Air flow system

An apparatus is provided in one example embodiment and includes a faceplate having a plurality of slots arranged on a front portion of the faceplate, a top plate attached to a top portion of the faceplate, and a screen attached to the faceplate and the top plate. A channel may be disposed behind the faceplate and between a bottom surface of the top portion of the faceplate, a bottom surface of the top plate and a top surface of the screen. The screen may include a plurality of openings. In a specific embodiment, the apparatus may be removably attached to a removable line card of a switch. In a specific embodiment, air may be guided through the slots, by a fan operating behind the apparatus, along the channel and through the plurality of openings to one or more heat generating components on the line card.

TECHNICAL FIELD

This disclosure relates in general to the field of computer and networking systems and, more particularly, to an air flow system for electronic equipment.

BACKGROUND

Over the past several years, information technology (IT) has seen a tremendous increase in performance of electronic equipment, coupled with a geometric decrease in floor space to house the equipment. Further, increased performance requirements have led to increased energy usage, which has resulted in increased heat dissipation within an already-crowded floor space. For example, the rate of increase of heat density for communications equipment was 13% annually from 1992 through 1998, at which time it increased to 28%, and is projected to continue to increase. As a result, data centers are demanding better thermally managed products that have good computing performance coupled with good thermal performance. Thus, there is a need to design electronic equipment with better thermal characteristics.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

Overview

An apparatus is provided in one example embodiment and includes a faceplate having a plurality of slots arranged on a front portion of the faceplate, a top plate attached to a top portion of the faceplate, and a screen attached to the faceplate and the top plate. A channel may be disposed behind the faceplate and between a bottom surface of the top portion of the faceplate, a bottom surface of the top plate and a top surface of the screen. The screen may include a plurality of openings. In a specific embodiment, the apparatus may be removably attached to a removable line card of a switch.

In a specific embodiment, the top plate may be substantially perpendicular to the front portion of the faceplate, and substantially parallel to the top portion of the faceplate. In another specific embodiment, the screen may be substantially parallel to the top plate. In yet another specific embodiment, the top plate may be a substantially solid plate. In still another embodiment, the top plate and the screen may extend along a portion of a length of the line card. The faceplate can include a plurality of openings to accommodate ports in the line card.

In a specific embodiment, air may be guided through the slots, along the channel and through the plurality of openings to one or more heat generating components on the line card. The air may be guided through the slots by a fan operating behind the apparatus. In other example embodiments, the apparatus can include a switch with a plurality of line cards, each line card having modular air flow assembly on a front of the line card, with the modular air flow assembly including the faceplate, the top plate and the screen.

Example Embodiments

Turning toFIG. 1,FIG. 1is a simplified diagram illustrating a perspective view of an air flow system10in accordance with one example embodiment. Air flow system10includes a modular air flow assembly12on a line card14. As used herein, the term “line card” refers to any electronic equipment that includes an electronic circuit (e.g., on a printed circuit board) to communicate data in a network. “Electronic equipment” can include any equipment (e.g., instrument that performs a task) that includes electronic circuitry, such as computers, switches/routers, line cards, smartphones, motherboards, etc. In a specific embodiment, line card14may be removably attached to a switch (or router). The terms “switch” and “router” may be interchangeably used in this Specification to refer to devices that receive and forward packets in the network.

In specific embodiments, line card14may include a plurality of ports16(e.g., ports serve as entry and exit points of data in the switch). In a more specific embodiment, ports16may be configured with high port density (e.g., large number of ports in a relatively small area). Each of ports16indicates an opening, to which a networking cable (e.g., Ethernet cable, fiber optic cable, etc.) can be plugged using a suitable connector (e.g., RJ45 connector, SFP connector, etc.).

Line card14may include a plurality of heat generating components18. Heat generating components18may include any type of electrical circuits, for example, power supplies, signal processors and other semiconductor chips, resistors, memory elements, etc. According to various embodiments, removable modular air flow assembly12can improve airflow without sacrificing electromagnetic interference (EMI) shielding performance in air flow system10.

