FORM 2
THE PATENTS ACT, 1970
(39 of 1970) &
The Patents Rules, 2003
PROVISONAL COMPLETE SPECIFICATION
(See section 10 and rule 13)
1. TITLE OF THE INVENTION
Fuel Cooled Chassis for Airbome Electronics Engine Control Unit
2. APPLICANT(S)
(a) NAME: HINDUSTAN AERONAUTICS LIMITED
b) NATIONALITY: INDIAN
(c) ADDRESS: AGM (Design)-HOD RADAR, SLRDC, HAL, Hyderabad-500042.
3. PREAMBLE TO THE DESCRIPTION
PROVISIONAL The following COMPLETE The following specification
specification describes the invention. particularly describes the invention? and the manner in which is to be performed.

4. DESCRIPTION: Refer Annexure l
5. CLAIMS: Refer Annexure II
6. DATE AND SIGNATURE (to be given at the end of last page of specification)
7. ABSTRACT OF THE INVENTION: Refer Annexure III
Note:-
*Repeat boxes in case of more than one entry.
*To be signed by the applicant(s) or by authorized registered patent agent.
*Name of the applicant should be given in full, family name in the beginning.
*Complete address of the applicant should be given stating the postal index no.code, state and country.
*Strike out the column(s) which is/are not applicable.

Annexure-l
1. Title of Invention:
[001] Fuel Cooled Chassis for Airborne Electronics Engine Control Unit.
2. Field of Invention:
[002] The invention relates to a fuel—cooled chassis for an Airborne Electronics Engine Control Unit more particularly to thermal management of Electronics Engine Control Unit where in aircraft fuel is used as liquid coolant for peripheral cooling of chassis top side, right side and bottom sides of chassis for effective heat management and that include effective utilization of aircraft fuel as liquid coolant for liquid cooling, shielding, insulating, and simplified geometly with less components and ease of manufacturing features.

3. Background of Invention:

[003] Electronics Engine Control Unit (EECU) consists of electronic components and microcontroller chip (CPU) on a printed circuit board (PCB) along with electrica1 interface connectors are programmed to control propulsion engine system. EECU system generate a significant amount of heat. Ensuring efficient heat dissipation is critical to prevent overheating and system failures. EECU is mounted on the engine fan case inside the nacelle, high temperatures and high flow rate of ram will flow around its periphery. This results in high thermal loads on the EECU controller, necessitating effective heat management solutions.
Prevailing atmosphere conditions of EECU are at higher level compared to the LRUs generally placed in avionics bay. Hence sufficient differential temperature is not available to dissipate EECU system generated heat, also receives remarkable amount of heat from outside the EECU.

Conventional conduction cooling and forced air cooling will not help to protect PCB and components. In this scenario protecting the PCB
and components from external ambient is a prime focus besides heat dissipation from PCB and components. A cooling medium is necessary to extract the heat from both sides such that it acts as themal barrier to protect PCB and components. Therefore, peripheral cooling method using fuel as a cooling medium is adapted for thermal management of EECU. Aircraft engine already have a
fuel system in place, making it convenient to utilize pressurized fuel for cooling EECU system. This eliminates the need for separate cooling systems, reduces complexity and leverages the existing infrastnlcture.

3.1Prior Art
0820110271655A1:SEPARATE COOLING PLATE FOR
AIRCRAFT ENGINE ELECTRIC CONTROL
[004] This invention relates to a cooling plate for an aircraft electric control, wherein the cooling plate is maintained separate from the
control which is mounted to an engine. An electric element is mounted to a cooling plate that is in turn mounted to an outer housing of an engine. Engine controller has an electrical control including electrical connectors and electric circuits. The electric circuits are programmed to control an aircraft engine. The electrical control is attached to a cooling plate, which includes internal fluid passages for circulating a cooling fluid, and providing cooling to the electrical control.

U801095481432: SYSTEM WITH THIN WALLED COOLING
PLATE FOR AN ELECTRONIC ENCLOSURE

[005] The invention relates an electronic unit with an enclosure that has a thin walled cooling plate as a cover. An electronic circuit board is contained in the interior space and the cooling plate closes the open side. The cooling plate has a flow channel adjacent the inner side that is configured to channel a circulating fluid to remove heat from the electronic circuit boards. The outer side of the cold plate is anodized to block heat from entering inside the enclosure through the cooling plate.

4. Brief summary of Invention
[006] The fuel cooled chassis for airborne EECU is made out of mono block Aluminum, has cavities that encloses electronic components and PCBs along with electrical interface connectors, that are programmed to control propulsion engine system and is directly mounted on the engine fan case inside the nacelle. In a separate feature the chassis top surface, right surface and bottom surface form a "C" shaped cold plate, which includes internal flow path for circulation of pressurized aircraft fuel for liquid cooling. The requirement of compact, lighter and simple geometry for fuel cooled chassis imposes size and space constraint on cold plate, use of bigger cross section flow path is not feasible and use of smaller cross section will lead to higher flow path resistance, In a separate feature internal flow path for circulation of pressurized aircraft fuel is bifurcated carefully from fuel inlet on top surface till fuel outlet on bottom surface to optimize the flow path resistance without compromising flow requirements.

