FORM – 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
(See section 10 and rule 13)
THERMO-MECHANICALLY ACTUATED BRAKE DRUM COOLING
SYSTEM FOR A COMMERCIAL VEHICLE
Applicant(s):
VE COMMERCIAL VEHICLES LTD
102, INDUSTRIAL AREA 1, PITHAMPUR- 454775, DIST. DHAR, MP, INDIA
Inventors:
Pradunmya Pran Dutta
The following specification particularly describes the invention and the manner
in which it is to be performed.
2
THERMO-MECHANICALLY ACTUATED BRAKE DRUM COOLING
SYSTEM FOR A COMMERCIAL VEHICLE
FIELD OF THE DISCLOSURE
5 [0001] The present invention relates generally to the field of vehicle brake cooling
system, and more particularly to a thermo-mechanically actuated brake drum cooling
system for a commercial vehicle.
BACKGROUND OF THE INVENTION
10 [0002] The subject matter discussed in the background section should not be assumed
to be prior art merely as a result of its mention in the background section. Similarly, a
problem mentioned in the background section or associated with the subject matter of
the background section should not be assumed to have been previously recognized in
the prior art. The subject matter in the background section merely represents different
15 approaches, which in and of themselves may also correspond to implementations of the
claimed technology.
[0003] Commercial vehicle drum brake systems are routinely exposed to high thermal
stresses during prolonged braking, particularly in downhill driving, dense urban stopand-go traffic, and high-payload duty cycles. Continuous frictional engagement
20 between the brake shoes and the rotating drum generates significant heat, which can
elevate drum temperatures beyond optimal operating limits. Excessive heat leads to
brake fade, reduction in friction coefficient, increased stopping distance, thermal
distortion of the drum, lining glazing, and accelerated wear of associated components.
Over time, such thermal degradation compromises braking efficiency, vehicle safety,
25 and maintenance intervals.
[0004] Conventional brake cooling approaches typically employ fixed passive ducts or
louvers that provide constant airflow irrespective of brake temperature. These
3
arrangements fail to dynamically enhance cooling during high-temperature events and
may permit unnecessary ingress of dust, mud, and water during normal or lowtemperature operation. Alternatively, active cooling systems incorporating electrically
powered fans, temperature sensors, wiring harnesses, and electronic control modules
5 add cost, structural complexity, and additional failure modes, particularly in harsh
commercial vehicle environments. Accordingly, there exists a need for a temperatureresponsive, self-regulating brake cooling mechanism capable of increasing airflow only
when required, without relying on electrical power or electronic control systems,
thereby improving braking safety, performance, and durability.
10 [0005] According to the patent application number “US20220145950A1” titled “Drum
brake for vehicle”, discloses a drum brake for a vehicle includes a drum rotating
together with a wheel of the vehicle, a pair of brake shoes generating a braking force
by friction with an inner surface of the drum, and a wheel cylinder provided between
one ends of the pair of brake shoes to operate the pair of brake shoes outwardly, wherein
15 the wheel cylinder includes a pair of pistons configured to press and release the pair of
brake shoes, a cylinder configured to accommodate the pair of pistons movable forward
and backward, and a pair of sealing members inserted into annular recessed grooves
formed on an inner surface of the cylinder, and each of the sealing members returns the
pair of pistons when a pressure of the pistons is released
20 [0006] According to another patent application number “US5553691A” titled
“Mechanically actuated drum brake”, drum brake having a support plate (10) with first
and second shoes (12,14) slidably mounted thereon. Each of the shoes (12,14) having
a web (12a,14a) and a rim (12b,14b) with a face for receiving a friction lining (16,18).
Each web (12a,14a) has a first end and a second end. The rim holds the friction lining
25 in a position to engage a drum (20) in response to an input force applied to the first end
of the webs (12a,14a) of the shoes (12,14) by a hydraulic actuation device (22). A
bearing member (28) is secured to the support plate (10) and is connected to a second
end of the webs (12a,14a). A spacer device (40) arranged in the vicinity of the hydraulic
4
device has a variable length to establish a spacing between the shoes (12,14) and drum
(20). A mechanical actuation device (50) secured to a web (14a) of shoe (14) has a first
actuation lever (60) and a second lever (70). A force applied to the first lever (60) is
articulated through the second lever to act on the web (12a) of shoe (12) such that a
5 brake force is substantially distributed to bring each friction lining (16,18) into
engagement with the drum (20) and effect a brake application.
