Load bearing element and a method for manufacturing a load bearing element
10081431 ยท 2018-09-25
Assignee
Inventors
- Oliver Seack (Bremen, DE)
- Matthias Hegenbart (Ahlerstedt, DE)
- Hermann Benthien (Sottrum, DE)
- Markus Piesker (Lueneburg, DE)
- Jens Rohde (Bremen, DE)
- Sebastian Palm (Bremen, DE)
- Joern Clausen (Hamburg, DE)
- Matthias Radny (Hamburg, DE)
- Ulrich Knapp (Hamburg, DE)
Cpc classification
F28D2021/0021
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F28F1/40
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
B22F10/18
PERFORMING OPERATIONS; TRANSPORTING
B64D41/00
PERFORMING OPERATIONS; TRANSPORTING
F28F13/14
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F28F1/422
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
B22F10/28
PERFORMING OPERATIONS; TRANSPORTING
B33Y80/00
PERFORMING OPERATIONS; TRANSPORTING
B64D27/402
PERFORMING OPERATIONS; TRANSPORTING
B22F10/25
PERFORMING OPERATIONS; TRANSPORTING
Y02T50/40
GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
B64C1/403
PERFORMING OPERATIONS; TRANSPORTING
B64D2041/002
PERFORMING OPERATIONS; TRANSPORTING
F28F13/185
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
B60R13/0869
PERFORMING OPERATIONS; TRANSPORTING
Y02P10/25
GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
International classification
F28F1/40
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
B64C1/40
PERFORMING OPERATIONS; TRANSPORTING
B64D41/00
PERFORMING OPERATIONS; TRANSPORTING
F28F1/42
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F28F13/14
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
B33Y80/00
PERFORMING OPERATIONS; TRANSPORTING
F28D21/00
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
B22F3/105
PERFORMING OPERATIONS; TRANSPORTING
B60R13/08
PERFORMING OPERATIONS; TRANSPORTING
Abstract
A load bearing element for attachment of a heat generating unit to a heat sensitive supporting structure, wherein said load bearing element includes at least one body integrally formed by additive layer manufacturing, ALM. The body is adapted to provide a controlled heat transfer from said heat generating unit to said heat sensitive supporting structure.
Claims
1. A combination of a heat generating unit, a heat sensitive supporting structure and a load bearing element for attachment of the heat generating unit to the heat sensitive supporting structure, wherein said load bearing element comprises: at least one body integrally formed by additive layer manufacturing (ALM), said body being adapted to provide a controlled heat transfer from said heat generating unit to said heat sensitive supporting structure, said at least one body including an outer conical body with a base of the outer conical body connected to the heat sensitive supporting structure and an apex of the conical body connected to the heat generating unit and an inner conical body with a base of the inner conical body connected to the outer conical body and an apex of the inner conical body connected to the heat sensitive supporting structure, wherein the integrally manufactured body of said load bearing element is a load bearing bracket for attachment of the heat generating unit to said heat sensitive supporting structure being a fuselage of a flying vehicle, wherein said integrally manufactured body of said load bearing element comprises several layers printed from the same or different fire proof materials, and wherein the at least one body comprises a plurality of ventilation holes configured to allow a fluid to enter and to leave internal cavities of the outer conical body and the inner conical body.
2. The combination according to claim 1, wherein the integrally manufactured body of said load bearing element is formed such that the integrally manufactured body is configured to shield the heat sensitive supporting structure from thermal radiation emitted directly or indirectly by said heat generating unit, and/or that the integrally manufactured body is configured to transfer thermal energy received from said heat generating unit by a fluid moving by convection through cooling cavities and/or along cooling ribs of said integrally manufactured body to the surrounding, and/or that the integrally manufactured body is configured to spread the thermal energy received from said heat generating unit by thermal conduction via said integrally manufactured body to a footprint area, where the load bearing element is attached to said heat sensitive supporting structure.
3. The combination according to claim 1, wherein the integrally manufactured body of said load bearing element is formed such that by the controlled heat transfer a mechanical stiffness throughout said integrally manufactured body of said load bearing element and/or a mechanical stiffness of said heat sensitive supporting structure is maintained for a load less than an admissible maximum load, carried by said load bearing element and/or a thermal energy less than a maximum thermal energy generated by said heat generating unit and/or is formed such that the integrally manufactured body at least partially absorbs mechanical forces.
4. The combination according to claim 1, wherein the printed layers of the integrally manufactured body of the load bearing element have different heat transport properties or other physical properties, depending on the position of the respective printed layers relative to the heat generating unit attached by said load bearing element to said heat sensitive supporting structure.
5. The combination according to claim 4, wherein layers of said integrally manufactured body located proximal said heat generating unit comprise at least first thermal conductivity lower than an at least second thermal conductivity of layers located proximal the heat sensitive supporting structure.
