Patent application title: Spaced transparent armor for a motorized vehicle
David E. Hubert (Natrona Heights, PA, US)
IPC8 Class: AF41H702FI
Class name: Shields transportable self-propelled, e.g., tanks, etc.)
Publication date: 2012-07-19
Patent application number: 20120180638
Transparent armor for a vehicle, featuring a sealed gap or space between
two transparent armor components (10a 10ba), the gap or space created by
positioning spacer material (12) between the components, and holding the
components on the spacer material using a seal adhesive (16) serving as
both a structural adhesive (for holding the armor components on the
spacer material and so in a constant spaced apart relation) and a seal
(for preventing air from entering the gap or space.
1. Transparent armor for use as a window of a vehicle, comprising: a
vehicle window frame (24); a stack of three or more components (10a 10b)
disposed within the vehicle window frame (24), each component consisting
of three or more layers of transparent materials having nominal
thicknesses of 8 mm and separated from each other by inter-layers of PVB
or urethane nominally 1 mm thick, each component provided as a rigid
laminate using an autoclave operation so as to cause the inter-layers to
adhere the layers together, the components (10a 10b) separated from each
other by spacer material (12) so that adjacent components are held apart
by a respective gap or space of at least 3 mm; and a seal adhesive (16)
disposed so as to cover the edges of the stack of three or more
components (10a 10b) and hold the stack together; wherein the seal
adhesive (16) is selected from the group consisting of adhesives applied
in the form of a liquid and a structural adhesive tape.
6. Transparent armor as in claim 1, further comprising at least one tube (20) leading from the gap or space through the seal adhesive (16) to a point of exit from the seal adhesive (16) exposed to ambient air.
7. Transparent armor as in claim 1, further comprising hydrophobic coatings (15) on surfaces of the components (10a 10b) forming walls of the gap or space.
CROSS REFERENCE TO RELATED APPLICATION
 Reference is made to and priority claimed from U.S. provisional application Ser. No. 61/201,457 filed Dec. 11, 2008.
FIELD OF THE INVENTION
 The present invention pertains to the field of armor for motorized vehicles. More particularly, the present invention pertains to the field of spaced transparent armor used on vehicles for military or security force applications.
BACKGROUND OF THE INVENTION
 Vehicles used by the military or other security forces require armor to protect occupants from ballistic impacts, such as impacts by bullets, flying fragments, bomb fragments and bomb shock waves. Such armor may be opaque or transparent, with the latter serving as windows, often called transparent armor and sometimes called bullet-proof windows.
 Such vehicular transparent armor is typically formed as a so-called lamination of a stack of layers of ballistic materials separated by so-called inter-layers of a PVC (poly-vinyl chloride) or urethane. The ballistic materials and inter-layers are assembled in a (loose) stack, and put into an autoclave (a chamber in which the temperature and pressure are kept to higher than ambient levels for a period of time), which causes the PVC and/or urethane inter-layers to conform to and adhere to the adjacent surfaces of ballistic materials, resulting in a rigid, transparent stack of the ballistic materials, often called a lamination of ballistic materials.
 Such single-lamination vehicular transparent armor is typically much heavier than opaque armor per square foot of the same level of protection. Further, when such transparent armor stops a threat (e.g. stops a bullet), it can crack over so great an area as to no longer be useable as a window.
 In the case of opaque armor, it is known that sometimes so-called spaced armor--panels of opaque armor components (each of which may be an assembly of various layers of different ballistic materials) held in spaced apart relation--is more effective, per unit weight, than a single panel of opaque armor. In the case of transparent armor for architectural applications, spaced transparent armor components--each typically a lamination of the same or different transparent ballistic materials separated from adjacent laminations by a gap or space--are used in order to provide insulation, and it is known that such transparent armor can be lighter, for the same protection, than a single-lamination (or single ballistic material, i.e. monolithic) transparent armor. However, the mechanical construction used in providing architectural spaced transparent armor cannot stand up to the forces of vibration and other forces encountered during vehicle operation, and so such constructions cannot be used as vehicular transparent armor. Even if such a transparent armor system could hold together, there is a high risk of moisture-bearing air getting into the gap or space between laminations.