[0007] Therefore, there is a need of a thermo-mechanically actuated brake drum
cooling system for a commercial vehicle.
OBJECTIVES OF THE INVENTION
10 [0008] An objective of the invention is to provide a thermo-mechanically actuated
brake drum cooling system for a commercial vehicle.
[0009] Furthermore, the objective of the invention is to provide a method of operating
a thermo-mechanically actuated brake drum cooling system for a commercial vehicle.
[0010] Furthermore, the objective of the invention is to provide a thermo-mechanically
15 actuated brake drum cooling system capable of automatically increasing cooling
airflow in response to elevated brake temperature.
[0011] Furthermore, the objective of invention is to provide the thermo-mechanically
actuated brake drum cooling system having temperature-proportional airflow
modulation mechanism using a thermo-bimetal actuator that operates without electrical
20 power, temperature sensors, electronic control units, wiring harnesses, or software.
[0012] Furthermore, the objective of the present invention is to reduce brake fade,
thermal degradation, drum distortion, and associated safety risks during prolonged or
high-load braking conditions in commercial vehicles.
[0013] Furthermore, the objective of the present invention is to maintain the cooling
25 duct in a substantially closed state during low or moderate temperature operation,
thereby minimizing ingress of dust, mud, and water into the brake assembly.
5
SUMMARY
[0014] The invention relates to a thermo-mechanically actuated brake drum cooling
system for a commercial vehicle.
[0015] According to an aspect, a thermo-mechanically actuated brake drum cooling
5 system for a commercial vehicle. Further, the system comprising a duct body
configured to be mounted adjacent to a brake drum and to channel external airflow
toward the brake drum. Further, a flap pivotally mounted to the duct body about a hinge
axis and movable between a closed position restricting airflow and an open position
increasing airflow. Further, a thermo-bimetal actuator disposed within the duct body
10 and positioned adjacent to the hinge axis of the flap, the thermo-bimetal actuator being
mechanically coupled to the flap. Further, a mounting interface formed on the duct body
and configured for attachment to an axle support structure of the vehicle. Further, the
thermo-bimetal actuator comprises a bonded bi-layer metallic strip formed of two
metallic layers having different coefficients of thermal expansion. Further, thermal
15 radiation and convective heat from the brake drum cause differential thermal expansion
of the metallic layers resulting in bending of the thermo-bimetal actuator, such bending
directly rotating the flap toward the open position to increase an inlet area of the duct
body in proportion to brake temperature.
[0016] According to another aspect, a method of operating a thermo-mechanically
20 actuated brake drum cooling system for a commercial vehicle, comprising the steps of
mounting a duct body adjacent to the brake drum such that the duct body channels
external airflow toward the brake drum. Further, pivotally mounting a flap to the duct
body about a hinge axis, the flap being movable between a closed position restricting
airflow and an open position increasing airflow. Further, disposing a thermo-bimetal
25 actuator within the duct body adjacent to the hinge axis and mechanically coupling the
thermo-bimetal actuator to the flap. Further, exposing the thermo-bimetal actuator to
thermal radiation and convective heat generated by the brake drum during braking.
Further, causing differential thermal expansion of two bonded metallic layers of the
6
thermo-bimetal actuator having different coefficients of thermal expansion. Further,
bending the thermo-bimetal actuator in response to the differential thermal expansion;
and directly rotating the flap toward the open position by the bending of the thermobimetal actuator, thereby increasing an inlet area of the duct body in proportion to brake
5 temperature.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] The accompanying drawings illustrate the embodiment of the system. Any
person with ordinary skills in the art will appreciate that the illustrated element
boundaries (e.g., boxes, groups of boxes, or other shapes) in the figures represent one
10 example of the boundaries. It may be that in some examples one element may be
designed as multiple elements or that multiple elements may be designed as one
element. In some examples, an element shown as an internal component of one element
may be implemented as an external component in another, and vice versa. Furthermore,
elements may not be drawn to scale. Non-limiting and non-exhaustive descriptions are
15 described with reference to the following drawings. The components in the figures are
not necessarily to scale, emphasis instead being placed upon illustrating principles.