6. The combination according to claim 4, wherein layers of the integrally manufactured body proximal said heat generating unit provide an at least first radiation shielding higher than an at least second radiation shielding of layers located proximal the heat sensitive supporting structure.
7. The combination according to claim 1, wherein a cross-section through said integrally manufactured body of said load bearing element parallel to said heat sensitive supporting structure increases towards the heat sensitive supporting structure to spread the thermal energy received from said heat generating unit to an extended footprint area, where the load bearing element is attached to said heat sensitive supporting structure.
8. The combination according to claim 1, wherein the integrally manufactured body of the load bearing element comprises a three-dimensional structure printed by additive layer manufacturing (ALM) according to a three-dimensional bionic design data model read from a database.
9. The combination according to claim 1, wherein the heat generating unit is an auxiliary power unit (APU) mounted in a fire compartment of a flying vehicle or of a land vehicle.
10. A vehicle comprising at least one combination according to claim 1.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
(1) For a more complete understanding of the different aspects of the present invention and the advantages thereof, exemplary embodiments of the invention are explained in more detail in the following description with reference to the accompanying drawings, in which like reference characters designate like parts and in which:
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DETAILED DESCRIPTION
(11) The accompanying drawings are included to provide a further understanding of the different aspects of the present invention and are incorporated in and constitute a part of this specification. The drawings illustrate particular embodiments of the present invention and together with the description do serve to explain the principles underlying the present invention. Other embodiments of the invention and many advantages of the invention will be readily appreciated as they become better understood with reference to the following detailed description. It will be appreciated that common and/or well-understood elements that may be useful or necessary in a commercially feasible embodiment are not necessary depicted in order to facilitate a more abstracted view of the embodiments. The elements of the drawings are not necessarily illustrated to scale relative to each other. It will further be appreciated that certain actions and/or steps in an embodiment of a method may be described or depicted in a particular order of occurrences while those skilled in the art will understand that such specificity with respect to a sequence is not necessarily required. It will also be understood that the terms and expressions used in the present specification have the ordinary meaning as is accorded to such terms and expressions with respect to their corresponding respective areas of inquiry and study, except where specific meanings have otherwise been set forth herein.
(12) With reference to
(13) The load bearing element 1 comprises an APU interface platform 4 fixing the heat generating unit 2 to the load bearing element 1. Further, the load bearing element 1 comprises a flange 5 to connect the load bearing element 1 to the heat sensitive supporting structure 3. The load bearing element 1 further comprises a body 6 integrally formed by additive layer manufacturing, ALM. In a possible embodiment, the APU interface platform 4 and the flange 5 can also form part of the integrally formed body 6. The body 6 is adapted to provide a controlled heat transfer from the heat generating unit 2 to the heat sensitive supporting structure 3.
(14) The body 6 of the load bearing element 1 is formed such that it shields the heat sensitive structure 3 from a thermal radiation emitted directly or indirectly from said heat generating unit 2. In the embodiment shown in
(15) In the shown exemplary embodiment, the body 6 further comprises ventilation holes 9-1, 9-2 in a space between the firewall 7 and the cooling rib 8 as illustrated in
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(18) As can be seen from the exemplary embodiment illustrated in
(19) In the embodiment shown in
(20) In a possible embodiment of the integrally manufactured body 6 of the load bearing element 1, the body is formed such that by controlled heat transfer a mechanical stiffness of the body 6 of the load bearing element 1 and a mechanical stiffness of the heat sensitive supporting structure 3 is maintained at all operation conditions, in particular when a load less than an admissible maximum load is carried by the load bearing element 1 and/or energy less than an admissible maximum thermal energy is generated by the heat generating unit 2. The heat generating unit 2 can be an auxiliary power unit, APU, of an aircraft providing a thermal energy at a temperature T of e.g. 1100? C. at a rate of 116 kW/m.sup.2 in case of failure.
