thereon, rotating said test assembly at a predetermined speed, and exposing the said dust chamber to a pressurized air stream for a predetermined period to
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evaluate and assess dry dust ingress through the seals of the bearing assembly thereby evaluating the life and validation of bearing seals.
7. The method as claimed in claim 6, wherein the steps are repeated 5 times, each cycle
having duration of four hours.
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8. A device for evaluating the life and performance of bearing seals substantially as herein described with particular reference to Figure 1 of the accompanying drawing.
9. A method for evaluating the life and performance of bearing seals substantially as herein described.