Electricity: conductors and insulators – Anti-inductive structures – Shielded
Reexamination Certificate
1999-08-09
2001-06-26
Berhane, Adolf Deneke (Department: 2838)
Electricity: conductors and insulators
Anti-inductive structures
Shielded
C361S818000
Reexamination Certificate
active
06252180
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
The present invention is directed, in general, to electronic equipment and, more specifically, to an electromagnetic interference (EMI) cover for a conduit, method of manufacturing the EMI cover and an electronic equipment chassis employing the same.
BACKGROUND OF THE INVENTION
Electronic equipment in the telecommunications industry, as well as other industries, is generally designed using a modular format. The modular subassemblies that make up an electronic assembly are generally housed in a chassis including multiple racks with modular compartments.
The modular design provides several advantages including reliability, ease of maintenance and economic savings. For example, if a module in the electronic assembly malfunctions, a service technician can remove and replace the malfunctioning module without taking the system employing the module out of service. If necessary, the malfunctioning module can then be repaired at a service location by specialized technicians familiar with that type of module. This permits field maintenance to be carried out by less skilled personnel and also results in a more reliable system.
The type of chassis to accommodate the modules vary depending on the environment where the equipment is located. For instance, U.S. patent application Ser. No. 09/069,368, entitled “Modular Power Supply Chassis Employing a Suspended Bus Bar Assembly,” by Byrne, et al., commonly assigned with the present invention and incorporated herein by reference, discloses an open rack assembly that accommodates modules with an exterior cabinet enclosing the electronic equipment. Regardless of the chassis type and environmental factors, the electronic assembly provides the framework to deliver electrical power to or from the modules and provides electrical connectivity between the modules.
Various electrical conductor and connector arrangements have been configured to provide electrical connectivity between modules. Such arrangements include electrical wires bundled together or separate wires running from one location to another as well as other configurations. A common method to provide electrical connectivity between modules is to route the electrical conductors through conduits of the chassis support framework housing the modules.
A concern associated with the distribution of power in the modular system is minimizing the level of electromagnetic interference (EMI) emissions radiated from the system. In the case of electrical wiring being routed through the support members of the chassis framework, generally, the conduit includes apertures to allow for routing wires in and out of the conduit and to provide the necessary connections with the various electronic modules. The apertures, however, permit EMI emissions generated by high frequency switching within power modules to escape from the conduit that, unless controlled, may exceed agency limits and impair the performance of the surrounding electronics. Typically, the EMI emissions are minimized by high frequency filtering and by using gasketing material to cover the apertures. Filtering and EMI gasketing materials, however, are expensive and not preferred solutions to such problems.
Not only can the apertures permit an unacceptable level of radiated EMI emissions, the apertures may also weaken the structure supporting the conduit. If the conduit also serves as a support member of the chassis, additional support structure may be required. Generally, providing additional structural members to a chassis is undesirable because of the increased cost, space and weight considerations.
Another consideration associated with the control of radiated EMI emissions in the modular electronic assembly is the establishment of a low impedance connection that provides a common voltage potential between the chassis and the module case (such that gaps between the chassis and the module case are ineffective antennae for radiating EMI). Although the conductive module case can be coupled to the chassis with a separate wire or by other direct contact between the chassis and the module case, these approaches exhibit characteristic impedances that are too high to be effective for controlling EMI. Even in situations where a common voltage potential is established between the module case and the chassis by direct contact, the degree of design tolerance necessary to provide a common path for the modular case to the chassis generally increases total manufacturing cost and decreases reliability.
Accordingly, what is needed in the art is a device for use with a conduit employable in an electronic equipment chassis that establishes a common voltage potential between the chassis and the case of an electronic module to reduce EMI emissions associated with the electronic module.
SUMMARY OF THE INVENTION
To address the above-discussed deficiencies of the prior art, the present invention provides for use with an electronic equipment chassis having a module support member adapted to receive an electronic module and having a conduit containing an electrical conductor proximate the module support member, an electromagnetic interference (EMI) cover, method of manufacturing the EMI cover and electronic equipment chassis employing the same. In one embodiment, the EMI cover includes a conductive body that substantially conforms to the conduit and a boss extending from the conductive body and configured to contact a conductive case of the electronic module. The boss provides a conductive path between the conduit and the electronic module to establish a common voltage potential therebetween thereby reducing EMI emissions associated with the electronic module.
The present invention, in one aspect, provides an EMI cover for a conduit that provides a conductive path between the conduit and the electronic module to ultimately reduce the EMI emissions associated therewith. The EMI cover also adds to the structural integrity of the conduit to afford additionally stiffness thereto. This is especially beneficial when the conduit has apertures located therein that permit, for instance, electrical wiring to be routed through the conduit. Under such circumstances and, in general, the EMI cover also reduces EMI emissions associated with the conduit itself.
In one embodiment of the present invention, the conductive body has a plurality of bosses. The plurality of bosses may engage a single electronic module or, alternatively, each engage a separate electronic module. When each boss engages a separate module, the bosses generally are part of separate sections of the EMI cover. Under such circumstances, it is important that the sections are electrically coupled, but mechanically independent. In a related, but alternative embodiment, the conductive body may include compression tab(s) configured to assert pressure against the conduit to further facilitate contact between the conduit and the conductive case of the electronic module(s). When the conductive body includes a plurality of compression tabs and bosses (arranged in separate sections) to engage a corresponding plurality of electronic modules, the compression tabs also facilitate mechanical independence between the separate sections of the EMI cover.
In one embodiment of the present invention, a tab is located on the conductive body configured to be received by a corresponding receptacle on the conduit. The tab facilitates alignment of the EMI cover with respect to the conduit and, also, provides an additional mechanism in conjunction with the receptacle to secure the EMI cover to the conduit. Of course, the alignment and securement tab is not necessary to practice the present invention.
In one embodiment of the present invention, the conductive body has a first edge and a second edge configured to allow the EMI cover to engage the conduit. The first and second edges, therefore, facilitate attachment of the EMI cover to a conduit of any geometry (e.g, rectangular). The advantages associated with the first and second edges will become more apparent with reference to the drawings and related descript
Buskmiller Michael R.
Byrne Vincent M.
Fontana Edward C.
Mandelcorn Yehoshua
Berhane Adolf Deneke
Lucent Technologies - Inc.
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