[007] Pressurized fuel as liquid coolant has to pass thru the internal flow path from inlet to outlet for peripheral cooling of chassis on top side, right side and bottom sides of chassis for effective utilization of aircraft fuel as liquid coolant for fluid cooling, shielding, insulating.

In a separate feature square / rectangular open channels on top and bottom surfaces are formed by conventional milling and channels on top and bottom surface are interconnected thru drilled holes of diameter equivalent channel parameters.

[008] Special emphasis is placed on channel parameters for appropriate flow and pressure drop. The Coolant is evenly distributed to all peripheral cooling components without localized pressure drops in certain areas. In a separate feature internal coolant flow paths are designed as smooth and streamlined as possible, minimizing sharp bends, abrupt transitions, and narrow passages. In a separate feature internal flow channels are formed by vacuum brazing a separate thin aluminum sheet both on top surface and bottom surface that completes the formation of one passage from inlet to the outlet

[009] Milled channels cold plates are customized and tailored to cooling requirement. Channels can be designed to different configurations and patterns to optimize the coolant flow and
maximize the heat transfer efficiency. Additionally, being machined from a single block of material provides better structural integrity
and improved thermal conductivity.

5. Brief description of drawings
[010] The features and other special characteristics and advancement of the current invention can be better explained with the accompanying drawings and appended claims where in each special feature is represented by a numeral

Figure: 1 shows exploded view of fuel cooled chassis assembly
Figure: 2&3 shows chassis top and bottom isometric view before brazing
Figure: 4 shows sectional view of cooling fluid flow on top surface
Figure: 5 shows sectional view of cooling fluid flow on bottom surface
Figure: 6 shows isometric view of chassis top surface along with partial cut section of thin aluminum plate after brazing
Figure: 7 shows isometric view of chassis top surface along with partial cut section of cooling fluid flow transition path from top surface to bottom surface after brazing
Figure: 8 shows exploded View of front panel sub assembly along with front panel PCB
Figure: 9 shows partial view of interconnections for stack connectors on electronic assemblies and front panel PCB with mother boards
Figure: 10 shows Front isometric View of Electronics Engine Control Unit (EECU) assembly along with electrical interface connectors

6. Detailed Description of Invention
[011] The fuel cooled chassis for airborne EECU comprises a mono block aluminum enclosure(1) with a openings on front and rear side, provided with suitable recesses to guide electronic assemblies.
Mother boards (2), Electronic assemblies for channel-A (3) and channel—B (4), Front panel sub assembly (5), Front panel PCBs(6) along with electrical interface connectors and a rear cover(7). The front panel assemb1y(5) along with front panel PCB(6) is aligned to mother board(2) by guide pins(8) which in turn fixed to the
receptacle hole(9) on the front face of enclosure(1)
[012]. The enclosure (1) has dual connecting parallel flow passages(28) starting from fuel inlet port(16) on the top surface(18) to fuel outlet port(17) on bottom surface( 19) and connected with inlet valve (29) and outlet valve(30). Flow passages (28) on top surface(18)
and bottom surface(19) are interconnected thru drilled cylindrical holes (23) on right side wall(20) of enclosure(1). If the cooling inlet
port(16) and outlet port(l7) are provided on top surface(18), fuel first will enter through inlet port(16) and flow through the internal
flow path on chassis top surface(18) and pass though cylindrical hole(23) drilled across right side surface(21) and pass through the
internal flow path on bottom surface(19) and eventually return to top surface( 18) though cylindrical hole(23) drilled across right side
surface(21) of the enclosure and again it will flow through the internal flow path on chassis top surface(18) and exit the enclosure (1) from outlet port (17). The fluid has to overcome potential head difference between bottom surface(19) and top surface(18) to reach from bottom surface to top surface, while returning which will increase the pressure loss in flow path. If the cooling inlet port(16) and outlet port(17) are provided on chassis bottom surface(19), fuel first will enter through inlet port(16) and flow through the internal flow path(28) on chassis bottom surface(19) and pass though cylindrical hole(23) drilled across right side surface(21) and pass through the internal flow path on top surface(18) and eventually return to bottom surface(19) though cylindrical hole(23) drilled across right side surface(21) and again it will flow through the
internal flow path on chassis bottom surface(22) and exit enclosure (1) from outlet port (17). The fluid has to overcome potential head difference between bottom surface(19) and top surface(18) while climbing from bottom surface(19) to top surface(18) which will increase the pressure loss in flow path.

[013] The inlet port(16) for fuel entry is provided on chassis top surface(l8) and outlet port(17) is provided on chassis bottom surface (19) so that the fuel will travel thru interconnected drilled cylindrical holes(23) on right side wall of the enclosure(1) using
gravity. Total pressure drop is minimized from inlet port to outlet port. In a separate feature the chassis top surface(18), right surface(21) and bottom surface(19) form a "C" Shaped cold plate,
which includes internal flow passage for circulation of pressurized aircraft fuel for liquid cooling.

