Patent Description:
It describes a watertight closure mechanism, preferably made of metal material, that clasps the radome around its lower edge with sufficient pressure to guarantee its watertightness, while constituting the receiving surface of the fixing means to the lower base plate to which the radome is attached, without the radome of composite material being machined, or subjected to any operation that could weaken it.

The radome is used to cover an antenna in order to protect it without affecting its electromagnetic properties, while providing good transparency to allow the passage of waves at the same time.

Radomes are made up of solid and light structures capable of withstanding the adverse weather conditions of the environment where they are located and are normally conceived in a mouldable composite material that makes it possible to create curved and/or spherical shapes.

In general, radomes are used to protect antennas installed on ground, sea or air equipment that can be fixed or mobile, such as, for example, submarines. For any application, and for the latter in particular, radomes must meet certain watertightness conditions in their connection to a lower base plate on which they are mounted, which prevent water from entering the radome.

In maritime applications, radomes must withstand pressures of <NUM> bar in the case of ships, or <NUM> bars in the case of submarines, such that the connections between the radome and the lower base plate must be conceived such that the closure that is established between the two elements is watertight at those pressures.

In addition, resistance to temperature changes and a proper shape of the connection between the radome and the base plate are crucial factors to determine the goodness of fit and therefore the durability of the watertight connection.

The lower base plate to which the radome is coupled is usually made of metal material while the radome is made of composite material, due to which a suitable watertight solution is required for a connection that is problematic in principle due to the use of different materials.

A known solution consists in introducing inserts into the lower edge of the radome and defining spaces following the inserts intended to house nuts to which fixing elements are screwed that pass through the lower base plate, ensuring the connection between the base plate and the radome. In order to establish a metal-metal contact in the connection, an L-shaped metal ring is incorporated between the radome and the base, with its horizontal side situated on the edge of the radome and its vertical side situated against the inner face of the radome.

Defining holes to house the inserts in the radome, and the openings intended to house the nuts, weaken the lower surface of the radome, which means that when the radome is subjected to pressure stresses or loads, it leads to deformations resulting in leaks in the watertightness between the ring and the radome, especially between the vertical surface of the ring and the radome.

Another known solution is to laminate the radome so that it incorporates a metal ring to which the lower base plate is affixed in its connection to the radome, a ring that has a pointed tooth that projects upwardly and is clasped by the laminate of the radome. In this case, the problem arises from the different levels of dilation that occur as a result of the use of different materials, which causes a deformation and delamination of this area of the radome leading to a deformation that ultimately allows water to enter.

Furthermore, document <CIT> discloses a radome, a base incorporated underneath the radome and several elements that ensure the sealing of an antenna which is covered inside the radome. The sealing of the antenna inside the radome is get by means of an O-Ring together with a clamp ring which apply pressure against the outer face of the radome and said radome is pressed against the elements of the base, thus facilitating the sealing of the assembly.

Another example is the document <CIT>, where the invention is focused on a sealing frame which includes a female snap ring body molded into the distal edge of a radar collector horn or dish as an integral part thereof. An indented molded slot and a lip form a body, where the slot has a size of diameter less than the body to match in size and shape approximately the inner diameter and width of male compression ring which slaps into place in slot. Male compression ring has a protruding lip which fits into corresponding slot cut or molded into body, to effect a more moisture and weatherproof seal of body, applying pressure from the outside to permit a weatherproof seal.

The radome watertight closure mechanism described in the present invention solves the problem described above by means of an anchoring solution around the radome, which is preferably made of metal, that allows the watertight connection to the lower base plate to which the radome is attached, without the need to machine the composite of the radome. It is, unlike other solutions that weaken the composite of the radome, a closure that simply clasps the radome around its edge with sufficient pressure to guarantee it remains watertight.

The radome watertight closure mechanism essentially comprises:.

