Electronic assembly for standard rack enclosures

Details Electronic assembly for standard rack enclosures Electronic assembly for standard rack enclosures

1999-05-19

2001-04-17

Thompson, Gregory (Department: 2835)

Electricity: electrical systems and devices

Housing or mounting assemblies with diverse electrical...

For electronic systems and devices

C174S0720TR, C312S223200, C361S730000, C361S752000, C361S796000

Reexamination Certificate

active

06219235

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates generally to electronic assemblies, and more particularly to an improved electronic assembly including an input/output bulkhead that can support an increased number of ports and can reduce the difficulties in cable adjustment and installation.
BACKGROUND OF THE INVENTION
Electronic assemblies contain various electronic components that are used in many applications. For example, electronic assemblies contain components that collectively function as switches or router-hubs in network systems. A standard Electronic Industries Association (EIA) 19″ form-factor rack may be used to support a plurality of electronic assemblies.
FIG. 1
a
illustrates a conventional electronic assembly
50
including a chassis assembly
55
that encloses a motherboard
60
, at least one daughter-card
65
, a power supply
70
, blowers
75
, and other components. Ports
80
are attached to the daughter-card
65
and protrude through apertures in the rear panel
85
of the chassis assembly. The ports
80
serve as interfaces between external cable lines and the wiring boards
60
and
65
that support the electronic components in the electronic assembly
50
.
One drawback of the conventional electronic assembly
50
is the number of ports
80
that can be positioned across the width of the electronic assembly
50
is limited by the 19″ mounting rail width of the rack opening. The number of ports
80
in such an electronic assembly is typically limited to a small number, for example, six (6) ports with a 60-position D-sub miniature connectors. Therefore, a conventional electronic assembly is unable to implement a larger-size printed wiring board (PWB) which desirably could support additional ports.
Another drawback arises when the conventional electronic assembly
50
is mounted on a standard rack. Access to the ports
80
from the rear of the rack is difficult or not possible, particularly if the rear of the rack is placed against the wall or if the electronic assembly does not extend to the full depth of the rack. Additionally, from the front side of the rack, it is difficult to manually reach the ports
80
if they are located at the rear. As a result, it is difficult to install, disconnect, or adjust cables that interface with the ports
80
.
Typically, all cables egress and air exhaust occur in the rear panel. This leads to limited access to cables and increased impedance to air exhaust. Moreover, cable egress from the chassis is not controlled adequately and minimum bend radii violations often result, affecting data integrity.
Additionally, in the conventional electronic assembly
50
, the ports
80
are disposed at the rear panel
85
of the chassis assembly
55
and, therefore, prevent a straight front-to-back flow of cooling ambient air. Typically, such conventional apparatus requires the use of the pressurized air-flow system
75
, such as blowers which are more complex in design, contain more parts and are less commercially available in large quantities, thereby leading to higher cost. These blowers also have a high-noise attribute and have a stronger airflow driving capability (which leads to a higher power consumption). The blowers permit air to flow in a serpentine fashion within the chassis assembly
55
to cool the components within the chassis assembly. The direction of the air flow may be illustrated by arrows
90
. The air will then exit through a side panel
95
of the chassis assembly
55
. However, the pressurized air-flow system
75
leads to additional cost, power requirements, and noise, and is generally less efficient at cooling. A further drawback in the above-mentioned approach is a daughter-card
65
portion adjacent to the rear panel
85
may not be reached by the air flow for proper cooling. Additionally, the airflow
90
is blocked by rack rails or rack components as the airflow exits the side panel
95
.
FIG. 1
b
illustrates another conventional electronic assembly
96
including a chassis assembly
97
that requires internal cables
98
that are routed from leads
99
to the motherboard
60
and the rear panel
92
. The requirement of routing internal cables
98
internally within the chassis assembly
97
leads to increased cost and assembly time. In addition, it is more difficult and costly to repair and service the internal cables
98
.
In the conventional electronic assembly
96
of
FIG. 1
b
, external cables exit the front panel
93
. This configuration adds to difficulties in accessing other electronic equipment on the same rack, since the external cables from the front panel
93
may interfere or block the other rack equipment.
Therefore, there is a need for an improved electronic assembly that can support a greater number of ports, permit easier access for cable installation, removal or adjustment, and provide a more efficient air flow configuration. There is also a need for an improved electronic assembly that achieves the above advantages while remaining compatible with standard form-factor racks, which are typically deeper that they are wide, and in this configuration, integration of motherboard features and function allows for lower assembly and per-piece part cost.
SUMMARY OF THE INVENTION
The present invention provides an improved electronic assembly that can support an increased number of ports, while remaining compatible with standard form-factor racks. One form of the electronic assembly includes a chassis assembly having a base with a defined opening, and a bulkhead coupled to the base and located adjacent to the defined opening. The bulkhead may include a plurality of apertures capable of receiving an increased number of ports as compared to conventional assemblies. The ports couple the printed wiring boards contained in the electronic assembly to external cable lines. The increased number of ports increases the functionality and the switching capability of the electronic assembly.
The opening formed in the base of the electronic assembly permits easy access to the ports and cables from beneath the assembly, particularly if the assembly is mounted on a slide on the rack. As a result, the present invention reduces the difficulties in attaching, adjusting or detaching the cables which interface with the ports. Furthermore, the present invention minimizes the stress and bending of cables that interface with the ports. The chassis assembly portion adjacent to the bulkhead provides sufficient space for cable routing while controlling the bend radius of cables.
The bulkhead of the chassis assembly may be formed from the base or floor of the chassis assembly. This feature leads to the following advantages. First, this feature provides dimensional accuracy for board mounting features located on both planes, since fabrication tolerance is minimized by a one-piece integrated chassis design. Thus, this feature leads to less difficulties in the manufacture of the chassis assembly. Second, an opening in the chassis assembly base is provided to permit easy access to the ports and cables during cable installation, removal, or adjustment. Thus, the present invention can be easily serviced, thereby leading to reduced costs and labor time and lessens the likelihood of damaged connectors and/or mis-connected cables and no-trouble-found service calls.
The present invention, as configured, also provides an electronic assembly with a “straight-through” air flow capability that leads to lower pressure losses and optimized thermal management within the electronic assembly. Air may be received through apertures formed in the chassis assembly front panel and may flow directly within the electronic assembly toward the rear panel of the assembly. The chassis base width does not span the full width of the rack opening, as in conventional assemblies. Therefore, the present invention can provide air flow to cool thermally-sensitive I/O components which may exist within the chassis assembly. Additional apertures for receiving air may also be formed in the bulkhead, thereby providing additional airflow to cool the comp

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