Patent Publication Number: US-6704199-B2

Title: Low profile equipment housing with angular fan

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. Ser. No. 09/899,762, entitled “Low Profile Equipment Housing with Angular Fan,” filed on Jul. 5, 2001, now U.S. Pat. No. 6,512,673 which claims priority to earlier filed U.S. provisional patent application Ser. No. 60/216,055, filed Jul. 5, 2000, both of which are incorporated herein by reference. 
     This application is related to the following co-pending, commonly assigned applications, the teachings of all of which are incorporated herein by reference: U.S. Ser. No. 60/215,952, filed Jul. 5, 2000, entitled “Server Architecture and Methods for Digital Data Processing,” U.S. Ser. No. 60/215,975, filed Jul. 5, 2000, entitled “Low Profile, High Density Storage Array,” U.S. Ser. No. 60/215,997, filed Jul. 5, 2000, entitled “Ventilating Slide Rail Mount,” U.S. Ser. No. 60/215,996, filed Jul. 5, 2000, entitled “Power Supply for Low Profile Equipment Housing,” U.S. Ser. No. 60/215,995, filed Jul. 5, 2000, entitled “Circuit Board Riser,” U.S. Ser. No. 60/244,354, filed Oct. 30, 2000, entitled “Ventilating Slide Rail Mount,” and U.S. Ser. No. 60/244,361, filed Oct. 30, 2000, entitled “Low Profile, High Density Storage Array.” 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention relates to digital data processors, and, in particular, to methods and apparatus for cooling components within a digital data processor or ancillary device. The invention has particular application in compact, “low profile” devices where space is at a premium, airflow paths are restricted and overheating is of concern. 
     Heating is a constant and significant problem in digital data processors. The failure rates of many electronic components increase as operating temperatures rise. This is particularly true of central processing units which, themselves, often generate significant heat. The problem is compounded by the use of more densely packed circuit boards, by faster processor chips, and by the large power supplies needed to support the foregoing. 
     Most often, processors and associated components are cooled by airflow. Fans are typically used to push or pull air from one side of a chassis, across the components, and out the other side of the chassis. Thus, for example, a typical digital data processor includes chassis intake and/or exhaust fans, often with a fan on the central processing unit itself. While the steps of simply providing intake and exhaust fans on a chassis or housing wall, and of providing one or more device fans on critical components, have proven adequate to date, there remains a need to provide for the cooling of even more powerful, and/or more compact systems. 
     One object of the present invention is to provide an improved digital data processor apparatus and methods. 
     A more particular object is to provide such apparatus and methods for cooling components of digital data processors. 
     A more particular object is to provide such apparatus and methods as are particularly adapted to cooling an integrated circuit chip element, such as a central processing unit, utilized in digital data processing apparatus. 
     A still further object of the invention is to provide such apparatus and methods as are adapted for use with web servers and other data processing apparatus that are housed in restricted space, are compact of design and/or are intolerant of overheating. 
     A still further object is to provide such apparatus and methods as can be implemented at low cost. 
     A still further object of the invention is to provide such apparatus and methods as can be adapted or retrofitted to pre-existing equipment, as well as designed for use in new equipment. 
     SUMMARY OF THE INVENTION 
     One or more of the foregoing objects are achieved in accordance with the present invention by a ventilating or cooling device that includes a fan adapted to mount within a housing, such as the housing or chassis of a web server or storage array, and to selectively cool one or more components disposed on a circuit board or chip carrier within the housing. A flow of air may be provided though the housing for general circulation and cooling, and the fan is positioned obliquely to redirect air toward or away from the selected component while maintaining, establishing or reinforcing a flow of air toward other components or along a path to the housing exhaust. The angle of the fan thus integrates the cooling air for the component in the region around the selected component into an airflow pattern through the chassis. By introducing a locally angled flow path, the fan avoids creation of turbulence or a cross-directed wind that would block overall chassis air flow, create back pressure or otherwise diminish the achievable cooling of the chassis components and the device as a whole. 
