Abstract:
A vehicle fairing including an electrical routing for conducting power and/or control signals between spaced-apart components of a vehicle structure. The vehicle fairing includes an outer surface configured to form part of an outer surface of a vehicle body. The electrical routing includes a printed circuit board having a substrate and a first conductive path for conduction of electrical current or signals provided on the substrate. The substrate is substantially rigid and forms at least a portion of the outer surface of the vehicle fairing.

Description:
RELATED APPLICATION 
       [0001]    This application claims priority to Great Britain patent application GB 1513267.3 filed on Jul. 28, 2015, the entirety of which is incorporated by reference. 
       FIELD 
       [0002]    The present invention relates to a vehicle fairing including an electrical routing. 
       BACKGROUND 
       [0003]    Aircraft comprise complex wiring systems for the transmission of power and control signals between the various components and systems of the aircraft. Conventionally, these electrical components/systems are connected by cables routed through the aircraft structure. These cables are conventionally fastened within cable raceways, which are elongate metallic ducts comprising one or more channels in which the cables are retained. The raceways serve the purpose of guiding and securing the cables, protecting the cables from mechanical damage and also protecting them from electro-magnetic hazards (EMH), which include various electrical interferences and threats such as electromagnetic interference (EMI), electromagnetic coupling (EMC) and radio frequency interference (RFI). 
         [0004]    The cables may also be provided as an over-braided cable harness, which comprises a bundle of cables within a protective sleeve, of a material such as Nome™, Kevlar™, nylon or other suitable material, and an outer braided metallic mesh. This provides the cables with both mechanical and electrical/EMH protection. The cable harness may then be secured by clips that retain the harness to the aircraft structure or within a raceway. 
         [0005]    Such cable harnesses for the transmission of power and signals comprise a large number of components and a high weight of materials and also occupy a large volume of space on or within the vehicle structure. For example, the electrical raceways require mechanical fastening to the vehicle structure, the cables must be fastened within the raceway by clips or other suitable fasteners, and a minimum spacing must be provided between the harness and any conductive (e.g. metallic) structure to which the harness is attached, to reduce the risk of electrical arcing between the harness and the conductive structure should a cable become fretted and the conductive inner wire exposed. The complexity of these cable arrangements also results in a long installation time in the vehicle construction process, and a complex installation process. 
         [0006]    In certain areas of an aircraft, cables must be routed externally, such as on the wings where fuel tanks are located. Here, since cables may not pass through the fuel tanks for safety reasons, yet power is required for the fuel pumps within the tanks, the power cables must be provided on the underside of the wing, and then covered with a fairing for environmental protection of the cables and aerodynamic performance of the wing. Again, this is a complex arrangement with long installation time as part of the aircraft construction process, and also results a number of relatively large additional fairing structures being disposed on the underside of the wing, reducing aerodynamic performance. 
         [0007]    It is desirable to provide a vehicle fairing and electrical routing that substantially alleviates or overcomes one or more of the disadvantages mentioned above. 
       SUMMARY 
       [0008]    According to an embodiment of the invention, there is provided a vehicle fairing comprising an electrical routing for conducting power and/or control signals between spaced-apart components of a vehicle structure, the vehicle fairing comprising an outer surface configured to form part of an outer surface of a vehicle body, the electrical routing comprising a printed circuit board having a substrate and a first conductive path for conduction of electrical current or signals provided on the substrate, wherein the substrate is substantially rigid and forms at least a portion of the outer surface of the vehicle fairing 
         [0009]    The printed circuit board may comprise a multi-layer printed circuit board having a plurality of layers of substrate. The first conductive path may be provided on a first layer of substrate and a second conductive path may be provided on a second layer of substrate, the second conductive path being electrically insulated from the first conductive path. 
         [0010]    The second conductive path may be configured to serve as a current return path. 
         [0011]    The substrate may be substantially rigid and the electrical routing may comprise a unitary assembly with a protected conductive layer. 
         [0012]    The or each conductive layer may be sandwiched between layers of substrate such that the or each conductive layer is embedded within the body of the vehicle fairing. 
         [0013]    The printed circuit board substrate(s) may comprise polyether ether ketone (PEEK), polyether ketone ketone (PEKK) or Glass Fibre Reinforced Plastic (GFRP). 
         [0014]    The printed circuit board may comprise at least one mounting lug integrally formed with the substrate for securing the printed circuit board to a vehicle structure. 
         [0015]    The substrate may form the entire outer surface of the vehicle fairing. 
         [0016]    The vehicle fairing may comprise an aircraft wing fairing. 
         [0017]    The vehicle fairing may be configured to be positioned on the outer underside of an aircraft wing and to connect a fuel pump within the aircraft wing to a supply of electrical power running along an external surface of the aircraft wing. 