 Thus what is needed is spaced transparent armor suitable for use as windows on vehicles, i.e. spaced transparent armor that resists damage caused by forces of vibration and other forces likely to be experienced during vehicular operation.
 The invention provides a spaced transparent armor suitable for use in a vehicle, comprising two or more transparent armor components, each of which may be a different lamination of various ballistic materials or a single ballistic material, with each adjacent pair held in spaced apart relation by spacer material disposed along the periphery of and between the pair of armor components so as to form a gap or space between the pair, with all the armor components and all the spacer material held together by a seal adhesive, thereby keeping each gap or space sealed off from ambient air.
DESCRIPTION OF THE DRAWINGS
 FIG. 1 is a cross-sectional view of spaced transparent armor according to an embodiment of the invention, shown mounted in a vehicle window frame and lying on the side of the armor that would be mounted in a vehicle facing into the vehicle, with a vertical sectional cut taken through the mounting frame and armor, the armor having a sealed gap or space between two armor components created using spacer material and a seal adhesive applied so as to hold together the armor components and the spacer material, and to hold the assembly on the vehicle window frame.
 FIG. 2 is a cross-sectional view of spaced transparent armor as shown in FIG. 1 but also including a breather and/or pressure release system.
 FIG. 3 is a cross-sectional view of another embodiment of spaced transparent armor similar to that of FIG. 1 and according to the invention, but including a secondary seal between the armor components.
 FIG. 4 is a cross-sectional view of another embodiment of spaced transparent armor according to the invention and generally similar to that of FIG. 1 but including a lateral support (typically aluminum) as well as the spacer material and seal adhesive, and showing the transparent armor fitted inside a gasket and the assembly seated in the vehicle window frame.
 FIG. 5 is a cross-sectional view of another embodiment of spaced transparent armor similar to that of FIG. 4 and according to the invention, but including a secondary seal between the armor components.
 FIG. 6 is a cross-sectional view of another embodiment of spaced transparent armor according to the invention and generally similar to that of FIG. 4 but not including a lateral support, and using a different type of seal adhesive than would typically by used in the embodiments shown in FIGS. 1-5.
 FIG. 7 is a cross-sectional view of a typical spaced transparent armor for an architectural application, according to the prior art.
DRAWINGS LIST OF REFERENCE NUMERALS
 The following is a list of reference labels used in the drawings to label components of different embodiments of the invention, and the names of the indicated components.  10a transparent armor component or subassembly  10b transparent armor component or subassembly  12 spacer material  14 secondary seal  15 hydrophobic coating  16 seal adhesive  18 lateral support  19 glazing tape  20 tube for breather and/or pressure release system  22 gasket  24 vehicle window frame  61 silicone seal  62 setting block  63 window frame element  64 metallic frame element  65 fastener
 Referring now to FIG. 1, in one embodiment of the invention a spaced transparent armor (system) is provided as a stack of two transparent armor components (or subassemblies) 10a 10b separated and held in spaced apart relation by spacer material 12 disposed along typically all of (but at least part of) the (outer) periphery of the armor components, creating a gap or space of a thickness of at least a nominal 1/8'' (at least about 3 mm) between the two components; in addition, a seal adhesive 16 adheres the transparent armor components 10a 10b to the spacer material 12 so as to form an integral assembly. In some such embodiments, the seal adhesive may also adhere the integral assembly to a vehicle window frame 24 suitable for installing in a vehicle, so that the spaced transparent armor is useable as a window or windscreen. (In other such embodiments, the integral assembly is not adhered to a vehicle window frame, but instead seated in a gasket, which is in turn seated in a vehicle window frame, as shown in FIG. 6 and discussed in more detail below.) In applications where the seal adhesive is applied in the form of a liquid (such as a two-part RTV, as described in more detail below), glazing tape 19 is applied on the vehicle window frame so as to allow pouring the liquid into the cavity formed by the transparent armor components 10a 10b, spacer material 12, and vehicle window frame 24.
 Still referring to FIG. 1, the seal adhesive 16 keeps the gap or space isolated from the air outside the gap or space, even during vehicle operation with the attendant forces of vibration and other forces, such as twisting or torsional forces on account of the vehicle flexing or contorting as it travels over uneven terrain.