[0018] FIG. 1 illustrates a block diagram of a thermo-mechanically actuated brake
drum cooling system for a commercial vehicle, according to an embodiment of the
present invention;
20 [0019] FIG. 2 illustrates a process flow chart of the thermo-mechanically actuated
brake drum cooling system for a commercial vehicle, according to an embodiment of
the present invention; and
[0020] FIG. 3 illustrates a method of operating a thermo-mechanically actuated brake
drum cooling system for a commercial vehicle, according to an embodiment of the
25 present invention.
7
DETAILED DESCRIPTION OF THE INVENTION
[0022] Some embodiments of this disclosure, illustrating all its features, will now be
discussed in detail. The words “comprising,” “having,” “containing,” and “including,”
and other forms thereof, are intended to be equivalent in meaning and be open ended in
5 that an item or items following any one of these words is not meant to be an exhaustive
listing of such item or items or meant to be limited to only the listed item or items. It
must also be noted that as used herein and in the appended claims, the singular forms
“a,” “an,” and “the” include plural references unless the context clearly dictates
otherwise.
10 [0023] Although any systems and methods similar or equivalent to those described
herein can be used in the practice or testing of embodiments of the present disclosure,
the preferred, systems and methods are now described. Embodiments of the present
disclosure will be described more fully hereinafter with reference to the accompanying
drawings in which like numerals represent like elements throughout the several figures,
15 and in which example embodiments are shown. Embodiments of the claims may,
however, be embodied in many different forms and should not be construed as limited
to the embodiments set forth herein. The examples set forth herein are non-limiting
examples and are merely examples among other possible examples.
[0024] The present invention discloses a thermo-mechanically actuated brake drum
20 cooling system for a commercial vehicle.
[0025] FIG. 1 illustrates a block diagram of a thermo-mechanically actuated brake
drum cooling system (100) for a commercial vehicle, according to an embodiment of
the present invention.
[0026] In some embodiments, a thermo-mechanically actuated brake drum cooling
25 system (100) comprises a duct body (102), brake drum (104), flap (106), thermobimetal actuator (108), and bi-layer metallic strip (110).
[0027] In some embodiments, the thermo-mechanically actuated brake drum (104)
cooling system (100) comprises a duct body (102) configured to be mounted adjacent
8
to a brake drum (104) of a commercial vehicle. The duct body (102) is configured to
channel external airflow toward the brake drum (104) to enhance convective heat
dissipation. The duct body (102) is shaped to direct ambient air toward a surface region
of the rotating brake drum (104) during vehicle motion. The duct body (102) may be
5 positioned to capture ram air generated during forward travel of the vehicle. The duct
body (102) is configured to operate without electrical assistance or powered airflow
generation. The duct body (102) forms a structural housing for a temperatureresponsive flap (106) mechanism. The arrangement enables passive airflow guidance
during braking events. The duct body (102) supports integration with existing brake
10 assemblies.
[0028] In some embodiments, the system (100) further comprises a flap (106) pivotally
mounted to the duct body (102) about a hinge axis and movable between a closed
position and an open position. The closed position restricts airflow entry into the duct
body (102) during low-temperature conditions. The open position increases airflow
15 toward the brake drum (104) during elevated temperature operation. The hinge axis
permits rotational movement of the flap (106) in response to mechanical actuation. The
flap (106) is dimensioned to substantially cover an inlet region of the duct body (102)
when closed. The pivotal arrangement enables repeatable and smooth angular
displacement. The flap (106) is configured to operate without powered actuators or
20 electronic control elements. The flap (106) supports temperature-dependent airflow
modulation.
[0029] In some embodiments, thermo-bimetal actuator (108) is disposed within the
duct body (102) and positioned adjacent to the hinge axis of the flap (106). The thermobimetal actuator (108) is mechanically coupled to the flap (106) to transmit bending
25 motion directly to rotational movement. In some embodiments, the thermo-bimetal
actuator (108) comprises a bonded bi-layer metallic strip (110) formed of two metallic
layers having different coefficients of thermal expansion. Differential thermal
expansion between the metallic layers causes bending when exposed to heat. The
9
actuator is arranged to convert thermal input into mechanical displacement without
intermediate components. The thermo-bimetal actuator (108) is mounted such that it
experiences heat radiated from the brake drum (104). The positioning enables
responsive actuation during braking events. The mechanical coupling ensures direct
5 and proportional flap (106) rotation.
