HOUSING SYSTEM FOR AIRCRAFT MOUNTED COMPONENTS

A traffic collision avoidance system (TCAS) device Configured to reduce or prevent the infiltration of water and other environmental contaminants into the interior of the TCAS device. The device having a radome attached to the ground plane so that the interior surface of the radome and the inner surface of the ground plane form an inner chamber. The inner surface of the ground plane has a PCB channel wall defining a center well facing the inner chamber and configured to receive a printed circuit board (PCB).

FIELD

The present disclosure relates generally to a housing for mounting components to an exterior of an aircraft, and in particular to a housing system for traffic collision avoidance system (TCAS) type devices.

BACKGROUND

Aircraft have various externally-mounted systems. For example, various communication, aviation location and aircraft avoidance systems are utilized in aircraft. These systems may utilize antenna systems in a housing so as to protect the antenna systems from environmental hazards such as wind and water.

For example, one such system is a traffic collision avoidance) system (TCAS). In areas of congested airspace or low visibility, it is desirable for a pilot of one aircraft to be warned of the presence of a nearby aircraft so the respective aircraft may maneuver the aircraft to avoid collision. A traffic collision avoidance system (TCAS) employs a transponder mounted on the aircraft that communicates with transponders on nearby aircraft. In this way, the aircraft control systems automatically communicate and provide the pilots with appropriate and timely information about nearby aircraft.

TCAS devices are typically mounted on the external surface of the aircraft. For example, a commercial aircraft may have two TCAS devices, one mounted on the underside of the aircraft and one mounted on the top side in an area adjacent to the cockpit. The TCAS device has three major components, a ground plane, a radome, and an antenna assembly. Bonding material can be applied about the periphery of the ground plane to couple the radome to the ground plane and seal the antenna assembly from the external environment.

Since the TCAS devices are mounted on the outside of the aircraft, the devices need to operate over a wide environmental temperature range, typically on the order of −67° F. to 158° F. (−55 C to 70 C). This wide range of operating temperatures places a great deal of stress on the components of the TCAS device. In particular, the bonding layer between the ground plane and the radome is subjected to stresses due to the disparity between the coefficients of thermal expansion of the chassis and the radome. Repeated thermal cycling of the TCAS device may then result in a breach in the bonding layer allowing water, rain, de-icing fluids, and other fluids to migrate into the interior portion of the TCAS device. The entry of the condensation may then result in corrosion of the ground plane and antenna assembly, or generally result in malfunction of the antenna assembly.

While existing TCAS devices are suitable for their intended purposes, there remains a need for improvements. In particular, there remains a need for improvements in reducing or preventing the infiltration of water and other environmental contaminants into the interior of the TCAS device.

SUMMARY

This disclosure relates generally to a housing for mounting components to the exterior of an aircraft. Generally, the housing comprises a radome and a ground plane. The radome having an interior surface and an exterior surface, and ground plane having an inner surface and an outer surface. The radome is attached to the ground plane so that the interior surface of the radome and the inner surface of the ground plane form an inner chamber. The inner surface of the ground plane has a PCB channel wall defining a center well facing the inner chamber and configured to receive a printed circuit board (PCB). The PCB channel wall blocks flow of liquids (water, de-icing fluids, and similar fluids) along the inner surface of the ground plane so as to prevent such liquids and/or fluids from entering the center well. Typically, the PCB channel wall is continuous around the center well. Additionally, the ground plane can further comprise a plurality of additional channel walls, which along with the PCB channel wall form a plurality of channels on the inner surface to direct flow of liquids and/or fluids along the inner surface of the ground plane.

In a more specific embodiment, the disclosure relates to a traffic collision avoidance system (TCAS) device. The device comprising a housing, an antenna assembly and at least one connector.

In this TCAS device, the housing is generally as described above. In this embodiment as well as others, the ground plane can additionally define at least one aperture within the center well. The aperture extending from the inner surface to the outer surface.

The antenna assembly is contained within the inner chamber of the housing, and has at least one antenna, a printed circuit board operatively connected to the antenna. The printed circuit board is positioned in the center well. The connector is positioned within at least one aperture so that the connectors can transmit hard-wired signals between the antenna assembly within the housing and outside the housing.

DETAILED DISCLOSURE

Numerous specific details are set forth in order to provide a thorough understanding of the embodiments described herein. However, those of ordinary skill in the art will understand that the embodiments described herein can be practiced without these specific details. In other instances, methods, procedures and components have not been described in detail so as not to obscure the related relevant feature being described.

This disclosure is directed generally to a housing for mounting components to the exterior of an aircraft. Such housings are used for a variety of purposes but generally for ones where an apparatus needs to be outside any shielding of electromagnetic radiation provided by the body of the aircraft but needs protection from the elements such as provided by a radome structure. A radome being a weatherproof enclosure that protects an electromagnetic antenna. The radome is constructed of material transparent to electromagnetic waves at least at electromagnetic frequencies used by the antenna. While generally described in terms of a traffic collision avoidance system (TCAS) used on aircrafts, the housing may be used with a wide variety of electromagnetic antenna systems such as a wide-angle augmentation system (WAAS), a European geostationary navigation overlay service (EGNOS), a multi-functional satellite augmentation system (MSAS), or other type of navigation augmentation system for aircraft.