     In one embodiment the fan may be a muffin fan formed with an integral housing defining a plane of rotation for the fan blade, and mounted so that the fan blade lies at an oblique angle with respect to plane of the underlying circuit board or a component mounted on the board. In other embodiments the fan may mount with an inclination that introduces a downward component of airflow velocity, and/or a side-to-side tilt that directs the stream somewhat to the left or right to define a desired flow pattern within the chassis and around the components mounted in a housing. A particular embodiment mounts at a shallow angle to fit within a broad covered housing or chassis unit of low height, such as a web server or storage array device that mounts in a rack and that is densely populated with many circuit boards and/or other electronic components. The angle of the fan is tilted out of the horizontal plane to place its inlet facing the upstream or cooling inlet side of the housing, such that the air propelled by the fan has components of motion in both downward (toward the component) and downstream (toward an outlet) directions. For a chassis having an air inlet at the front, the fan maintains the coolant flow generally toward the rear of the housing, where vents and/or an outlet fan operate to maintain a suitable flow gradient over all devices in the housing. The angle of the fan may be defined by an integral mounting structure such as angled side plates formed in the exterior portion of the fan framework, or the oblique mounting angle may be achieved by using separate posts, angled mounting plates or other chassis attachments to define the position and orientation of the fan as a whole. 
     In yet further embodiments, the fan may possess an outer frame configured to provide a housing or shroud around the component which is to be cooled, and may have louvers or vents along one side of the shroud to define a desired downstream or side-diverted airflow directionality that integrates into the general circulation through the chassis. 
     The fan may be mounted on a heat sink having a conventional structure, such as a thermally conductive plate having a central flat region, and carrying a plurality of heat-dissipating fins or posts. 
     In accordance with further aspects of the invention, there is provided a component such as a web server in a chassis or housing for use in a digital data processing system. The component has one or more fans that define cooling airflow through the chassis, and includes a circuit element, such as a central processing unit, and an oblique fan as described above that cools the circuit element while integrating its stream into the chassis airflow. The fan may mount on a heat sink and introduce its downstream outflow into an airstream that has been somewhat straightened or blocked by fins of the heat sink, thus reinforcing or enhancing the overall chassis cooling. 
     The aforementioned objects are met by the present invention which provides, in one aspect, a cooling element for components within a digital data processor chassis. The cooling element, a fan or other device for actively inducing airflow, is disposed on or near the component to be cooled. It is disposed at an angle to facilitate a flow of air past the component and into an air stream established in the chassis. 
     Further aspects of the invention provide a cooling element (e.g., angled fan) as described above that includes a mounting plate to facilitate mounting the fan on the component being cooled. 
     Still further aspects of the invention include a mounting plate to mount the cooling element on the component. 
     In another aspect of the invention, a component is disposed within the rear portion of a chassis having a front, middle, and rear portion. The fan is angled toward the rear portion so as to direct airflow towards the component. 
     These and other aspects of the invention are evident in the drawings and in the descriptions that follow. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention will be more fully understood from the following detailed description taken in conjunction with the accompanying drawings, in which: 
     FIG. 1 depicts a cooling element in accordance with the present invention. 
     FIG. 1A depicts the cooling element of FIG. 1 with heat dissipation members shown as posts. 
     FIG. 2 depicts a rear-view of a preferred embodiment of the cooling-element of the present invention. 
     FIG. 3 depicts a digital data processor chassis and circuit assembly having a cooling element in accordance with the present invention. 
     FIG. 4 depicts another digital data processor having the cooling component of the present invention. 