[0030] In some embodiments, the thermo-bimetal actuator (108) is positioned within
the duct body (102) such that it is directly exposed to heated airflow originating from
the brake drum (104). The exposure enables the actuator to respond to both radiative
heat and convective heat transfer. The actuator is located in proximity to the hinge axis
10 to minimize mechanical losses. The thermal response is initiated when brake
temperature rises during prolonged or repeated braking. The bending of the thermobimetal actuator (108) occurs progressively as temperature increases. The arrangement
ensures that flap (106) displacement corresponds to actual brake thermal conditions.
Direct exposure improves sensitivity and response time. The configuration enhances
15 reliability in harsh operating environments.
[0031] In some embodiments, the angular displacement of the flap (106) is proportional
to the degree of thermal deflection of the thermo-bimetal actuator (108). As brake
temperature increases, the magnitude of bending increases correspondingly. The
proportional bending directly rotates the flap (106) toward the open position. The open
20 position increases an inlet area of the duct body (102) in proportion to brake
temperature. Airflow through the duct body (102) increases progressively as brake
temperature rises. The proportional response creates a self-regulating cooling
mechanism. The system (100) provides enhanced convective cooling during hightemperature conditions. The absence of stepped or discrete control ensures smooth
25 modulation. The arrangement supports consistent thermal management.
[0032] In some embodiments, the flap (106) is biased toward the closed position by
inherent elastic recovery of the thermo-bimetal actuator (108) upon temperature
reduction. When brake temperature decreases, the bi-layer metallic strip (110) contract
10
and return toward their original configuration. The elastic recovery generates reverse
rotational movement of the flap (106) toward the closed position. The closed position
substantially seals the duct inlet during low-temperature operation. The sealing limits
ingress of dust, mud, and water into the brake assembly. The biasing action occurs
5 without springs, motors, or additional mechanical biasing elements. The thermobimetal actuator (108) thus performs both opening and closing functions. The inherent
recovery ensures repeatable operation over multiple cycles. The arrangement enhances
durability and simplicity.
[0033] In some embodiments, the system (100) further comprises a mounting interface
10 formed on the duct body (102) and configured for attachment to an axle support
structure of the vehicle. The mounting interface enables secure installation adjacent to
the brake drum (104) without modification of the drum structure. In some
embodiments, the mounting interface allows retrofit installation on existing commercial
vehicles. The interface may include fastening provisions compatible with standard axle
15 supports. The structural arrangement maintains alignment between the duct body (102)
and the brake drum (104). The mounting configuration ensures stable positioning
during vehicle vibration and road shocks. The system (100) operates without electrical
wiring, sensors, or control modules. The architecture provides a robust and lowcomplexity installation.
20 [0034] In operation, thermal radiation and convective heat generated by the brake drum
(104) during braking are transmitted to the thermo-bimetal actuator (108). The heat
causes differential thermal expansion of the bonded metallic layers. The resulting
bending motion directly rotates the flap (106) toward the open position. The increase in
inlet area permits greater external airflow to reach the brake drum surface. The
25 increased airflow enhances convective cooling and reduces brake fade and thermal
degradation. Upon cessation of braking and reduction of temperature, the actuator cools
and returns toward its original shape. The flap (106) correspondingly moves toward the
closed position. The entire process occurs without hydraulic, electrical, or electronic
11
components. The system (100) provides passive, temperature-proportional cooling
regulation for commercial vehicle brake drums.
[0035] FIG. 2 illustrates a process flow chart (200) of the thermo-mechanically
actuated brake drum cooling system (100) for a commercial vehicle, according to an
5 embodiment of the present invention.
[0036] At step 202, the vehicle is in motion under normal operating conditions. During
forward movement, ambient air flows around the wheel assembly and the brake region.
