Patent Application
20090147464
This invention relates generally to a ventilation assembly for computer systems providing improved thermal and EMI shielding performance, and more particularly, to blindswap cassettes having such ventilation assemblies for computer cards arranged in computer card sleds.
Market demands for processing intensive applications have resulted in an ever increasing demand for computing systems that operate at higher speeds. In addition, market preferences generally dictate that smaller system packages are preferred to larger system packages. Typically, computer systems are cooled by one or more fans mounted to the interior of a chassis that blow air across the applicable electronic components and transfer heat through convection.
The trend towards smaller packages, while at the same time increasing the available computing power of the systems, has increased the amount of heat generated within the systems. Thus, effective and reliable cooling has become more important while maintaining adequate EMI shielding.
In addition to such computing systems, subassemblies, such as sleds for an array of PCI or PCIE cards, also generate significant amounts of heat and require effective cooling. Cooling assemblies for such devices also require that EMI be minimized.
Failing to provide adequate cooling can result in the loss of valuable computing resources, as well as the expenditure of increased resources to recover lost data. Thus, achieving market place success dictates that manufacturers design increasingly efficient mechanisms and systems for dissipating heat within a computer system without significantly increasing costs, complexity, or package size.
In accordance with one aspect of the invention, there is provided an assembly for dissipating heat generated by electronic components housed, for example, within a computer chassis. A computer chassis may be dimensioned to substantially enclose electronic components. The computer chassis may include at least one ventilating panel. The ventilating panel may include a plurality of vent holes from perforations typically arranged thereon. The vent holes are typically arranged in at least two rows, wherein the vent holes are sized such that a first plurality of the vent holes are larger than a second plurality. Preferably, larger vent holes are arranged adjacent smaller vent holes on the sides thereof. In a more specific aspect, the arrangement of rows in any row is such that a pair of smaller vent holes is followed in sequence by a larger vent hole, and then by a smaller pair of vent holes, and so on. An adjacent row is staggered in the same manner, but in reverse order such that pairs of smaller vent holes in the adjacent row are arranged in such a manner as to be aligned with the larger vent holes of the first row. In this manner, adequate air circulation is maintained while EMI is minimized as compared to a prior art arrangement having only larger vent holes.
Another aspect the invention relates to a computer chassis panel that includes an arrangement of vent holes substantially as described with respect to the aforementioned assembly embodiment.
Further alternative embodiments of the invention relate to a blindswap cassette. The cassette is typically of the type used for assembling computer cards in an aligned manner within a cassette sled. Such cassette sleds are typically used for holding computer cards such as PCI and PCIE cards therein as part of an overall computer assembly. The blindswap cassette may include an engagement member for having a computer card held thereon, such as a slot, so that the computer card can be guided and secured within a sled. A securing clip may be provided for releasably securing the blindswap cassette within the sled. The engagement member may include a plurality of vent holes arranged so at least along one side thereof there are at least two rows of vent holes resulting from perforations in the engagement member. The vent holes may be arranged in a manner substantially as previously described. Preferably, the arrangement of vent holes is provided on both sides of the cassette, and specifically, the engagement members. In a more preferred aspect, each row is arranged such that two smaller vent holes are on either side of a respective larger vent hole. A second row may be adjacent to the first row and has a similar vent hole arrangement, but may be staggered relative to the first hole such that pairs of smaller vent holes of the second row are arranged adjacent to a larger vent hole of the first row.
These and other advantages and features that characterize the invention are set forth in the claims annexed hereto and forming a further part hereof. However, for a better understanding of the invention, and of the advantages and objectives obtained through its use, reference should be made to the Drawings, and to the accompanying descriptive matter, in which there are described exemplary embodiments of the invention.
Embodiments consistent with the principles of the present invention provide, among other features, a ventilating arrangement for computer assemblies. Such a ventilating arrangement provides adequate ventilation while improving EMC. The computer assemblies may include a chassis containing electronic components therein. The ventilating arrangement may be provided on one or more panels thereof. In a more specific aspect, the ventilating arrangement may be provided on blindswap cassettes for computer cards, such as PCI and PCIE cards. Such cards are typically mounted in card sleds and are part of larger and more complex computer assemblies. Such blindswap cassettes are typically used to secure a card thereon and to guide them into corresponding slots, for example, in a cassette sled. There is typically a plurality of blindswap cassettes and cards mounted within a single sled for connection to the remaining electronic components.
The ventilating arrangement includes at least two rows of vent holes. Some of the vent holes may be smaller in size than other vent holes and may be arranged in a specific configuration to enhance ventilation. This enhancement may improve thermal performance while minimizing EMI. In accordance with aspects of the invention the aperture size of the vent holes made by perforations are minimized as compared to the prior art without impacting air flow pressure impedance. By replacing a selected number of large aperture vent holes with smaller ones, air flow is maintained as a result of using smaller holes, albeit in a larger number. More specifically, in accordance with aspects of the invention, a perforation pattern of one larger and two smaller apertures, or vent holes, is provided in a first row. A second row of vent holes resulting from such perforations may be staggered such that the larger vent holes are aligned with two smaller vent holes of the first row. By staggering the small and large vent holes, the effective vent hole size is close to that of the smaller aperture.
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More specifically, as a result of the arrangement of the invention, resistance to airflow is decreased as shown in the table. This test was done with all electronic components turned off as the test was concerned only with airflow testing. When the system was turned on significant improvement in EMI shielding was observed in the 2.5-5 GHz range.
While the present invention has been illustrated by a description of various embodiments and while these embodiments have been described in considerable detail, it is not the intention of the Applicants to restrict, or any way limit, the scope of the appended claims to such detail. The invention in its broader aspects is therefore not limited to the specific details, representative apparatus, and illustrative examples as shown and described. Accordingly, departures may be made from such details without departing from the spirit or scope of Applicants' general inventive concept. Having thus described the invention, the same will become better understood from the appended claims in which it is set forth in a nonlimiting manner.