For purposes of illustrating the techniques of air flow system10, it is important to understand the constraints in a given system such as the system shown inFIG. 1. The following foundational information may be viewed as a basis from which the present disclosure may be properly explained. Such information is offered earnestly for purposes of explanation only and, accordingly, should not be construed in any way to limit the broad scope of the present disclosure and its potential applications.

Most modern communications equipment includes heat generating electronic components that have to be cooled to enable them to perform effectively. Typically, the electronic components are cooled using air that is forced into the equipment chassis and made to flow over the electronic components. In data center environments with large number of electronic components, thermal management can be a challenge. Some data centers utilize a hot aisle/cold aisle layout design for server racks and other computing equipment to conserve energy and lower cooling costs by managing air flow effectively.

In its simplest form, a hot aisle/cold aisle data center design involves lining up server racks in alternating rows with cold air intakes facing one way and hot air exhausts facing another way. The rows composed of rack fronts are called cold aisles. Typically, cold aisles face air conditioner output ducts. The rows, into which heated exhausts pour, are called hot aisles. Typically, hot aisles face air conditioner return ducts. Cool air thus enters at the front, and hot air exits at the back.

Equipment used in such hot aisle/cold aisle data centers may have front-to-back airflow cooling. For example, in a switch comprising a plurality of line cards, the air enters at a front panel faceplate of each individual line card, passes through a mid-plane of the line card, and exits at the back of the switch chassis. The front panel includes perforations, which permit air to enter the chassis. The perforation area can affect board-level (e.g., at the line card level) and system-level (e.g., at the switch chassis level) cooling. However, port density of the line-cards is already quite high, and expected to increase in the future. The increasing number of ports on the faceplate and the limited total exposed area of the faceplate present a challenge in configuring the perforations on the front panel faceplate. Additionally, the power dissipation and cooling demands are increased proportional to the port density. However, with the increased port density, the perforation area is reduced. Thus, the cooling capacity of the line card is reduced.

Moreover, EMI shielding is a consideration in such thermal management systems. EMI refers to disturbance that affects an electrical circuit due to either electromagnetic induction or electromagnetic radiation emitted from an external source. The disturbance may interrupt, obstruct, or otherwise degrade the effective performance of the electrical circuit. The degradation can range from a simple loss of quality data to a total data loss. In general, metallic materials can block the magnetic field that gives rise to EMI, thereby providing effective EMI shielding. The amount of shielding depends upon the material used, its thickness, the size of the shielded volume and the frequency of the fields of interest and the size, shape and orientation of apertures in the shield to an incident electromagnetic field.

Typical materials used for electromagnetic shielding include sheet metal, metal screen, and metal foam. Any holes in the shield should be significantly smaller than the wavelength of the radiation that is being kept out, or the shield may not effectively approximate an unbroken conducting surface. For most high frequency applications, aluminum can be a suitable material choice for the EMI shield; for low frequency applications, steel may be more suitable.

A typical choice for the EMI shield where air flow is also a consideration is an EMI venting screen, which includes a sheet of conductive material having holes in a honeycomb pattern. The shielded honeycomb EMI venting screen may be based on at least three criteria: attenuation (e.g., EMI shielding ability), air flow (e.g., how much static pressure drop is introduced into the system), and mounting (e.g., attachment method). EMI shielding is improved with more conductive surface and less number of openings; on the other hand, air flow is improved with higher number of openings. Thus, configuration of a suitable EMI venting screen may involve a tradeoff between EMI shielding and air flow.

Air flow system10is configured to address these issues (and others) in offering modular air flow assembly12that can improve thermal performance without sacrificing EMI shielding capabilities (among other advantages). Embodiments of air flow system10can increase air flow, reduce system resistance (e.g., pressure) and maintain EMI shielding performance. Air flow system10can be configured to be contained within line card14, requiring no extra space or additional area than already used by line card14. Customizable screens may be configured therein for airflow for each individual line card14having different EMI or air flow requirements. Air flow system10may not affect the system mechanical/EMI shielding design, but provides improved thermal and airflow performance without sacrificing EMI shielding.