         [0018]    The present invention also provides an aircraft structure including an electrical component and, a vehicle fairing as described above connected to the aircraft structure, wherein the electrical routing may be connected to the electrical component for conveying power and/or control signals thereto. 
         [0019]    The aircraft structure may comprise a current return network, and the second conductive path may be electrically connected to the current return network. 
         [0020]    The printed circuit board may comprise a lead with a connector for electrically connecting the printed circuit board to an electrical system of the aircraft. 
         [0021]    The lead may be flexible and may include a non-conductive protective sleeve and an electrically conductive metallic outer braiding. 
         [0022]    The aircraft structure may comprise an aircraft wing. 
         [0023]    The aircraft wing may comprise a fuel tank, and the electrical component may comprise a fuel pump within the fuel tank, and the electrical routing may be connected to the fuel pump. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0024]    Embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: 
           [0025]      FIG. 1  shows a conventional cable routing used in an aircraft; 
           [0026]      FIG. 2  shows a schematic underside view of one side of a conventional aircraft wing and fuselage; 
           [0027]      FIG. 3  shows a schematic cross-sectional view of a conventional aircraft wing along the line X-X of  FIG. 2 ; 
           [0028]      FIG. 4  shows a printed circuit board electrical routing for use in a vehicle fairing of a first embodiment of the invention; 
           [0029]      FIG. 5  shows a vehicle fairing of a second embodiment of the invention comprising a printed circuit board electrical routing, with a portion shown as an enlarged cut-away view; 
           [0030]      FIG. 6  shows a schematic underside view of one side of an aircraft wing and fuselage incorporating the fairing of  FIG. 5 ; and 
           [0031]      FIG. 7  shows a cross-sectional view along the line Y-Y of the aircraft wing of  FIG. 6 . 
       
    
    
     DETAILED DESCRIPTION 
       [0032]    Referring now to  FIG. 1 , a conventional cable routing  1  as used in aircraft, such as commercial airliners, is shown and includes a cable raceway  2  comprising an elongate channel, usually metallic such as aluminium, with mounting lugs  3  for the raceway  2  to be secured to an aircraft structure, such as a fuselage or wing. Within the raceway  2  are cable harnesses  4  (for simplicity, only one is shown in  FIG. 1  although usually multiple harnesses would be provided within a raceway). Each harness  4  comprises a bundle of cables  5 , each with an insulating outer layer  6 , and the bundle is retained within a protective sleeve  7 . The sleeve  7  is provided with a metallic over-braiding  8  for electrical and EMH protection of the cables  5  within the harness  4 . Each cable harness  4  is fastened to the raceway  2  by a plurality of mounting clips  9 . In an alternative conventional configuration, cable bundles may be routed in individual channels within a single raceway structure, and in such a configuration, the cables may not have additional sleeve protection for abrasion or EMI/EMH protection as this is performed by the separating channel walls of the raceway. 
         [0033]    It will be appreciated from the above that the cable routing  1  comprises a large number of components and is relatively complex in construction. This increases the cost of the cable routing  1  and it occupies a large volume of space within the aircraft structure and is time consuming to install. Furthermore, if any of the mounting clips  9  fail, the individual cable harnesses  4  within the raceway  2  may move around, resulting in wear of the cable harness  4  and potentially a short-circuit. 
         [0034]      FIG. 2  shows an underside view of one side of a conventional aircraft fuselage and wing  10 , and  FIG. 3  shows a cross-section through the wing  10  of  FIG. 2  along the line X-X. The wing  10  includes a fuel tank  11  with a fuel pump  12  disposed within the tank. For efficiency of space, in conventional aircraft wing design, an upper surface  13  and a lower surface  14  of the wing  10  comprise upper and lower walls of the fuel tank  11 , respectively. Similarly, a leading edge spar  15  and a trailing edge spar  16  respectively comprise front and rear walls of the fuel tank  11 . The wing  10  further comprises a leading edge  17  ahead of the leading edge spar  15  and a trailing edge  18  behind the trailing edge spar  16 . 
         [0035]    For safety reasons, electrical cables may not be routed through fuel tanks. Therefore, to provide electrical power to the fuel pump  12 , a cable routing  1  must pass from a connection to the fuel pump  12  on the lower surface  14  of the wing  10 , along the outside of the lower surface  14  of the wing  10  to proximate the trailing edge spar  16  where a power routing (not shown) to which it is to be connected, is located. As such, a fairing  19  is provided on the lower surface  14  of the wing  10  to cover the cable routing  1  to protect it from environmental elements, and to ensure the wing  10  is aerodynamic. 
         [0036]      FIG. 2  shows locations  20  of fairings  19  in a conventional aircraft wing  10  and shows that a number of such fairings  19  are needed to cover all the required cable routings  1 . Given the size of the cable routings  1  and therefore the required size of the fairings  20 , this results in additional aerodynamic drag on the wing  10  and complexity of construction/installation. 
