Abstract:
A low profile high density rack mountable enclosure with superior cooling and highly accessible re-configurable components is disclosed. One embodiment of the present invention discloses a computer system comprising a chassis for holding a plurality of computer components, a CPU having a heatsink mounted thereon, wherein the CPU is mounted in the chassis, and a first blower having an inlet for receiving air and an outlet for expelling air, wherein the first blower is mounted in the chassis proximate to the CPU. Another embodiment of the present invention discloses a retention clip for use in a computer system, the retention clip comprising a base portion having at least one tab, and a flange portion having at least one mounting hole, wherein the flange portion is connected to the base portion, and wherein the flange portion makes an angle with the base portion. Another embodiment of the present invention discloses a computer enclosure comprising a chassis having a left side, a right side, and a bottom side, wherein a rear edge of the bottom side includes an open hem, a top panel, wherein a rear edge of the top panel includes an open hem, and a rear panel having a left side, a right side, a top side, and a bottom side, wherein the open hem of the bottom side is adapted to receive the bottom side of the rear panel, and the open hem of the top panel is adapted to receive the top side of the rear panel.

Description:
BACKGROUND 
     1. Field of the Invention 
     This invention relates to computer systems, and more specifically, the design and layout of components of computer systems. 
     2. Related Art 
     With the growth of computing applications, there has been an associated increase in the need for servers and larger scale computer systems. These server systems include such components as CPUs, hard drives, CD-ROMs, DVDs, tape backup systems, peripheral cards, monitors, and universal power supplies. 
     Network server components can be mounted vertically on a server rack or cabinet in a dedicated server location, often with temperature, humidity, and particle controls. Using such racks, server components can be stored with high space efficiency, while allowing easy visual and manual access. Server racks and cabinets have standard size mounting holes to which computer equipment can be attached. Rack-mounted equipment are typically provided in unit or “U” sizes. A typical  1  unit (“1U” ) server measures 1.75″ high, 19.00″ wide, and 24.00″ deep. An advantage of a 1U server is that its low profile allows a larger number of devices to be mounted on a given rack. For example, forty-two (42) 1U servers can be mounted in a single 7-foot rack. However, low profile servers such as 1U servers have some disadvantages. 
     One disadvantage is that cooling the various components mounted inside the low profile servers becomes more difficult. As mentioned above, a 1U server is only 1.75″ high. This makes it difficult to circulate air throughout the system and cool the components mounted inside the server such as disk drives and CPU(s). With respect to the CPUs in the system, the cooling problem is compounded since heat sinks that include a dedicated fan cannot be mounted to the CPUs. This is because heat sinks with dedicated fans are too tall to fit inside the 1.75″ chassis. 
     Another disadvantage is that components such as tape drives are difficult to mount inside the low profile 1U chassis. These components often require the use of multiple screws and/or other fasteners to secure the components within the chassis. This makes installation and removal of the components difficult. Further, the screws and fasteners are often dropped or lost within a chassis increasing the possibility of an electrical short. Finally, the components are generally mass produced and include multiple mounting holes into which screws are inserted to secure the components to the chassis. But, since the components are mass produced, hole location tolerances are often exceeded making it difficult or impossible to fasten a screw into each mounting hole. 
     Yet another disadvantage is that conventional chassis in 1U systems, and in particular the rear panels of the chassis, are designed to accommodate a single type of motherboard or printed circuit board (PCB). In other words, the rear panels cannot easily be changed so that the chassis can accommodate multiple types of motherboards. Further, conventional systems that do allow for changing of the rear panels do so by compromising the structural integrity of the chassis. That is, the chassis may sag and place pressure on other servers located beneath the sagging chassis. 
     Accordingly, a computer system that overcomes the disadvantages mentioned above is needed. 
     SUMMARY OF THE INVENTION 
     A low profile high density rack mountable enclosure with superior cooling and highly accessible re-configurable components is disclosed. 
     One embodiment of the present invention discloses a computer system comprising a chassis for holding a plurality of computer components, a CPU having a heatsink mounted thereon, wherein the CPU is mounted in the chassis, and a first blower having an inlet for receiving air and an outlet for expelling air, wherein the first blower is mounted in the chassis proximate to the CPU. 
     Another embodiment of the present invention discloses a retention clip for use in a computer system, the retention clip comprising a base portion having at least one tab, and a flange portion having at least one mounting hole, wherein the flange portion is connected to the base portion, and wherein the flange portion makes an angle with the base portion. 
     Another embodiment of the present invention discloses a computer enclosure comprising a chassis having a left side, a right side, and a bottom side, wherein a rear edge of the bottom side includes an open hem, a top panel, wherein a rear edge of the top panel includes an open hem, and a rear panel having a left side, a right side, a top side, and a bottom side, wherein the open hem of the bottom side is adapted to receive the bottom side of the rear panel, and the open hem of the top panel is adapted to receive the top side of the rear panel. 
    