Embodiments of air flow system10can include modular air flow assembly12having a solid top plate providing an EMI shielding cover, a screen with openings to provide an air flow path, a slotted faceplate that can provide an unrestricted airflow intake channel and an EMI shielding gaskets/foam that can shield off possible EMI leakage between the components of modular air flow assembly12. In various embodiments, modular air flow assembly12may comprise conductive materials that can provide EMI shielding and thermal conduction. Although modular air flow assembly12is illustrated and described with reference to line card14, it may be noted that modular air flow assembly12may be installed in other devices (e.g., computers, laptops, etc.) where thermal management, EMI shielding, and small form factor (e.g., reduced surface area to place air flow vents) can be particular considerations in design choices.

Note that the numerical and letter designations assigned to the elements ofFIG. 1do not connote any type of hierarchy; the designations are arbitrary and have been used for purposes of teaching only. Such designations should not be construed in any way to limit their capabilities, functionalities, or applications in the potential environments that may benefit from the features of air flow system10. It should be understood that the air flow system10shown inFIG. 1is simplified for ease of illustration.

Turning toFIG. 2,FIG. 2is a simplified diagram showing an exploded view of an embodiment of air flow system10. Modular air flow assembly12may include a faceplate20comprising a plurality of slots22arranged on a front portion thereof; a screen24, comprising a plurality of openings26; and a top plate28, comprising a substantially solid plate. The term “slot” can include an aperture that is relatively longer than it is wide. In various embodiments, top plate28may be detachably attached (e.g., using screws) to faceplate20and screen24. In other embodiments, top plate28may be permanently attached (e.g., welded, brazed, etc.) to faceplate20and screen24. In a specific embodiment, modular air flow assembly12may be detachable from line card14, for example, to facilitate inspecting, or repairing components thereon.

Faceplate20may include openings30on the front portion to accommodate ports16. Faceplate20may include a top portion32and a bottom portion34. Top portion32may facilitate supporting and attaching top plate28to faceplate20with screws or other attachment mechanisms. In a specific embodiment, top portion32may be substantially perpendicular to the front portion of faceplate20, and parallel to bottom portion34. Top plate26also may be substantially perpendicular to the front portion of faceplate20, and parallel to bottom portion34. Bottom portion34may facilitate attaching faceplate20to line card14.

Screen24may have a top surface36that includes a solid portion, and another portion with plurality of openings26. Screen24may also include features (e.g., screw holes, etc.) to detachably attach it to top plate28. In some embodiments, modular air flow assembly12may extend a length L of line card14(where L is measured perpendicular to the front portion of faceplate20). In other embodiments, as illustrated in the FIGURE, modular air flow assembly12may extend along a portion of length L. In various embodiments, faceplate20may include additional features that may be applicable to various pluggable line card functionalities of line card14, such as levers and locking mechanisms to attach line card14to a switch or router.

Turning toFIG. 3,FIG. 3is a simplified diagram showing a cut-out of example details of an embodiment of air flow system10. Faceplate20may be attached to top plate26, for example, with screws38(or other suitable attachment mechanism). Top plate28may be attached to screen24with screws39(or other suitable mechanism). In an assembled configuration (e.g., where top plate28is attached to faceplate20and screen24), modular air flow assembly12may provide a channel40for air flow into line card14.

According to various embodiments, channel40may be disposed behind faceplate20, and between faceplate20, top plate28and screen24. For example, channel40may be disposed behind the front portion of faceplate20, and between a bottom surface42of top portion32of faceplate20, a bottom surface44of top plate28and top surface36of screen24. Channel40may extend from behind the front portion of faceplate20to the opposite end of screen24.

According to various embodiments, air may be guided through slots22, along channel40and through plurality of openings26to one or more heat generating components18on line card14. Air may be guided into a front of line card14in a direction indicated by arrow46through vents22. Air may flow through channel40and through plurality of openings26in screen24, in a direction generally indicated by arrow48. Portions of the air may flow substantially parallel to top plate28, and then bend away (e.g., downwards, or sideways) through openings26. Thus, air may be guided adjacent to (e.g., near, over, around) heat generating components16on line card14. The air may eventually exit line card14at a back (or side portion), thus enabling a front-to-back air cooling system. In various embodiments, a fan (not shown) operating behind line card14may pull in air and push it out of the back of line card14.