     FIG. 5 is yet another view of the digital data processor of FIGS. 3 and 4 having the cooling component of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS 
     As shown in FIG. 1, a cooling assembly  10  of the present invention has a cooling element  20 , illustratively mounted on a heat sink comprised of a mounting plate  40  and a plurality of heat conductive heat dissipation members, fins  30 . The cooling element  20  includes a fan  22  for directing airflow, and a fan mounting  24  that orients and supports the fan, as discussed further below. The heat sink mounting plate  40  can be used to mount the cooling assembly  10  of the present invention in a digital data processor, and typically a heat generating component such as a microprocessor (not shown) mounts on the plate  40  so as to be cooled. In accordance with a principal aspect of the present invention, the fan  22  departs from the parallel/orthogonal mounting geometry of the prior art, and is disposed over the mounting plate  40  at an oblique angle so as to facilitate the flow of air within the chassis, i.e., to integrate its airflow with the direction of circulation toward the exhaust or air outlet(s) of the chassis. Preferably the fan  22  is positioned relative to the component so as to cool the microprocessor, which as described below, is typically mounted on the heat sink but may, in various embodiments be shifted upstream or downstream with respect to the fan  22 . 
     The conductive heat dissipation members  30  of the heat sink can be a plurality of spaced apart fins (FIG.  1 ), a plurality of posts (FIG.  1 A), or other conductive members which act to draw away and dissipate heat from component mounted on the plate  40  within a digital data processor. Advantageously, by integrating the component cooling air with the chassis airflow, the fan avoids creating flow-obstructing cross-drafts, and directs its stream such that downstream components are also cooled. 
     FIG. 2 depicts a rear-view of the cooling component  10  of a preferred embodiment of the present invention. The cooling component  10  is shown having a cooling element  20  with a fan  22  and fan mounting  24 , the cooling element  20  being disposed on a heat sink mounting plate  40  with a plurality of spaced apart fins  30 . The cooling element  20  is shown disposed at an oblique angle X 0  from the horizontal mounting plate  40 . The angle can be in the range of 0.01° to slightly under 90°, and typically in the range of about 10° to about 45°. An angle of 14° was found suitable for mounting in a covered chassis having a height somewhat under two inches, and the angled fan was found to enhance airflow, allowing a standard muffin fan to have at least a portion of its intake positioned further from the cover, and to form an oblique airflow such that substantially all the incoming air, represented by arrows  26  in the Figure, was directed as an outflow  26 ′ toward the back of the chassis rather than forming turbulent cross flow components. Thus, the angled mounting allowed the normal front-to back airflow to feed directly into the fan, which, moreover was positioned further from the cover or top of the chassis. Thus a freer intake was achieved, and the fan did not have to work against the lowered pressure of airflow orthogonal to its inlet. The downstream outflow was directed toward the back of the chassis rather than transversely, preventing obstructive flow or air stagnation, while the rather slight acute angle still delivered substantial cooling directed at a microprocessor chip mounted on the heat sink below the fan. One skilled in the art will appreciate that the fan can be angled more steeply, in which case it may desirable to position the cooled component, e.g., microprocessor chip, further downstream in the major flow of the fan, rather than mounting it below the fan. In either case, the angled component fan produces a more coherent downstream flow so as to integrate its airflow to cool downstream components within the chassis. 
     FIG. 3 illustrates a digital data processor  50  having a chassis  52  with a cooling assembly of the present invention mounted therein. Four intake fans  56  are provided near the front of the chassis  52  for providing air into the chassis  52 . A power supply  58 , processing unit  54  such as a RISC control chip, and other components  60  such as disk drives are all disposed within the chassis  52 , which, it will be appreciated, is normally closed and covered, so that it has the shape of a broad, flat box of small height. The cooling component  10  of the present invention is also disposed within the chassis  52 . The cooling component  10  is angled that it directs airflow from the front to a direction downwardly and back, so as to provide airflow toward the processing unit  54  and downstream components while also cooling the CPU (not shown) mounted on the heat sink. 