 In some applications and as shown in FIG. 1, a hyrdophobic coating 15 is applied to the surfaces of the transparent armor components that define the gap or space, so that in the very unlikely case of a failure of the seal adhesive 16 there is some resistance to condensation forming evenly over these surfaces.
 Either or both of the transparent armor components 10a 10b may comprise a single layer of material or may comprise a laminate of two or more layers of ballistic materials (two or more layers of ballistic materials, such as glass or borosilicate or some kinds of plastic, separated by so-called inter-layers of typically PVC or urethane, and laminated using an autoclave, to produce a single rigid structure). The transparent armor components 10a 10b may be identical in composition or may be of different compositions. For instance, one may be a single layer of glass and the other may be a laminate of multiple layers of glass or other ballistic materials.
 The gap or space may be filled with simply air, or instead with one or another gas such as argon, in order to keep moisture out of the gap or space.
 The seal adhesive 16 shown in FIG. 1 (and the embodiments shown in FIGS. 2-5) is typically applied as a liquid--e.g. it is poured into a cavity between formed by the edges of the transparent armor components and spacer material (or secondary seal in some embodiments, as described below), and the glazing tape. It cures and forms a relatively solid airtight structure adhering to whatever it is in contact with when it is applied.
 More specifically, the seal adhesive for the embodiment shown in FIG. 1 (and also the embodiments shown in FIGS. 2-5) can be any sort of adhesive and structural agent, but the inventor has found that one seal adhesive material that works particularly well is an RTV-2 elastomer, i.e. a two-part RTV (Room Temperature Vulcanizing) elastomer. RTV elastomers (sometimes called RTV silicone) are all constructed of reactive oil base polymers combined with strengthening mineral fillers. An RTV-2 elastomer, in general, is a product consisting of two components that, when mixed, cure at room-temperature to a solid elastomer, a gel, or a flexible foam. RTV-2 remains flexible from -80° C. to +250° C. The inventor uses an RTV-2 that cures to a solid elastomer. Such an RTV-2 is made by Silicones, Inc., and sold as RTV-2 GI 311, and is available from Polymer Tooling Systems, Exton, Pa. (under the Silicones, Inc. part number). (The two-part RTV comes as a base and hardener, and it is possible to use a different, faster, hardener, called an ultra-fast hardener, instead of the hardener that is ordinarily provided.) According to Silicones, Inc., its GI-300 series RTV silicone rubbers are two component, condensation reaction, tin catalyzed systems that cure at room temperature. They are low viscosity compounds with a variety of hardnesses that can be cured at room temperature in 16 to 18 hours, but can be cured in less time using a faster hardener. They have excellent chemical resistance and outstanding heat resistance.
 A one-part RTV, i.e. a so-called RTV-1 elastomer/silicone, may also be used for the embodiment shown in FIG. 1 (and also the embodiments of FIGS. 2-5). RTV-1 silicone hardens directly under the action of atmospheric humidity. The curing process begins on the outer surface and progresses through to its core. The product is either in a fluid or paste form, but for practicing the present invention, the fluid form is preferable. RTV-1 silicone has good adhesion, elasticity and durability characteristics.
 Another possible seal adhesive material is any of a number of the urethane products manufactured by 3M® such as those made available from R. S. Hughes, Inc. (distributors), accessible over the Internet as rshughes.com.
 The spacer material 12 can be any material, such as a hard rubber, suitably sized, and may be disposed along the entire periphery of the armor components, or only in some places along the periphery. Another suitable spacer material that is sometimes suitable (depending on the desired gap or space between armor components) is so-called swiggle, used in architectural double-pane windows. Preferably, whatever is used as spacer material should include dessicant. Swiggle typically comes as an oscillating ribbon of aluminum, embedded in dessicant-bearing urethane.
 Another type of spacer is a hollow aluminum tube, often of rectangular cross section, with holes through the tube sides, and dessicant inside the tube, and urethane or other sealant/adhesive on one side of the tube. Such a spacer is placed between window panes, or in the present invention, between armor components, with the urethane bearing side outermost, away from the gap or space between the armor components, and so that holes in the side of the tube facing inward toward the gap or space are open, thus exposing the dessicant to the air in the gap or space.