Turning toFIG. 4,FIG. 4is a simplified diagram showing a close-up view of some example details of air flow system10. Faceplate20includes openings30to accommodate connectors to ports16, and slots22for channeling air through air flow system10. It should be noted that the openings illustrated in the figure corresponding to ports16are not open all the way through (e.g., to accommodate electronic circuitry of ports16), and therefore, do not provide any air flow. Moreover, when line card14is operational in a suitable switch or router, some or all of the openings for ports16can be closed up with appropriate connectors. In various embodiments, slots22may be joined to create a single slot extending through the length of faceplate20. However, EMI shielding in such a configuration may be proportionately lower.

Turning toFIGS. 5A-5D,FIGS. 5A-5Dare simplified diagrams illustrating individual components of modular air flow assembly12. InFIG. 5A, faceplate20may include opening30to accommodate connectors (e.g., RJ45 connectors or SFP connectors, etc.) corresponding to ports16(not shown) and slots22that can facilitate air flow into line card14. Top portion32and bottom portion34may include attachment means50(e.g., holes, threaded holes, etc.) to attach faceplate20to top plate28and line card14. InFIG. 5B, top plate28may include a substantially solid portion comprising a flat plate and attachment means52(e.g., threaded holes, holes, etc.) to attach it to faceplate20and screen24. In some example embodiments, attachment means52may include screw holes with appropriate indentations to permit top plate28to be screwed to EMI venting plate24.

InFIG. 5C, screen24is illustrated showing attachment means54(e.g., threaded holes, holes, etc.) to attach it to top plate26. In various embodiments, plurality of openings26may be of any shape and size to meet EMI and air flow requirements, as needed. The number, size, and shape of openings26may affect the degree to which screen24provides EMI shielding. Nevertheless, top plate26may provide sufficient EMI shielding so that screen24may be suitably configured to permit maximum air flow through channel40, rather than effective EMI shielding.

A close-up of openings28is also illustrated inFIG. 5D. In some embodiments, openings28may be a hexagonal honeycomb structure configured to improve EMI shielding characteristics. For example, an electromagnetic wave may be reflected off the walls in each hexagonal tube, and a portion of the wave may be absorbed into the material, leading to reduction in EMI leakage. In another example, openings28may be circular (or any other shaped) holes that permit suitable air flow through screen24. For example, openings28may be configured to enable smooth air flow, rather than reduced EMI emission. In some embodiments, screen24may include suitable EMI gaskets that prevent EMI leakage when screen24is mounted on line card14.

Turning toFIGS. 6A-6B,FIGS. 6A-6Billustrate example configurations of experimental setups related to air flow system10. CONFIG 1, indicated as58inFIG. 6A, includes a machined faceplate with no top plate or screen. CONFIG 2, indicated as60inFIG. 6B, includes a sheet metal with 55% perforations and holes on the edges. Air was guided through the faceplates in the two different configurations, and air flow (in cubic feet per minute (CFM)) was measured and compared with modular air flow assembly12according the present disclosure.

Turning toFIG. 7,FIG. 7is a simplified diagram illustrating a graphical comparison66between the airflow measured in the different configurations described with reference toFIGS. 6A,6B andFIG. 1. The X-axis represents the pulse width modulation (PWM) duty cycle in % indicating the power of an electrically powered fan that facilitates guiding air through line card14. For PWM duty cycles greater than 50%, CONFIG 3, representing modular air flow assembly12, shows better airflow compared to the other configurations.

Turning toFIGS. 8A-8C,FIGS. 8A-8Care simplified diagrams illustrating line card14in switch68according to various configurations. In some embodiments, as illustrated inFIG. 8A, line card14may be turned vertically and guided out of a slot in switch68. Captive screws on faceplate20may be loosened, ejector levers pivoted to unlock line card14, and line card14may be slid out of the chassis of switch68. In other embodiments, as illustrated inFIG. 8B, line card14may be placed horizontally in switch68. Any suitable arrangement may be implemented, with front-to-back air cooling facilitated appropriately by air flow system10in line card14.