         [0037]      FIG. 4  shows an electrical routing  101  which may be incorporated in a vehicle fairing  100  of a first embodiment of the invention. The electrical routing  101  comprises an elongate printed circuit board (PCB) comprising a first substrate layer  102 , a plurality of conductive tracks  103  on the first substrate layer  102 , and a second substrate layer  104  sandwiching the conductive tracks  103  between it and the first substrate layer  102 . A plurality of conductive tracks  103  are also provided on the second substrate layer  104  and a third substrate layer  105  is provided over these conductive tracks  103  on the second substrate layer  104 . 
         [0038]    The substrate layers  102 ,  104 ,  105  are substantially rigid and are made of a material which has good structural strength and impact resistance, and may be made of polyether ether ketone (PEEK) or polyether ketone ketone (PEKK), Glass Fibre Reinforced Plastic (GFRP) or other suitable material. The PCB electrical routing  101  is formed as part of a vehicle fairing  100 . The vehicle fairing  100  is formed by fairing panels  100   a  disposed adjacent to the PCB electrical routing  101  and connected thereto, to form the overall vehicle fairing  100 . The fairing panels  100   a  may be bonded to the PCB electrical routing  101 , or may be moulded therewith, or co-cured or co-bonded therewith. 
         [0039]    The vehicle fairing  100  includes an outer surface  100   a  which, in use, forms part of the outer surface of a vehicle to which the vehicle fairing  100  is attached or incorporated. The first substrate layer  102  includes a surface  102   a  that forms part of the outer surface  100   a  of the vehicle fairing  100 . 
         [0040]    The PCB may include one or more projecting lugs  108  integrally formed with one of the substrate layers  102 ,  104 ,  105  to enable the vehicle fairing  100  with incorporated PCB electrical routing  101  to be secured to a vehicle structure. Alternatively, the PCB may include a plurality of slots, keyways, holes or other recess features integrally formed with one of the substrate layers  102 ,  104 ,  105  to enable the fairing  100  with incorporated PCB electrical routing  101  to be secured to a vehicle structure by a projecting connector from the vehicle structure. 
         [0041]    In use of the vehicle fairing  100  in a vehicle, the PCB electrical routing  101  replaces a conventional electrical routing  1  and the overlying fairing  19 , with the various power and/or control signals that would conventionally be conducted through cables  5  of a cable harness  4  instead being conducted through the various conductive tracks  103  of the PCB. The PCB electrical routing  101  of the fairing  100  of the invention is much simpler and therefore quicker to install than a conventional cable routing, as it only required the PCB to be mounted to the vehicle structure as part of the fairing thereof, and does not include multiple different components and fixings. The PCB electrical routing  101  of the fairing  100  of the invention is also lighter and smaller than a conventional electrical routing  1 , and so occupies less space on or within a vehicle structure. It is an important property of the PCB electrical routing  101  that it is a rigid assembly where the conductors within it are protected from damage. 
         [0042]    The PCB electrical routing  101  of the invention may be connectable to a current return network of the vehicle in which it is installed. As such, one of the conductive layers  103  may be a dedicated conductive element for connection to the vehicle current return network. Such an electrical routing  101  would preferably therefore comprise a multi-layer PCB (as shown in  FIG. 4 ) in which the signal/power conductive tracks  103  are electrically isolated (by being provided on a different substrate layer  102 ,  104 ,  105 ) from the layer of conductive track  103  providing the current return system functionality. The electrical routing  101  may include an exposed section  106  of the conductive track  103  that provides the current return function, in order to be securely electrically bonded to the vehicle current return network. Alternatively, the electrical routing  101  may include an electrical bonding breakout  107  (also shown in  FIG. 4  for completeness) for connection to the vehicle current return network. 
         [0043]    The PCB of the electrical routing  101  preferably comprises multiple substrate layers  102 ,  104 ,  105 , and may include additional outer substrate layers, and/or thicker outer substrate layers, such that the electrical routing  101  has the required structural rigidity and damage tolerance whilst allowing for structural deflections of the vehicle in which it and the vehicle fairing  100  is installed. 
         [0044]      FIG. 5  shows a vehicle fairing  200  a second embodiment of the invention comprising an electrical routing  201 . As with the first embodiment, the electrical routing  201  comprises an elongate printed circuit board (PCB) comprising a first, second and third substrate layers  202 ,  204 ,  205  and a plurality of conductive tracks  203 . However, one difference of the vehicle fairing  200  of the second embodiment is that the PCB electrical routing comprises the entire vehicle fairing component  200 . The outer layer  202  of PCB substrate forms an outer wetted surface  200   b  of the vehicle fairing  200  of the vehicle to which it is secured. The exemplary vehicle fairing  200  shown in  FIG. 5  comprises a fuel pump fairing for fitment to the underside of an aircraft wing  10 , as shown in  FIGS. 6 and 7 . 