 Still referring to FIG. 1, the (optional) hydrophobic coating 15 may be e.g. a nanotechnology hydrophobic coating of a sort provided by Aculon, accessible over the Internet as aculon.com. Alternatively, any of a number of easy-to-use spray-on hydrophobic coatings may be applied.
 Referring now to FIG. 2, in another embodiment of the invention, a spaced transparent armor (system) is provided as shown in FIG. 1 (except for the optional hydrophobic coatings), but so as to include in addition a breather and/or pressure release system comprising one or more tubes 20 each having an opening in the gap or space between the gap or space, and another opening outside the transparent armor, so as to allow air to pass from the gap or space to outside, and vice versa. The tubes 20 thus penetrate the seal adhesive 16 and the spacer material 12, creating passageways through the seal adhesive 16 and the spacer material 12 allowing air to pass through the spacer material and seal adhesive. In some embodiment the passageways are always open, and in other embodiments the passageways are open only under pressure, using a pressure release device (not shown), designed to maintain the gap seal until a ballistic or fragment impact damages the transparent armor system.
 Referring now to FIG. 3, in yet another embodiment of the invention, spaced transparent armor as shown in FIG. 1 is provided (although without the hydrophobic coatings), but having, in addition, a secondary seal 14 (secondary to the seal adhesive) between the spacer material 12 and the seal adhesive 16. The secondary seal 14 may be made of a synthetic material.
 Referring now to FIG. 4, in yet another embodiment of the invention, spaced transparent armor as shown in FIG. 1 is provided, but instead of the seal adhesive 16 adhering the armor components 10a 10b and spacer material 12 to the vehicle window frame 24 as in FIG. 1, the seal adhesive 16 adheres the armor components 10a 10b and spacer material 12 to a lateral support 18, typically made from aluminum. The assembly including the lateral support, seal adhesive, spacer material and armor components, is then able to be seated in the vehicle window frame on top of a gasket 22.
 Referring now to FIG. 5, an embodiment of the invention the same as in FIG. 4 is shown, but including the secondary seal 14 disposed between the spacer material 12 and the seal adhesive 16, a secondary seal such as also shown in the embodiment illustrated in FIG. 3. The gasket 22 is typically made of rubber or other suitable synthetic materials. The secondary seal 14 is typically made of synthetic or other suitable materials, suitable for serving as a seal, but not having to serve as an adhesive of any significant strength (because the seal adhesive 16 serves that function).
 Referring now to FIG. 6, an embodiment of the invention is shown in which a seal adhesive 16 is used, of a type that is provided as a structural adhesive tape. (The thickness of the tape is exaggerated in FIG. 6, for clarity.) The tape is wrapped around and adheres to the spacer material 12 and the armor components 10a 10b, creating an integral assembly, which is then placed into the vehicle window frame 24, on top of a gasket 22. After wrapping the tape, in some embodiments the entire integral assembly is placed in an autoclave and undergoes a short autoclave cycle. No (aluminum) lateral support, such as shown in FIG. 4, is needed in this embodiment. A structural adhesive tape suitable for practicing the invention as in the embodiment shown in FIG. 6 is manufactured by 3M® and is available as 3M® VHB® Tape 5962. It is described as very conformable foam, modified acrylic adhesive, black, having a thickness of 0.062 in. (1.55 mm).
 As stated previously, the transparent armor components 10a 10b may be made of one material or a system of materials designed to be optically transparent, yet like traditional armor, protect from fragmentation or other ballistic impacts. As mentioned, the transparent armor components 10a 10b use layers of material such as glass separated by polymer interlayers, i.e. sheets of polymers (e.g. PVCs), that adhere the layers of glass together during a lamination process in which the layers of glass with the interlayer between them are placed in an autoclave for an autoclave cycle of operation, during which the assembly is exposed to elevated temperature and pressure.
 In an illustrative transparent armor comprising two transparent armor components 10a 10b with a gap or space between the armor components, the layup is as follows:
First Transparent Armor Component:
 Layer 1: glass, 8 mm (0.25 inches) thick, 1.0 lbs.