In various embodiments, as illustrated inFIG. 8C, switch68may include one or more fans70(shown via holes behind the fans) behind line cards14in switch68. During operation, fans70may pull in air from a front of switch68, as indicated by arrow A. Air may flow through slots22, channel40, and through openings28in modular air flow assembly12of each line card14, over heat generating components18of each line card14, and exit out of a back of switch68.

Turning toFIG. 9,FIG. 9is a simplified flow diagram illustrating example operations that may be associated with an embodiment of air flow system10. Operations100may include102, at which faceplate20with slots22may be provided. At104, screen24and top plate28may be provided. At106, faceplate20may be attached to screen24and top plate28to create modular air flow assembly12. At108, modular air flow assembly12may be attached to line card14. At110, line card14may be attached to switch68.

Turning toFIG. 10,FIG. 10is a simplified flow diagram illustrating example operations that may be associated with an embodiment of air flow system10. Operations120may include122, at which air may be guided through plurality of slots22in faceplate20. At124, air may be guided through channel40in modular air flow assembly12. At126, air may be guided through plurality of openings26in screen24. At128, air may be guided adjacent to (e.g., near, over, under, around, etc.) heat generating components18.

It is imperative to note that countless possible design configurations can be used to achieve the operational objectives outlined here. Accordingly, the associated infrastructure of air flow system10may have a myriad of substitute arrangements, design choices, device possibilities, hardware configurations, equipment options, etc. It is also important to note that the operations and steps described with reference to the preceding figures illustrate only some of the possible scenarios that may be executed by, or within, the system. Some of these operations may be deleted or removed where appropriate, or these steps may be modified or changed considerably without departing from the scope of the discussed concepts.

In addition, the timing of these operations may be altered considerably and still achieve the results taught in this disclosure. The preceding operational flows have been offered for purposes of example and discussion. Substantial flexibility is provided by the system in that any suitable arrangements, chronologies, configurations, and timing mechanisms may be provided without departing from the teachings of the discussed concepts.

Although the present disclosure has been described in detail with reference to particular arrangements and configurations, these example configurations and arrangements may be changed significantly without departing from the scope of the present disclosure. For example, although the present disclosure has been described with reference to a line card, air flow system10may be applicable to other devices where a similar tradeoff between EMI shielding and air flow may be desired. In some embodiments, top plate26may be provided for aesthetic reasons, or to protect components underneath. In other embodiments, considerations other than EMI shielding or air flow may drive a similar configuration. All such scenarios are included within the broad scope of the embodiments disclosed herein.

In various embodiments, the elements of air flow system10may be composed of any kind of materials, including metal, plastic, wood, fiber glass, semiconductors, etc., or a combination thereof. In a specific embodiment, modular air flow assembly12may be composed of metallic materials, such as aluminum or steel. While metallic materials may be applicable to considerations of EMI, in devices where EMI is not a consideration, any suitable material, including metallic materials may be used.

While screws and similar attachment mechanisms are illustrated in the figures, it may be noted that any kind of attachment mechanisms may be used, including clips, latches, grooves, or other mating and connection devices. In embodiments where the components are removably attached to each other, the attachment mechanisms may be appropriately configured to enable the components to be removed as needed. In other embodiments, where the components are permanently attached to each other, the attachment mechanisms may be appropriately configured to disable separation between the components without destroying them. Examples of such permanent attachment mechanisms include welding, brazing, gluing, etc.

In terms of the dimensions of the articles discussed herein (e.g., the fan, the plate, the pattern, etc.), any suitable length, width, and depth (or height) may be used and can be based on particular end user needs, or specific elements to be addressed by the apparatus (or the system in which it resides). It is imperative to note that all of the specifications and relationships outlined herein (e.g., height, width, length, hole diameter, # holes per unit of area, etc.) have only been offered for purposes of example and teaching only. Each of these data may be varied considerably without departing from the spirit of the present disclosure, or the scope of the appended claims. The specifications apply only to one non-limiting example and, accordingly, should be construed as such. Along similar lines, the materials used in constructing the articles can be varied considerably, while remaining within the scope of the present disclosure.