     FIG. 4 is a side perspective view of a digital data processor  50  housed in a chassis  52  with the cooling assembly  10  of the present invention. The cooling component  10  is tilted with respect to the horizontal plane so as to provide airflow toward downstream components such as a processing unit  54  and components  60 . The direction of airflow is shown by the arrows  26 . Two intake fans  56  are illustrated drawing air into the chassis  52  to establish a general flow toward openings or vents (not shown) at or toward the rear of the chassis. 
     FIG. 5 is yet another digital data processor  50  having the cooling component  10  of the present invention. Three intake fans  56  are shown for supplying air to the chassis  52 . In other high-density microprocessor apparatus, such as rack-mounted storage arrays, six or more intake fans may be provided symmetrically positioned on the front panel, and further fans may be mounted on the back panel to enhance outflow. In the embodiment shown in FIG. 5, the fan of cooling component  10  is tilted with respect to the horizontal, and also canted from left to right so that its output draft is directed both back and toward the right. This configuration may be useful to channel airflow to one side where heat-sensitive components reside, to divert airflow around an obstructing but not heat-sensitive component, or simply to re-integrate airflow for more efficient flow toward the exhaust ports of the chassis. Thus, for example when the processor device comprises an array of many large components such as disk drives, that define corridors or a lattice pattern of flow obstruction within the chassis, the angle fan mounting of the present invention may include a lateral tilt to integrate the cooling flow with the chassis circulation. It will be appreciated that several of these cooling assemblies  10  may be disposed within the chassis  52  for directing airflow, and these may be arranged to divert or combine flows. The cooling assembly  10  of FIG. 5 is shown directing airflow toward a processor chip  54  and other circuitry. 
     Various commonly-owned inventive methods and apparatus have been developed to enhance heat dissipation or cooling mechanisms in densely arrayed web server equipment, and these provide a range of architectures and constructions to which the present invention is advantageously applied. For example, co-pending, commonly assigned, U.S. Patent application Ser. No. 60/215,997, filed Jul. 5, 2000, and Ser. No. 60/244,354, filed Oct. 30, 2000, both entitled “Ventilating Slide Rail Mount” describe ventilated slide rail constructions which facilitates the flow of air throughout the chassis. Another commonly owned invention is a high density storage array having a plurality of digital data storage devices and supporting elements for supporting the storage devices and for providing additional airflow space (see commonly assigned, co-pending U.S. Patent application Ser. No. 60/215,975 filed Jul. 5, 2000, and Ser. No. 60/244,361, filed Oct. 30, 2000, both entitled “Low Profile, High Density Storage Array”). Another is an equipment housing offering improved physical layout and circuit connections (see commonly assigned, co-pending U.S. patent application Ser. No. 60/215,996 filed Jul. 5, 2000, entitled “Power Supply for Low Profile Equipment Housing”). Another is a circuit board riser which among other attributes, occupies less space, thereby providing additional space for airflow to travel (see commonly assigned, co-pending U.S. patent application Ser. No. 60/215,995 filed Jul. 5, 2000, entitled “Circuit Board Riser.”) Another commonly owned U.S. patent application, Ser. No. 60/215,952, filed Jul. 5, 2000, entitled “Server Architecture and Methods for Digital Data Processing,” describes a unique architecture for server systems and the monitoring of physical or utilization status. Each of the foregoing constructions is advantageously employed in a system of the present invention and the invention described herein further provides additional cooling benefits in the chassis, allowing for the cooling of such densely packed, and more compact systems, and is compatible with, or extends each of the above inventions, the patent applications of which are all hereby incorporated by reference. 
     Illustrative embodiments of the invention being thus described, variations, modifications and adaptations to various processing devices and chassis configurations will occur to those skilled in the art, and these are considered to be within the spirit and scope of the invention. Accordingly, the invention is not to be limited by what has been particularly shown and described, but is understood to encompass such variations, modifications and adaptations as will occur to those skilled in the art, as defined by the claims appended hereto and equivalents thereof. 
     All publications and references cited herein are expressly incorporated herein by reference in their entirety.