FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
[See section 10, rule 13]
TITLE OF THE INVENTION "DISC BRAKE SYSTEM"
APPLICANT
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. Sushil R Yadav, Mr. Datta S Kad, Mr. Somanathan M, Mr. Pramod P kulkarni
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 DESCRIPTON
The following specification particularly describes the disclosure and the manner in which
it is to be performed.

TECHNICAL FIELD
This invention relates to the brake system of an automobile and more particularly it relates to disc brake system.
BACKGROUND OF THE DISCLOSURE
Disc brake systems are commonly used brakes in automobiles due to their various advantages over traditional drum brake system, such as better cooling characteristics and lesser output sensitivity to temperature. During braking of the automobile the weight transfers from the rear to the front of the automobile, as a result more working load is induced on the front brakes. To support this requirement, the brake force distribution of typical automobile is designed to have 80:20 ratio, i.e. 80% of brake output will be provided by the front and the remaining 20% by the rear brake distribution.
Also, during braking, the kinetic energy of the automobile gets converted into heat energy. Since, more work is done by the front brakes, more heat will get generated. The brake output depends on brake friction material co-efficient, which in turn gets affected by the temperature. Therefore it is desired that the heat generated during braking is dissipated as fast as possible. The disc brake system provides better cooling as compared to the drum brake system. Generally, the disc brake systems are used as the front brakes and the drum brakes as the rear brakes. In high speed vehicles especially such as cars and vans, the disc brakes are used in both the front and the rear wheel ends. The disc brake system uses either solid disc or ventilated discs. Most commonly, the ventilated discs are used, due to their effective cooling characteristics.
However, due to increasing speed capabilities of modern vehicles, the brake systems need to kill more energy, which in turn produces more heat. To increase thermal absorption and thermal conductivity of the brake discs, design

improvement such as thickness, surface area improvement, material changes, such as ceramic discs, metal matrix composites are being developed. These material changes incur more cost. It is desirable to improve the thermal effectiveness of existing discs with design changes.
OBJECTS OF THE DISCLOSURE
The objective of disclosure is to provide a reliable, cost effective, easy to
manufacture, and simple brake disc system.
Another objective of the present disclosure is to provide a disc brake system that
has improved characteristics.
Another objective of the disclosure is to reduce the operating temperature of disc
brake system for the given application.
Further objects and features of the disclosure will become apparent from the
following detailed description when considered in conjunction with the drawings.
SUMMARY OF THE DISCLOSURE
The embodiments of the present disclosure relate to a disc brake system for an automobile. The disc brake system comprises; a brake disc adapted to be mounted on a wheel hub along a rotating axis thereof; at least one internal pocket formed within the brake disc, the at least one internal pocket capable of being filled with a heat transfer fluid; a plurality of heat exchanger fins extending outwardly from the internal pocket and thermally coupled with the heat transfer fluid filled in the internal pocket; and, a caliper assembly carried by the wheel hub and capable of engaging with the brake disc to resist rotational movement thereof.

BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 illustrates a partially cut side view of a disc brake system, in accordance
with an embodiment of the present disclosure,
FIG. 2 illustrates a perspective view of the disc brake system, in accordance with
an embodiment of the present disclosure, and
FIG. 3 illustrates a view of the test results obtained from the disc brake system, in
accordance with an embodiment of the present disclosure.
DETAILED DESCRIPTION OF THE DISCLOSURE
Referring now to the drawings wherein the showings are for the purpose of illustrating a preferred embodiment of the disclosure only, and not for the purpose of limiting the same.
FIG. 1 and FIG. 2 illustrate a partially cut side view of a disc brake system 100 and a perspective view of the disc brake system 100 respectively, in accordance with an embodiment of the present disclosure. The disc brake system 100 includes a brake disc 10. The brake disc 10 is adapted to be mounted on a wheel hub 12 of an automobile (not illustrated), along a rotating axis thereof. The brake disc 10, therefore, is also referred to as a rotor, or simply "a disc." The brake disc 10 may be either solid or ventilated disc.
The brake disc 10, as best shown in FIG. 1, includes at least one internal pocket 14 formed within the brake disc 10. It may herein be noted that the more that one internal pocket 14, may be provided on the brake disc 10, without deviating from the spirit of the present disclosure. The internal pocket 14 or the opening may be like a cavity within the brake disc 10, and is capable of being filled with a heat transfer fluid. Although in one embodiment of the present disclosure, the internal pocket 14 is shaped like a circular tube, positioned concentrically with respect to a