The cooling duct remains in a substantially closed condition when brake temperatures
are low. The thermo-bimetal actuator (108) is in its neutral state. No additional airflow
10 modulation is required at this stage. The system (100) remains passive and inactive in
terms of flap (106) movement. The duct is positioned to receive airflow when required.
[0037] At step 204, the brake is applied by the driver, initiating frictional engagement
between the brake shoe and the rotating brake drum (104). This friction generates
thermal energy at the contact interface. The generated heat begins to accumulate within
15 the brake drum (104) structure. The braking event may occur during downhill driving,
high load operation, or repeated stop conditions. The cooling duct remains responsive
to thermal changes. Heat transfer toward surrounding components begins.
[0038] At step 206, the brake temperature increases by a measurable temperature rise
(ΔT). The elevated temperature produces both thermal radiation and heated convective
20 airflow around the brake assembly. The temperature rise represents the triggering
condition for passive actuation. Heat energy propagates outward from the drum surface.
The thermal environment inside the duct body (102) begins to change. The system (100)
transitions toward an active cooling phase.
[0039] At step 208, the thermo-bimetal actuator (108) responds to the heat generated
25 by the brake drum (104). The actuator, positioned within the duct body (102), is
exposed to radiative and convective heat. The bonded bi-layer metallic strip (110)
absorbs thermal energy. Because the metallic layers have different coefficients of
12
thermal expansion, differential expansion occurs. The actuator begins to deform in a
controlled manner. The response is purely thermal and requires no electrical input.
[0040] At step 210, the bi-layer metallic strip (110) bends due to the increase in
temperature. The differential expansion between the two metallic layers creates a
5 curvature in the strip. The degree of bending corresponds to the magnitude of
temperature rise. This bending motion is progressive rather than abrupt. The actuator
converts thermal energy directly into mechanical displacement. The mechanical
deformation becomes sufficient to actuate the flap mechanism.
[0041] At step 212, the flap (106) rotates toward the open position due to mechanical
10 coupling with the bending thermo-bimetal actuator (108). The rotation occurs about the
hinge axis of the flap (106). The angular displacement is proportional to the actuator
deflection. As temperature increases further, the flap (106) opens more widely. The
opening enlarges the inlet area of the duct body (102). The system (100) begins actively
enhancing airflow without powered components.
15 [0042] At step 214, directed airflow is established through the duct body (102). The
increased inlet area allows external air to be guided toward the brake drum (104)
surface. The duct geometry channels the airflow in a focused manner. The airflow
direction improves heat transfer efficiency. The cooling mechanism relies on vehicle
motion and pressure differential. No fans or blowers are used.
20 [0043] At step 216, ambient cool air enters the duct body (102) and flows toward the
heated brake drum (104). The airflow increases convective heat removal from the drum
surface. The thermal gradient between the drum and ambient air enhances cooling
effectiveness. The airflow rate increases proportionally with flap opening. The system
(100) thereby provides temperature-dependent cooling enhancement. The cooling
25 process begins reducing accumulated heat.
[0044] At step 218, the directed airflow cools down the brake drum (104). Heat
dissipation occurs through convection into the surrounding air stream. The drum
temperature gradually decreases as braking demand reduces or cooling continues. The
13
improved airflow mitigates brake fade and thermal distortion. The system (100)
maintains proportional cooling response. Thermal equilibrium begins to be restored.
[0045] At step 220, the brake temperature drops to a lower level. As temperature
reduces, the thermo-bimetal actuator (108) cools and undergoes elastic recovery. The
5 bonded metallic layers contract toward their original dimensions. The bending
curvature decreases proportionally. The mechanical displacement transmitted to the
flap (106) is reduced. The system (100) transitions back toward a restricted airflow
state.
[0046] At step 222, the flap (106) closes proportionally to the temperature decrease.
10 The inherent elastic recovery of the thermo-bimetal actuator (108) rotates the flap (106)
toward the closed position. The duct inlet becomes substantially sealed during lowtemperature operation. This closure limits ingress of dust, mud, and water into the brake
assembly. The system (100) returns to its standby passive state. The entire cycle
operates without electrical power, sensors, or electronic control units.
