Ruggedized electronics enclosure

Details Ruggedized electronics enclosure Ruggedized electronics enclosure

2002-08-30

2004-07-20

Thompson, Gregory D. (Department: 2835)

Electricity: electrical systems and devices

Housing or mounting assemblies with diverse electrical...

For electronic systems and devices

C165S080300, C165S185000, C312S326000, C361S700000, C361S703000, C361S704000, C361S707000, C361S694000, C361S695000, C361S688000, C454S184000

Reexamination Certificate

active

06765793

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention is related to enclosures for electronic circuits and particularly to ruggedized enclosures for use in installations subjected to hostile environments including destructive shock events and destructive vibration events. In one embodiment, the invention may operate without requiring additional mechanical isolation.
2. Description of the Related Art
Conventional ruggedized electronics enclosures are often employed in military applications. The environments in which military electronic circuits must be able to operate typically present conditions outside of a commercial electronic circuit's operational parameters. Examples of such conditions include excessive moisture, salt, heat, vibrations, and mechanical shock. Historically, military electronic equipment was custom made to provide the required survivability in the hostile environments. While effective in surviving the environment, custom equipment is often significantly more expensive than commercial systems, and is typically difficult if not impossible to upgrade to the latest technologies. Therefore, a current trend in conventional military hardware is to adapt commercially available electronics for use in military applications. These systems are typically known as Commercial Off The Shelf systems, or COTS.
The COTS design philosophy has allowed the military to keep current with technological innovations in computers and electronics, without requiring specialized and dedicated electronic circuit board assemblies. The COTS design methodology is attractive because of the rapidly increasing computational power of commercially available, general-purpose computers. Since the components in a COTS system are commercially available, though usually modified to some extent, the military can maintain an upgrade path similar to that of a commercial PC user. Thus the COTS philosophy allows the military to integrate the most potent electronic components available into their current hardware systems.
While COTS systems have allowed the military to reduce the cost of equipment and to make more frequent upgrades to existing equipment, there are inherent disadvantages to COTS systems. As noted above, military applications must be able to withstand various environmental extremes, including humidity, temperature, shock and vibration. These conditions are typically outside of the operating parameters of commercial electronics and, thus, added precautions and modifications to the physical structures of the equipment must be made to ensure reliability of operation in these environments. Conventional COTS systems typically use two specialized modifications to maintain reliability. These approaches may be used separately, or in combination.
To deploy COTS equipment in hazardous environments, COTS components are housed in a complex ruggedized enclosure or case. One approach, sometimes referred to as “cocooning” places a smaller, isolated equipment rack within a larger, hard mounted enclosure. With this approach shock, vibration and other environmental extremes are attenuated by the isolation system to a level that is compatible with COTS equipment. Another approach, sometimes called Rugged, Off The Shelf (ROTS) seeks to “harden” the COTS equipment, in a manner such as to make it immune to the rigors of the extended environmental conditions to which it is exposed. This later approach strengthens the equipment's enclosure and provides added support for internal components. Both cocooning and ROTS design methodologies must also improve cooling efficiency to accommodate higher operating ambient temperatures. Both approaches suffer from added complexity, size, weight and cost.
The size and complexity exacerbates heat-removal from the enclosure and often complex heat flow routes must be devised in order to maintain a desirable operating temperature. Taken together, these design considerations drastically increase the cost and complexity of such an enclosure.
Commercial systems are typically designed around three main criteria, cost, time-to-market and easy expansion. To deliver on all three design goals, the assumption is that the environment for the system will not be exposed to extreme environmental conditions. Cost is the primary motivator to keeping the packaging simple and inexpensive. The package support structures may have a low cost to keep the system cost from escalating. Keeping costs down to a minimum is counter to the requirements of making a system robust enough to survive a military environment.
To easily accommodate system expansion, computer manufacturers try to simplify the installation of peripheral cards, memory and storage. The idea of having a minimum number of fasteners (i.e., a snap-in-place design) allows the customer easy access and installation of peripherals. The design's modularity preserves the customer's investment. When you couple the commercial constraints with the requirements of the military environment, the design requires a different approach, typically moving the structural changes to the system enclosure and it's attachments. The usual cocooning approach is to design the enclosure to absorb as much of the shock as possible to allow the incumbent system to survive the environment. In practice, this is not easily achieved, especially when using larger, and heavier computer systems. Thus, the idea of completely isolating a commercial system from the rigors of the military environment is difficult to achieve and adds a large cost premium because the rack is the item being modified. The current solution to supporting COTS technology in a military environment described above, adds significant complexity to the system.
Two of the most difficult conditions to design for are vibration and mechanical shock. Mechanical shock and vibration may over time destroy electronic equipment by deforming or fracturing enclosures and internal support structures and by causing electrical connectors, circuit card assemblies and other components to fail. In military applications, as well as in commercial avionics and the automotive industry, electronics must be able to operate while being subjected to constant vibrational forces generated by the vehicle engines, or waves, as well as being subjected to sudden, and often drastic, shocks. Examples of such shocks are those generated by bombs, missiles, depth charges, air pockets, potholes, and other impacts typically encountered by military or commercial vessels. Furthermore, these conditions may also be seen in the operating conditions of a network or telephone server during an earthquake. While providing some protection from shock and vibration, the conventional ruggedized enclosure operating alone cannot provide adequate protection for mission-critical electrical components and circuits.
In order to provide additional protection against shock and vibration, conventional COTS systems mount the ruggedized enclosures described above in a mechanically isolated cocoon.
FIG. 1
illustrates a conventional mechanically isolated cocoon. As illustrated in
FIG. 1
, a cocoon
100
is provided to house the various ruggedized enclosures
110
. The cocoon
100
may be attached to a floor
130
and/or a wall
140
of its surroundings. Commonly this includes the fuselage or deck plate of a military vehicle. The cocoon
100
is attached to the surroundings
130
,
140
via mechanical isolators
120
. A particularly advanced mechanical isolator
120
is the polymer isolator illustrated in
FIG. 1
, though conventional systems may use any spring-like apparatus to provide the isolation. By attaching the cocoon
100
to its surroundings
130
,
140
via mechanical isolators
120
, the cocoon
100
is allowed limited movement with five degrees of freedom. This limited movement helps to dampen the effects of shock and vibration.
There are several drawbacks to using the mechanically isolated cocoon
100
. In order to reduce the shock to the equipment, the cocoon
100
must be provided with a sway space
150
in which it may m

Affiliated with

Also associated with

Rating

Ruggedized electronics enclosure does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Ruggedized electronics enclosure, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Ruggedized electronics enclosure will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-3249705