Furthermore, in order to join the lower base plate to the connecting base of the closure mechanism, the desired fixing elements will be used, such as, for example, screws that pass through the base plate and thread to the connecting base, without passing through the latter so as not to penetrate the composite of the radome.

The composite of the radome thus remains intact, without drill holes that can result in unwanted deformations. The closure mechanism object of this invention simply clasps the radome by wrapping around its edge, and by means of the pressure exerted by the pressure and closing elements against the radome, optionally through the watertight seal, it guarantees a watertight closure.

The pressure and closing element selected will allow pressure to be exerted on the seal of the radome, which is higher than the external pressure exerted by the environment of the location of the radome, either under the sea, above the sea, in a static or dynamic situation, and/or at high altitudes.

The configuration of the outer ring and the inner ring may vary, as represented in the following drawings, and similarly the radome can show different shapes in the vicinity of its lower edge, which can be vertical on its inner face or, for example, have a sloping heel, contemplating different solutions for mounting the rings around the radome.

To supplement the description that is being made and in order to aid a better understanding of the features of the invention according to a preferred practical exemplary embodiment thereof, a set of drawings has been attached as an integral part of said description, which represent the following by way of illustration and not limitation:.

In light of the figures, a preferred embodiment of the radome watertight closure device constituting the object of this invention is described below.

As shown in <FIG>, the composite radome (<NUM>) has a lower edge (<NUM>), an inner face (<NUM>) and an outer face (<NUM>) that project upwardly from the edge (<NUM>), which is affixed to a lower base plate (<NUM>), normally made of metal material, by means of the closure mechanism object of this invention. This closure mechanism guarantees the watertightness of the radome and constitutes the contact and connection surface with the base plate (<NUM>), to which it will be attached through any fixing means.

As shown in detail in <FIG>, which constitutes an enlarged view of <FIG>, the closure mechanism essentially comprises an outer ring (<NUM>) which partially covers the radome on its outer face (<NUM>), as well as an inner ring (<NUM>) formed by several segments (<NUM>), which have a contact face with a shape similar to that of the inner face (<NUM>) of the radome (<NUM>) against which they rest, and are joined to the outer ring (<NUM>) by corresponding connecting elements (<NUM>), such as screws, so that the outer ring (<NUM>) and the inner ring (<NUM>) clasp the radome (<NUM>) between them.

The closure mechanism also incorporates a connecting base (<NUM>) which is intended to remain against the edge (<NUM>) of the radome (<NUM>), and which in the case of <FIG>, forms part of the outer ring (<NUM>), while in the case of <FIG>, it forms part of the inner ring (<NUM>). In the first case, an upper wing (<NUM>) extends from the connecting base (<NUM>) of the outer ring (<NUM>), which is intended to remain against the outer face (<NUM>) of the radome (<NUM>).

As shown in <FIG>, the inner ring (<NUM>) is formed by several adjoining segments (<NUM>) that are joined to the connecting base (<NUM>) of the outer ring (<NUM>), using the connecting elements (<NUM>) that previously pass through openings (<NUM>) defined in said segments (<NUM>). The segments (<NUM>) press against the radome (<NUM>) by means of a pressure and closing element (<NUM>, <NUM>), in this case a compressive hoop (<NUM>), represented in <FIG> mounted on the inner ring (<NUM>), which ensures the snap-on closure of the segments (<NUM>) of the inner ring (<NUM>) against the inner face (<NUM>) of the radome (<NUM>) and integrally of the outer ring (<NUM>) against the outer face (<NUM>) of the radome (<NUM>).

As shown in <FIG>, the inner ring (<NUM>) has tabs (<NUM>) in its segments (<NUM>) that limit the movement of the compressive hoop (<NUM>), except in the circumferential direction, and said compressive hoop (<NUM>) consists of metal plates (<NUM>) and a first tensioning mechanism (<NUM>) of said metallic plates (<NUM>).