15 [0047] FIG. 3 illustrates a method (300) of operating a thermo-mechanically actuated
brake drum (104) cooling system (100) for a commercial vehicle, according to an
embodiment of the present invention.
[0048] At step 302, a duct body (102) is installed adjacent to the brake drum (104) of
the vehicle such that it is structurally supported and properly aligned with the brake
20 assembly. The duct body (102) is oriented to capture ambient airflow generated during
vehicle motion. The positioning ensures that external air may be channelled efficiently
toward the outer surface of the brake drum (104). The mounting may be achieved
through a mounting interface configured for attachment to an axle support structure.
Proper alignment ensures optimal airflow direction and minimal obstruction. The duct
25 body (102) serves as the primary housing for the temperature-responsive mechanism.
This arrangement establishes the foundational airflow pathway for subsequent cooling
operation.
14
[0049] At step 304, a flap (106) is pivotally secured to the duct body (102) such that it
can rotate about a defined hinge axis. The flap (106) is configured to move between a
closed position, where airflow into the duct is restricted, and an open position, where
airflow is increased. The hinge arrangement permits smooth angular displacement with
5 minimal friction. The flap (106) is dimensioned to substantially cover the duct inlet
when in the closed position. The pivotal mounting enables repeatable and controlled
movement. The flap (106) acts as the airflow regulating component of the system (100).
This structural arrangement enables temperature-dependent airflow modulation.
[0050] At step 306, a thermo-bimetal actuator (108) is positioned within the duct body
10 (102) adjacent to the hinge axis of the flap (106). The actuator is mechanically linked
to the flap (106) so that bending motion of the actuator is directly transmitted to
rotational movement of the flap (106). The proximity to the hinge axis reduces
mechanical losses and improves response accuracy. The mechanical coupling may be
achieved through direct attachment or linkage mechanisms. The actuator is securely
15 retained within the duct housing. The configuration ensures that thermal deformation
results in immediate flap displacement. This step establishes the thermal-to-mechanical
conversion pathway.
[0051] At step 308, the thermo-bimetal actuator (108) is subjected to heat generated by
the brake drum (104) during braking events. Thermal radiation from the heated drum
20 surface and convective hot air flow within the duct region reach the actuator. The
actuator is positioned to ensure direct exposure to this thermal energy. The exposure
allows the actuator to sense actual brake temperature conditions. No electrical sensors
or temperature probes are required. The thermal input acts as the sole triggering
mechanism. This step initiates passive actuation of the system (100).
25 [0052] At step 310, the thermo-bimetal actuator (108) undergoes differential expansion
due to the distinct coefficients of thermal expansion of its bonded metallic layers. As
temperature rises, one metallic layer expands more than the other. This unequal
expansion creates internal stress within the bonded strip. The stress results in controlled
15
curvature of the actuator. The magnitude of differential expansion corresponds to the
temperature increase. The process is continuous and proportional. This step converts
thermal energy into mechanical deformation.
[0053] At step 312, the internal stresses generated by differential expansion cause the
5 thermo-bimetal strip to bend in a predictable direction. The bending curvature increases
progressively with rising temperature. The mechanical deformation is smooth and
proportional rather than abrupt. The bending motion represents the actuation output of
the thermal input. The thermo-bimetal actuator (108) is operates without springs,
motors, or auxiliary biasing components. The deformation is reversible upon cooling.
10 This step produces the mechanical movement required to actuate the flap (106).
[0054] At step 314, the bending of the thermo-bimetal actuator (108) is mechanically
transferred to the flap (106), causing it to rotate about the hinge axis toward the open
position. The angular displacement increases the effective inlet area of the duct body
(102). As the inlet area enlarges, greater ambient airflow is permitted to pass through
15 the duct toward the brake drum (104). The increase in airflow is proportional to brake
temperature due to proportional bending of the actuator. This results in enhanced
convective cooling of the brake drum (104) during high-temperature conditions. The
system (100) thus provides automatic, passive, temperature-responsive airflow
regulation without electrical power or electronic control systems.
20 [0055] It has thus been seen that the thermo-mechanically actuated brake drum cooling
system (100) for a commercial vehicle as described. The thermo-mechanically actuated
brake drum cooling system (100) for a commercial vehicle in any case could undergo
numerous modifications and variants, all of which are covered by the same innovative
concept; moreover, all of the details can be replaced by technically equivalent elements.