 Layer 2: PVB, 1 mm (0.025 inches) thick, 0.1 lbs.
 Layer 3: glass, 8 mm (0.25 inches) thick, 1.0 lbs.
 Layer 4: PVB, 1 mm (0.025 inches) thick, 0.1 lbs.
 Layer 5: glass, 8 mm (0.25 inches) thick, 1.0 lbs.
 Layer 6: plastic, 0.8 mm (0.025 inches) thick, 0.15 lbs. Gap: 10 mm
Second Transparent Armor Component:
 Layer 1: glass, 8 mm (0.25 inches) thick, 1.0 lbs.
 Layer 2: PVB, 1 mm (0.025 inches) thick 0.1 lbs.
 Layer 3: glass, 8 mm (0.25 inches) thick, 1.0 lbs.
 Layer 4: PVB, 1 mm (0.025 inches) thick, 0.1 lbs.
 Layer 5: glass, 8 mm (0.25 inches) thick, 1.0 lbs.
 Layer 6: plastic, 0.6 mm (0.025 inches) thick, 0.15 lbs.
 The above illustrative armor composition should not be construed to limit transparent armor according to the invention to two transparent armor components and a single gap or space. Transparent armor according to the invention has a minimum of two transparent armor components separated by a gap or space, but may have more transparent armor components, each armor separated from the next by another gap or space. The single gap or space described above is 10 mm, but in some embodiments may be larger or smaller, although it typically at least 5 mm, and in case of more than one gap (because of more than two transparent armor components) the different gaps may be different sizes.
 Both the vehicle window frame 24 and, when used, the lateral support 18, are made of rigid materials. The vehicle window frame 24 is made of a metal or a composite, such as fiberglass or other fibers in a resin system. The lateral support 18 can be made of metal, plastic, polymer or composite. Typically, the vehicle window frame and/or the lateral support in any particular embodiment of the invention is made entirely of one material, e.g. the entire vehicle window frame may be made of either metal or composite, and the entire lateral support may be made of either metal, plastic, polymer or composite. When both the vehicle window frame and the lateral support are present in an embodiment of the invention, they do not need to both be made of the same material. Thus, a metal vehicle window frame and a plastic lateral support may be used together.
 The vehicle window frame 24 is used to hold the inner materials in place and permits the entire assembly to be mounted on vehicles. The lateral support 18 provides containment and support of the inner materials.
 In some embodiments, such as the embodiment illustrated in FIG. 1, the transparent armor is mounted to a vehicle by attaching the vehicle window frame 24 to the vehicle body using fasteners such as bolts or other suitable fasteners. In other embodiments, such as the embodiment illustrated in FIG. 4, the vehicle window frame 24 may be integral with the vehicle, i.e. may not be distinct from the vehicle body.
 All the embodiments shown in FIGS. 1-6 address the problem of vibrational damage to the spaced transparent armor by providing a seal adhesive 16 holding the two or more armor components and spacer material together.
 Referring now to FIG. 7, an embodiment of spaced transparent armor for an architectural application is shown in case of buildings for which physical security is a requirement (such as U.S. embassy buildings), including transparent armor components 10a 10b and spacer material 12, as in the present invention, but including a silicone seal 61 and not including a seal adhesive or comparable element as in the present invention, i.e. not including means for holding together armor components and spacer material so as to resist vibrational and torsional forces such as encountered during vehicle operation, and to maintain a seal over the gap or air space created by the spacer material, despite such forces. A so-called setting block 62 (e.g. a hard rubber) is used to cushion the (typically at least partly glass) armor components 10a 10b from a steel or metallic window frame element 63, typically provided as an angle iron. A second steel or metallic frame element 64, shown attached to the building in which the transparent armor is mounted by a fastener 65, abuts the innermost armor component 10b, completing the window frame.
 It is to be understood that the arrangements shown and described above and in the attachments are only illustrative of the application of the principles of the present invention. Numerous modifications and alternative arrangements may be devised by those skilled in the art without departing from the scope of the present invention, and the appended claims are intended to cover such modifications and arrangements.
Patent applications in class Self-propelled, e.g., tanks, etc.)
Patent applications in all subclasses Self-propelled, e.g., tanks, etc.)