(21) The integrally manufactured body 6 of the load bearing element 1 does comprise several layers which are printed from the same or different fire resistant or fire proof materials. In a possible embodiment, the layers of the body 6 are printed to provide a three-dimensional solid object of a shape corresponding to a digital data model. In a possible embodiment, the body 6 comprises a three-dimensional structure printed by additive layer manufacturing, ALM, according to a three-dimensional bionic design data model read from a database. In a possible embodiment, the manufacturing machine reads the design data model from a database and lays down successive layers of liquid, powder, paper or sheet material to build the body 6 from a series of corresponding cross-sections. These layers correspond to the virtual cross-sections from the data model and are joined or automatically fused to create the final shape of the three-dimensional body 6. In a preferred embodiment, the layers are formed by a fire proof material. The materials can comprise a metal, a metal alloy or thermoplastics. The materials can comprise in particular steel, titanium or inconel. The additive layer manufacturing, ALM, process can be performed by using Fused Deposition Modelling (FDM), electron beam free form fabrication, direct metal laser sintering, selected laser sintering or other additive layer processes. The manufacturing process can comprise a process where layers of powder are consolidated using a laser or electron beam to fuse scans of the slice computer aided design data to create the geometrical form of the body 6. Alternatively, material deposition or extrusion processes can be employed by heating the material through an extrusion nozzle which follows a predefined deposition path to deposit material on top of previous layers to create the three-dimensional geometry of the body 6. For metal, blown powder and wire extrusion can be used, wherein the material can be melted by using a laser or electron beam. In a preferred embodiment, the body 6 of the load bearing element 1 is printed in steel, titanium or inconel. By manufacturing the body 6 by means of additive layer manufacturing, ALM, any desired kind of shape providing the desired heat transfer control can be manufactured wherein an increased complexity of three-dimensional structure of the body 6 does not increase the manufacturing time and effort significantly. By manufacturing the body 6 with additive layer manufacturing, ALM, different functions by a single part can be provided as illustrated in the embodiment shown in
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(26) The form of the integrally manufactured body 6, in particular the number, size and thickness of the branches 19, can be adapted to the respective application and in particular to the amount of thermal energy generated by the heat generating unit 2 and transported through the body 6 to the heat sensitive supporting structure 3.
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(28) In a possible embodiment, the layers 6-i of the integrally manufactured body 6 located close to the heat impacted side in the vicinity of the heat generating unit 2 can provide a higher radiation shielding capability than the layers located close to the heat sensitive supporting structure 3. Accordingly, the layers 6-1, 6-2, 6-3, 6-4, 6-5, 6-6, 6-7 can be printed from different fire resistant materials and can provide different heat transport properties depending on their position within the body 6. The different printed layers 6-i of the integrally manufactured body 6 can also have other differing physical properties, in particular they can have different physical densities. For instance, some layers 6-i can be porous, whereas other layers are solid. Depending on the used material, one or several layers can also have shock-absorbing and/or elastic properties to absorb physical shocks or forces caused by the carried load 2. The materials are preferably fire- and/or heat-resistant materials. For instance, when the heat generating unit 2 comprises a high weight and is accelerated by a flying manoeuvre of a flying vehicle, one or several layers 6-i can be adapted to absorb the resulting mechanical forces due to elastic properties.
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(30) In a possible embodiment, the outer shielding cladding 24 can be formed according to a bionic design data model similar to bone spongiosa. The form of the body 6 of the embodiment shown in
(31) The invention further provides according to a further aspect a method for manufacturing a body of a load bearing element 1, wherein its body 6 is integrally formed by additive layer manufacturing, ALM, such that it provides a controlled heat transfer from a heat generating unit 2 such as an auxiliary power unit APU carried by the load bearing element 1 to a heat sensitive supporting structure 3 to which said heat generating unit 2 is attached. Different ALM technologies can be used including wire-freeform fabrication, extrusion deposition, granular materials binding, lamination, extrusion, fused deposition modelling, direct metal laser melting, electron beam melting and/or selective laser melting.
(32) The load bearing element 1 according to an aspect can comprise one or several bodies formed by additive layer manufacturing, ALM. The load bearing element 1 according to an aspect of the present invention can be used in many applications, in particular for attaching a heat generating unit 2 carried by the load bearing element 1 to a heat sensitive supporting structure 3, e.g. a fuselage or chassis of a vehicle. The load can be carried by the load bearing element 1 or can alternatively be hanging at the load bearing element 1. In a possible embodiment, the body 6 of the load bearing element 1 is formed such that the surface of the heat impacted side is reduced so that the surface of the heat impacted side is shielded from thermal radiation. In a preferred embodiment, the body 6 is formed such that the load path and the path of heat flow are decoupled. In a preferred embodiment, the heat received from the heat generating unit 2 is spread by the body 6 to a wider surface so that the heat sensitive supporting structure 3 can maintain its mechanical stiffness at all operation conditions. The body 6 further provides heat removal, for instance by natural or forced convection. Moreover, the heat removal can be improved by additional cooling ribs and/or cooling tubes. In a possible embodiment, the layers of the body 6 formed by additive layer manufacturing ALM use materials with an adapted heat conduction property to provide a controlled fitting heat transfer. In a possible embodiment, the load bearing element 1 is a bracket for connecting an APU 2 to a fuselage 3 of a flying vehicle, wherein the bracket can be shielded and sealed by a bellow. The APU bracket acts as a heat bridge to the fuselage skin. The load bearing element 1 comprising the integrally manufactured body 6 can act as a heat bridge between the heat generating unit 2 and the heat sensitive supporting structure 2 providing a controlled heat transfer, wherein the cross-section, length, material and arrangement of the manufactured layers 6-i of the body 6 define a temperature on a skin of the heat sensitive supporting structure 3, in particular the fuselage skin of an aircraft fuselage.
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