25 In practice, the components used, as well as the numbers, shapes, and sizes of the
components can be whatever according to the technical requirements. The scope of
protection of the invention is therefore defined by the attached claims.

Claims

1. A thermo-mechanically actuated brake drum cooling system (100) for a
5 commercial vehicle, the system (100) comprising:
a duct body (102) configured to be mounted adjacent to a brake drum
(104) and to channel external airflow toward the brake drum (104);
a flap (106) pivotally mounted to the duct body (102) about a hinge axis
and movable between a closed position restricting airflow and an open position
10 increasing airflow;
a thermo-bimetal actuator (108) disposed within the duct body (102)
and positioned adjacent to the hinge axis of the flap (106), the thermo-bimetal
actuator (108) being mechanically coupled to the flap (106); and
a mounting interface formed on the duct body (102) and configured for
15 attachment to an axle support structure of the vehicle,
wherein the thermo-bimetal actuator (108) comprises a bonded bi-layer
metallic strip (110) formed of two metallic layers having different coefficients
of thermal expansion,
and wherein thermal radiation and convective heat from the brake drum
20 (104) cause differential thermal expansion of the metallic layers resulting in
bending of the thermo-bimetal actuator (108),
such bending directly rotating the flap (106) toward the open position
to increase an inlet area of the duct body (102) in proportion to brake
temperature.
2. The thermo-mechanically actuated brake drum cooling system (100) as claimed
in claim 1, wherein the thermo-bimetal actuator (108) is positioned within the
duct body (102) such that it is directly exposed to heated airflow originating
from the brake drum (104).
3. The thermo-mechanically actuated brake drum cooling system (100) as claimed
in claim 1, wherein an angular displacement of the flap (106) is proportional to
a degree of thermal deflection of the thermo-bimetal actuator (108).
4. The thermo-mechanically actuated brake drum cooling system (100) as claimed
in claim 1, wherein the flap (106) is biased toward the closed position by
inherent elastic recovery of the thermo-bimetal actuator (108) upon temperature
reduction.
5. The thermo-mechanically actuated brake drum cooling system (100) as claimed
in claim 1, wherein the flap (106) substantially seals a duct inlet when in the
closed position to limit ingress of dust, mud, and water during low-temperature
operation.
6. The thermo-mechanically actuated brake drum cooling system (100) as claimed
in claim 1, wherein the flap (106) is biased toward the closed position by
inherent elastic recovery of the thermo-bimetal actuator (108) upon temperature
reduction.
7. The thermo-mechanically actuated brake drum cooling system (100) as claimed
in claim 1, wherein airflow through the duct body (102) increases progressively
as brake temperature rises, thereby enhancing convective cooling of the brake
drum (104).
8. The thermo-mechanically actuated brake drum cooling system (100) as claimed
in claim 1, wherein the thermo-bimetal actuator (108) directly converts brake-
generated thermal energy into mechanical rotational movement of the flap
(106) without intermediate hydraulic or electrical components.
9. A method of operating a thermo-mechanically actuated brake drum cooling
system (100) for a commercial vehicle, comprising the steps of:
mounting a duct body (102) adjacent to the brake drum (104) such that
the duct body (102) channels external airflow toward the brake drum (104);
pivotally mounting a flap (106) to the duct body (102) about a hinge
axis, the flap (106) being movable between a closed position restricting airflow
and an open position increasing airflow;
disposing a thermo-bimetal actuator (108) within the duct body (102)
adjacent to the hinge axis and mechanically coupling the thermo-bimetal
actuator (108) to the flap (106);
exposing the thermo-bimetal actuator (108) to thermal radiation and
convective heat generated by the brake drum (104) during braking;
causing differential thermal expansion of two bonded metallic layers of
the thermo-bimetal actuator (108) having different coefficients of thermal
expansion;
bending the thermo-bimetal actuator (108) in response to the differential
thermal expansion; and
directly rotating the flap (106) toward the open position by the bending
of the thermo-bimetal actuator (108), thereby increasing an inlet area of the duct
body (102) in proportion to brake temperature.