         [0045]    The electrical routing  201  shown in  FIG. 5  includes flexible, electrically and mechanically protected leads  208 . A first end of each lead  208  is electrically connected to the conductive tracks  203  of the electrical routing  201  and an opposite end of each lead  208  is provided with an electrical connector  209 —one for connection to a mating connector of a fuel pump  12  accessible on the lower surface  14  of the aircraft wing  10 , and one for connection to the aircraft&#39;s power and/or control system (not shown). In an alternative embodiment of electrical routing  201  (not shown), the leads  208  may be omitted and instead the electrical routing  201  may include integrated electrical connectors directly connected to the conductive tracks  203  of the PCB and which connect directly into the components of the vehicle to which the electrical routing is to be coupled, such as the fuel pump  12  of the aircraft wing and electrical/control system of the aircraft. 
         [0046]    In use, the vehicle fairing  200  of the second embodiment replaces both a conventional electrical routing  1  and the overlying fairing  19  on the lower surface  14  of the aircraft wing  10 , with the various power and/or control signals that would conventionally be conducted through cables  5  of a cable harness  4  instead being conducted through the various conductive tracks  203  of the PCB. This thereby significantly reduces the total number and weight of parts required for the vehicle. Also, the PCB is shaped and profiled in an aerodynamic form such that airflow disturbance and aerodynamic drag are minimised when the vehicle fairing  200  is fitted to the wing  10 , with the outer-most substrate layer  202  of the PCB  201  forming the outer wetted surface  200   b  of the aircraft wing. The combined and integrated component of the fairing  200 /electrical routing  201  of the second embodiment of the invention is therefore much simpler and therefore quicker to install than a conventional cable routing, as it only requires the PCB to be mounted to the vehicle structure, and does not include multiple different components and fixings, and negates the need for any additional overlying fairing. The fairing  200 /electrical routing  201  of the second embodiment of the invention is also lighter and smaller, and so, as can be seen from  FIG. 7 , protrudes much less from the lower surface  14  of the aircraft wing  10  than a conventional cable routing  1  and fairing  19  arrangement, significantly reducing aerodynamic drag. 
         [0047]    An advantage of the fairings  100 ,  200  of the present invention is that they can be manufactured more quickly and simply than known types of vehicle components with integrated electrical routings. For example, it is known to produce vehicle structures with embedded wires, which are sometimes known as “wires in composites”. Here, conventional electrical routings are embedded into composite components in a multi-stage manufacturing process. However, by forming the PCB electrical routing as part of the external structure of the vehicle fairing, and particularly forming the entire vehicle fairing from the PCB substrate(s), the number of manufacturing steps is reduced, and so cost and time of manufacture is reduced. In particular, a time and energy-consuming autoclave procedure is not required in manufacturing the vehicle fairing of the invention. 
         [0048]    The PCB vehicle fairing may be shaped, profiled and packaged to match the vehicle structure shape and space available. The PCB vehicle fairing preferably has a cross-section and profile shape that minimises air flow disturbance and results in minimal aerodynamic drag. 
         [0049]    Although the electrical routing of the first embodiment of the invention is shown as having three substrate layers  102 ,  104 ,  105 , the invention is not limited to this configuration and an electrical PCB routing of the invention may have a single layer of substrate with a single layer of conductive tracks, or may comprise any number of multiple layers of substrate with multiple layers of conductive tracks. 
         [0050]    It will be appreciated from the description above and exemplary embodiments that within the present inventive concept, the PCB electrical routing  101 ,  201  may comprise a portion of the outer surface  100   b  of the vehicle fairing  100 , or may comprise the entire outer surface  200   b  of the vehicle fairing  200 . Also, although described above in the context of an aircraft fairing, the invention is not intended to be limited to such fairings and may comprise fairings used for any other type of vehicle, such as cars, trucks, boats, trains, etc. 
         [0051]    While at least one exemplary embodiment of the present invention(s) is disclosed herein, it should be understood that modifications, substitutions and alternatives may be apparent to one of ordinary skill in the art and can be made without departing from the scope of this disclosure. This disclosure is intended to cover any adaptations or variations of the exemplary embodiment(s). In addition, in this disclosure, the terms “comprise” or “comprising” do not exclude other elements or steps, the terms “a” or “one” do not exclude a plural number, and the term “or” means either or both. Furthermore, characteristics or steps which have been described may also be used in combination with other characteristics or steps and in any order unless the disclosure or context suggests otherwise. This disclosure hereby incorporates by reference the complete disclosure of any patent or application from which it claims benefit or priority.