center of rotation of the brake disc 10, the internal pocket 14 may have any other profile without deviating from the spirit of the present disclosure. The heat transfer fluid may be a cooling medium like a mineral oil. The heat transfer fluid, in one embodiment of the present disclosure may be a low viscous high temperature (-650° C) saturation mineral oil. The cooling medium may be filled up to any predetermined volume level. The cooling medium may be either in liquid or semi-solid state. The cooling medium shall be mineral or non mineral oil and may be free flow or forced flow. The force for such forced flow may be provided by rotation of said ventilated brake disc 10 during vehicle movement. Alternatively, the force for such forced flow may be provided by external equipment.
The heat transfer fluid may be filled in the internal pocket 14 through an inlet passage 16. A screw 17 with a rubber seal is provided to block the inlet passage 16. In one embodiment of the present disclosure, the mineral oil is to be filled up to 80% of available volume. Thereafter, the inlet passage 16 is blocked using said screw with rubber seal. The screw can be removed for draining the mineral oil from the internal pocket 14. In alternative embodiments, there may be multiple the inlet passages, similar to the inlet passage 16.
Referring again to FIG. I and FIG 2, the disc brake system 100 includes a plurality of heat exchanger fins. As best visible in FIG. 1, the plurality of heat exchanger fins are the associated with the internal pocket and heat transfer fluid filled therein. In one embodiment the plurality of heat exchanger fins, also referred to as plurality of cooling fins, may include internal fins 18 and external fins 20. Each of the internal fins 18 and external fins 20 extend outwardly from the internal pocket 14, to the atmosphere. The plurality of heat exchanger fins may be of a predefined profile, based on the extent of heat transfer required.
More particularly, at least an end portion of each of the external fins 20 and internal fins 18 is positioned towards the atmosphere, to facilitate heat transfer.

An opposite end portion of each of the external fins 20 and internal fins are thermally coupled with the heat transfer fluid in the internal pocket 14. As best visible in FIG. 2, the disc brake system 100 includes a caliper assembly 22. The caliper assembly 22 is carried by the wheel hub 12. The caliper assembly 22 includes disc pads 24, capable of engaging with the brake disc 10 to resist rotational movement thereof. That is how the caliper assembly 22 stops or retards the vehicle.
During the utilization of the disc brake system 100, when the brake is applied, heat gets generated at the surface of brake disc 10. This generation of heat on the surface of brake disc 10 also occurs in evening conventional system, and is due to engagement of the brake disc 10 with the calipers pads 24 of the caliper assembly 22. This heat gets absorbed by mineral oil quickly due to its higher saturation temperature. The mineral oil, therefore acts as heat sinking element. In parallel, since the brake disc 10 is continuously rotating as vehicle is moving, heat from mineral oil is transferred to atmosphere through internal fins and external fins due to convection heat transfer between atmospheric air and fins. This phenomenon i.e. heat transfer from brake disc surface to mineral oil and from mineral oil to atmosphere occurs continuously. Since, the saturation temperature of mineral oil is very high, its heat absorption capacity is higher; this maintains the disc surface temperature lower. Fig.3 shows comparison of a conceptual oil filled disc and conventional ventilated disc temperature development and cooling characteristics for same test cycles.
The foregoing description provides specific embodiments of the present disclosure. It should be appreciated that these embodiment are described for purpose of illustration only, and that numerous other alterations and modifications may be practiced by those skilled in the art without departing from the spirit and scope of the disclosure. It is intended that all such modifications and alterations be included insofar as they come within the scope of the disclosure as claimed or the equivalents thereof.

Referral Numerals Description
100 Disc brake system
10 Brake disc
12 Wheel hub
14 Internal pocket
16 Inlet passage
17 Screw
18 Internal fins
20 External fins
22 Caliper assembly
24 Disc pads

We claim:
1. A disc brake system (100) for an automobile, the disc brake system (100)
comprising:
a brake disc (10) adapted to be mounted on a wheel hub (12) along a rotating axis thereof;
at least one internal pocket (14) formed within the brake disc (10), the at least one internal pocket (14) capable of being filled with a heat transfer fluid;
a plurality of heat exchanger fins (18) extending outwardly from the internal pocket (14) and thermally coupled with the heat transfer fluid filled in the internal pocket (14); and,
a caliper assembly (22) carried by the wheel hub (12), wherein the caliper assembly (22) being capable of selectively engaging with the brake disc (10) to resist the rotational movement thereof.
2. The disc brake system (100) as claimed in claim 1, wherein the heat generated because of engagement of the caliber assembly (22) and the brake disc (10) is transferred by the transfer fluid carried within the one internal pocket (14) and the plurality of heat exchanger fins (18), to the atmosphere.
3. The disc brake system (100) as claimed in claim 1, wherein the internal pocket (14) includes an inlet passage (16).
4. The disc brake system (100) as claimed in claim 3, wherein the passage (16) is capable of being sealed by a screw with rubber seal.
5. The disc brake system (100) as claimed in claim 1, wherein the plurality of heat exchanger fins (18) includes a set of external fins (18) and a set of internal fins (20).

6. The disc brake system (100) as claimed in claim 1, wherein the heat transfer fluid is a mineral oil.
7. A brake disc (10) for a disc brake system (100), the brake disc (10) comprising;
at least one internal pocket (14) formed within the brake disc (10), the at least one internal pocket (14) capable of being filled with a heat transfer fluid, the internal pocket includes an inlet passage (16);
a plurality of heat exchanger fins (18) formed on the internal pocket (14), such that the heat generated because of engagement of a caliber assembly (22) and the brake disc (10) is transferred, by the transfer fluid carried within the one internal pocket (14) and the plurality of heat exchanger fins (18), to the atmosphere.