As illustrated inFIG.1, these systems are typically mounted on the exterior of an aircraft. In the illustrated embodiment, the device12may be installed on an aircraft10at one or more locations such as on the top or the bottom of the fuselage of the aircraft10or other areas that are not shielded from radar interrogation.

Turning now toFIG.2, an exemplary TCAS device is shown in exploded view. The illustrated TCAS device incorporates features of the present disclosure. The TCAS device20includes a radome22mounted or attached to a ground plane30. As indicated above radome22is constructed of material transparent to electromagnetic waves at least at electromagnetic frequencies used by the antenna. For example, radome22may be made from polymer materials such as polyethersulfone (PES) cover layer with urethane foam body. Radome22has an exterior surface24and an interior surface26(seeFIG.3.)

Generally, ground plane30(sometimes referred to as a chassis or a plate) is made of a conductive material so as to perform the grounding function. For example, the ground plane30can be made from an aircraft grade aluminum alloy, such as 6061 for example. Ground plane30has an outer surface32(seeFIG.9) and inner surface34.

Radome22can be attached to ground plane30by any suitable means such as rivets or bolts36. Conventionally, a bonding material can be applied about the periphery of the ground plane30to couple the radome22to the ground plane30and seal the antenna assembly from the external environment. For the current device, such bonding serves as a primary means of preventing liquids (including moisture/water, de-icing fluids, and similar fluids) from entering the housing and adversely affecting the components of the device; however, as discussed above, over time this primary means can develop leaks allowing liquids into the housing.

When radome22is mounted on ground plane30, interior surface26of radome22and inner surface34of ground plane30form an interior chamber, shown roughly as area38in the exploded view ofFIG.2; though when radome22is mounted on ground plane30, chamber38is completely enclosed by the interior surface26and inner surface34.

An antenna assembly40is positioned within chamber38. Antenna assembly40typically includes a printed circuit board (PCB)42and one or more antenna44that are separated from PCB42by standoffs46. PCB42is located on ground plane30, as further described below. The mounting can be by bonding, mounting screws or other suitable securing means.

Additionally, when device20is attached to an aircraft, a gasket28can be utilized between ground plane30and the aircraft surface.

Turning now toFIGS.5-9, the features of a ground plane30according to this disclosure can be better understood. The inner surface34of the ground plane has a PCB channel wall50defining a center well52facing the interior chamber38and configured to receive a printed circuit board (PCB). The PCB channel wall50is designed to block the flow of liquids traveling along inner surface34of ground plane30so as to prevent liquid from entering the center well and potentially adversely affecting PCB42. Typically, PCB channel wall50is continuous around center well52. Additionally, as illustrated, the housing can further comprise a plurality of additional channel walls54, which along with the PCB channel wall50form a plurality of channels56on the inner surface to direct flow of liquids along the inner surface34of the ground plane30. Additionally, ground plane30can define at least one aperture64within center well52. The aperture64extending from the inner surface34to the outer surface32.

As will be realized the thickness of ground plane30at the center well52and at channels56will be less than that at PCB channel wall50and additional channel wall54. For example, ground plane30at center well52can have a well thickness60. The wall thickness62of ground plane30at PCB channel wall50and additional channel walls54generally will be at least 125%, 150% or 200% of well thickness60, and generally will be at most 400%, 300% or 250% of well thickness60. The PCB channel wall50and each additional channel wall54does not have to have the same wall thickness62, though they can. Also, while the thickness at the center well52will generally be the same or about the same as at channels56, they can be different but typically each will be in the range relative to the wall thickness indicated above for the well thickness and wall thickness.

As further illustrated byFIGS.10and11, PCB42is mated into center well52and is connected to at least one terminal or connector66. Each such connector66can be positioned in a respective aperture64so that the connectors can transmit hard-wired signals between the antenna assembly40within the housing and outside the housing. More specifically, there are typically a plurality of terminals or connectors66, which are coupled to the PCB42opposite the antenna44. The connectors66pass through apertures64. Connectors66couple with conductors (not shown) in the aircraft to transmit signals between antenna assembly40and the aircraft's control systems (not shown).

Therefore, the present systems and methods are well adapted to attain the ends and advantages mentioned, as well as those that are inherent therein. The systems and methods may be modified and practiced in different but equivalent manners apparent to those skilled in the art having the benefit of the teachings herein. Furthermore, no limitations are intended to be the details of construction or design herein shown, other than as described in the claims below. It is therefore evident that the particular illustrative examples disclosed above may be altered or modified, and all such variations are considered within the scope and spirit of the present treatment additives and methods. While the systems and method are described in terms of “comprising,” “containing,” “having,” or “including” various components or steps, the systems and methods can also, in some examples, “consist essentially of” or “consist of” the various components and steps. Whenever a numerical range with a lower limit and an upper limit is disclosed, any number and any included range falling within the range are specifically disclosed. In particular, every range of values (of the form, “from about a to about b,” or, equivalently, “from approximately a to b,” or, equivalently, “from approximately a-b”) disclosed herein is to be understood to set forth every number and range encompassed within the broader range of values. Also, the terms in the claims have their plain, ordinary meaning unless otherwise explicitly and clearly defined by the patentee.