<FIG> shows another solution wherein the radome (<NUM>) does not have a sloping heel in its inner face (<NUM>), but rather the inner face (<NUM>) is straight, and that there is a watertight seal (<NUM>) between the inner ring (<NUM>) and the outer ring (<NUM>).

<FIG> shows that the connecting base (<NUM>) has an extension (<NUM>) that will constitute the surface to which fixing elements (<NUM>), such as those represented in <FIG>, are affixed, which join the lower base plate (<NUM>) to the radome (<NUM>).

The connection solution shown in <FIG> dispenses with the connecting elements (<NUM>) and in this case the inner ring (<NUM>) is a single part that is manufactured such that its outer diameter at <NUM>ºC is greater than the inner diameter of the radome (<NUM>). For placement, the inner ring (<NUM>) is taken to cryogenic temperatures, and after reaching the desired size, the inner ring (<NUM>) is introduced into the radome (<NUM>), where the outer ring (<NUM>) has previously been placed, and the whole system is allowed to reach room temperature. This achieves the required pressure between the rings (<NUM>, <NUM>) and the radome (<NUM>). The outer ring (<NUM>) can be co-laminated in the manufacturing process of the radome (<NUM>) itself, or glued or even machined with its inner diameter, which is smaller than the outer diameter of the radome (<NUM>), and then introduced by heating the outer ring (<NUM>).

<FIG> and <FIG> reproduce the same closure mechanism as <FIG>, showing, unlike <FIG>, that in <FIG> the inner ring (<NUM>) is formed by several segments (<NUM>), and that in <FIG>, the radome incorporates a heel. Both <FIG> and <FIG> show the connecting elements (<NUM>) as well.

<FIG> shows a solution similar to <FIG>, representing a larger number of segments (<NUM>) and tabs (<NUM>).

<FIG> shows an alternative to the use of tension hoops (<NUM>), wherein the pressure and closing element (<NUM>, <NUM>) now consists of a second tension mechanism (<NUM>) which is a spacer mechanism (<NUM>) that joins and expands the segments (<NUM>) in the circumferential direction, exerting snap-on or compressive pressure on the radome (<NUM>). This spacer mechanism (<NUM>) may consist of mechanical wedges or cams, or hydraulic systems, for example.

<FIG> shows that the closure mechanism incorporates two pressure and closing elements (<NUM>, <NUM>) consisting of corresponding compressive hoops (<NUM>) situated at different heights.

Claim 1:
A radome watertight closure mechanism, wherein the radome (<NUM>) is made of composite material and has a lower edge (<NUM>), an inner face (<NUM>) and an outer face (<NUM>) that project upwardly from the edge (<NUM>), wherein said radome is intended to be affixed to a lower base plate (<NUM>), normally made of metal material, by means of corresponding fixing elements (<NUM>), characterised in that the closure mechanism comprises:
- an outer ring (<NUM>) intended to remain at least against the outer face (<NUM>) of the radome in the vicinity of the lower edge (<NUM>) of the radome;
- an inner ring (<NUM>) formed by one or more adjoining segments (<NUM>), intended to remain against the inner face (<NUM>) of the radome in the vicinity of its lower edge (<NUM>), and joined to the outer ring (<NUM>), such that the inner ring (<NUM>) and the outer ring (<NUM>) clasp the radome around its lower edge (<NUM>) between them;
- a connecting base (<NUM>) intended to be placed against the edge (<NUM>) of the radome, which may form part of the outer ring (<NUM>) or the inner ring (<NUM>) and constitutes the contact surface with the base plate (<NUM>); and
- at least one pressure and closing element (<NUM>, <NUM>) which applies pressure to the inner ring (<NUM>) such that the inner ring (<NUM>) applies compressive pressure from the inside of the radome (<NUM>) against the inner face (<NUM>) of the radome (<NUM>) for assuring the closure of the inner ring (<NUM>) and the outer ring (<NUM>) against the radome (<NUM>).