[014] Aluminium enclosure(1) has four legs(33) with circular openings to align and secure vibration dampers(32). Upon assembly vibration dampers(32) receive bolted members to mount EECU directly on the engine frame.

[015] The requirement of compact, lighter and simple geometry for fuel cooled chassis imposes size and space constraint on cold plate, use of bigger cross section flow path is not feasible and use of smaller cross section will lead to higher flow path resistance, In a separate feature a shrouded angular thin wan section (25) is formed at entry and exit ports that facilitates the smooth bifurcation of fluid flow into the passages at entry and seamless exit with no turbulence at exit ports(17). In a separate arrangement to make chassis lighter without compromising structural integrity excessive material removed in the form of weight reduction pockets.

[016] In a separate feature The flow passages (28) on top(18) and bottom surfaces(19) are formed by conventional milling and are interconnected thru drilled holes(23) of diameter equivalent flow
passage parameters. Peripheral cooling requires maximum coverage of chassis surface by cooling fluid, which will create more pressure drop due to flow path resistance. The fuel flow passage is a
customized and configured path having U shaped & L shaped bends with smooth curvatures on top and bottom sides of enclosure(1) to cover effective areas to provide peripheral cooling, specific to heat load generated by internal electronic assemblies.

Special emphasis is given to flow passage parameters for appropriate flow and pressure drop. The coolant is evenly distributed to all
peripheral cooling components without localized pressure drops.
The flow passages, open till now, are formed a closed continuous channel passages by vacuum brazing a separate aluminum sheet(24) of required thickness both on top surface(18) and bottom surface(19).

[017] Milled channels cold plates are customized and tailored to cooling requirement. Channels can be designed to different configurations and patterns to optimize the coolant flow and maximize the heat transfer efficiency. Additionally, being machined from a single block of material provides better structural integrity and improved thermal conductivity.
[018] In a separate feature, enclosure has cavities that encloses electronic components and PCBs along with electrical interface connectors, that are programmed to control propulsion engine
system.
[019]Mother board(2) has high density stack connector receptacles on both front side and fear side. Electronics assemblies for channel
A(2) and channei—B(3) will have high density stack connector plugs to be aligned with high density stack connector receptacles on rear side of mother board, when housed, positioned and secured in enclosure(1).-Front panel PCB(6) will have plurality of high density stack connector plugs on rear side and plurality of interface connectors on front side.
[020] In a separate feature the fuel while circulation through the internal flow line will form a C-shaped cold jacket around the internal PCBs and its components. The circulating fluid will extract heat generated from internal electronics and also the heat from ram air that is passing over the ECCU. In addition to cooling effect provided it also act as shielding and insulating medium as well. The special features and other functional details as elaborated in the detailed description of the current invention can be well established by the enclosed claims.

7.CLAIMS
Title: Fuel Cooled Chassis for Airborne Electronics Engine Control Unit.

We claim:

1)A fuel cooled chassis for airborne Airborne Electronics Engine
Control Unit (EECU) comprising:
a mono block aluminum enclosure (1) with openings on front and
rear side;
at least one Mother board (2), electronic assemblies for channel-
A (3) and a channel-B (4);
a front panel sub assembly (4), a front panel PCB (5) along with
electrical interface connectors and a rear cover (6); and
wherein said enclosure having closed rectangular flow passages
(28) on either side of enclosure forming C—shaped continuous
flow path by interconnecting holes and has mounting lugs and guiding recesses.

2)The fuel cooled chassis for airborne EECU as claimed in claim 1, wherein said C—shaped flow passage has at least one fuel inlet, one fuel outlet and a dual parallel flow passage pattern (28) having U shaped 81. L shaped bends with smooth curvatures on top and bottom surfaces, inter connected by vertical holes (23) forming continuous C-shaped flow passage.

3)The fuel cooled chassis for airborne EECU as claimed in claim 1 and 2, wherein said dual parallel flow passage contains a shrouded angular thin wall section (25) at entry and exit ports that facilitates the smooth bifurcation of fluid flow into the passages at entry and seamless exit with no turbulence at exit ports.

4)4) The fuel cooked chassis for airborne EECU as claimed in claim 1, wherein said Aluminium enclosure (1) having four legs (33) with circular openings to align and secure vibration dampers (32).

5) The fuel cooled chassis for airborne EECU as claimed in claim 1, 5 wherein said Aluminium enclosure have recess to receive the guide pins(8) on front panel assembly (5) for guiding and securing the front panel to the enclosure(1).
6) The fuel cooled chassis for airborne EECU as claimed in claim 1, wherein said Aluminium enclosure has four cavities, separated 10 by enclosure walls, having suitable recesses for electronics assemblies for channel-A(2) and channel-8(3), wherein the said walls provide mechanical isolation between electronics assemblies. ,
7) The fuel cooled chassis for airborne EECU as claimed in claim 1 15 and 2, wherein said Flow passages are produced by attaching a separate aluminum sheet(34) by vacuum brazing process on either side of enclosure(1).
8) The fuel cooled chassis for airborne EECU as claimed in claim 1, wherein said Mother board (2), when'housed, positioned and 20 secured in enclosure (1) will act as a means for stacking electronics assembles and front panel assembly.