    
     BRIEF DESCRIPTION OF THE FIGURES 
     For a more complete understanding of the present invention and for further features and advantages, reference is now made to the following description taken in conjunction with the accompanying drawings, in which: 
     FIG. 1 shows a server in accordance with one embodiment of the present invention. 
     FIG. 2A shows a device and a mounting bracket before the mounting bracket is coupled to the device in accordance with one embodiment of the present invention. 
     FIG. 2B shows the device and the mounting bracket of FIG. 2A after the mounting bracket has been coupled to the device in accordance with one embodiment of the present invention. 
     FIG. 2C shows the device and mounting bracket of FIG. 2B after it has been installed in the server of FIG. 1 in accordance with one embodiment of the present invention. 
     FIG. 2D shows the device and mounting bracket with hole and screw. 
     FIG. 3A illustrates the server of FIG. 1A, and in particular, the design of an interchangeable rear panel in accordance with one embodiment of the present invention. 
     FIG. 3B illustrates a close up view of the left rear corner of the server and the interchangeable rear panel of FIG.  3 A. 
     FIG. 3C illustrates a cross-sectional side view an open hem. 
    
    
     DETAILED DESCRIPTION 
     The preferred embodiments of the present invention and their advantages are best understood by referring to FIGS. 1 through 3 of the drawings. Like numerals are used for like and corresponding parts of the various drawings. 
     FIG. 1 shows a low profile server  50  having multiple components installed therein. For clarity, many of the components shown in FIG. 1 include only simplistic detail, and many of the connections between the various components have been omitted. Server  50  is illustrated with its top panel  130  (shown in FIGS. 3A and 3B) removed. Top panel  130 , however, will generally be mounted to the top of server  50  before server  50  is installed in a server rack. Server  50  includes a unitary chassis having a front side  52 , a right side  54 , a left side  56 , a partial rear side  132 , and a bottom panel  134  (partially shown) opposite top panel  130 . An interchangeable rear panel  58  is shown mounted to the unitary chassis. In the embodiment illustrated, server  50  has a width W of 17.3″, a depth D of 24″, and a standard 1U height H of 1.75″. Interchangeable rear panel  58  includes an exhaust vent  96  and a plurality of input/output ports  94 , which may include serial ports, a console adapter for a keyboard, mouse and/or video, a PCI slot, a PCI expansion slot, an RJ45 Ethernet port, a USB port, etc. A power jack  92  is mounted in partial rear side  132 . 
     Server  50  includes two hard drives  60  and  62  located in the front right portion of server  50 &#39;s chassis. Hard drives  60  and  62  are shown in FIG. 1 as a featureless boxes, but in actuality include various surface features. Hard drives  60  and  62  typically include a sealed aluminum case with an electronic circuit board attached on the bottom. An interface connector (not shown) is provided on the rear portion of hard drives  60  and  62 , and include pins which mate with an interface provided in a hard drive bay (not shown). The height of hard drives  60  and  62  is less than the height H of server  50 , that is, less than 1.75″. In the illustrated embodiment, hard drives  60  and  62  are 1 41   in height and are conventionally mounted between a mounting assembly  90  and right side  54  such that 0.375″ of open space is left between the bottom of hard drives  60  and  62  and bottom panel  134 , and 0.375″ of open space is left between the top of hard drives  60  and  62  and top panel  130 . The open space above and below hard drives  60  and  62  allows ambient air to flow through a mesh or grille (not shown) on the right portion of front side  52  across hard drives  60  and  62  toward the rear portion of server  50 . The flow of air across the top and bottom surfaces of hard drives  60  and  62  cools the hard drives. 
     Located behind hard drive  62  is power supply  64 . Power supply  64  is coupled to and provides power to the electrical components in server  50 . Power supply  64  is also electrically coupled to power jack  92  located in partial rear side  132 . 
     Located behind power supply  64  is a high velocity blower  66 . Blower  66  provides for circulation of and thus cooling of the components within server  50 . Blower  66  may be any type of high velocity blower. Such blowers are often referred to as radial blowers, DC blowers, or centrifugal blowers and have exhaust velocities of ranging from approximately 800-1400 linear feet per minute. In one embodiment, blower  66  is integrated into power supply  64 , but blower  66  can be an independent component. Blower  66  receives air through an inlet vent (not shown) located on the front side  66   a  of blower  66 . The air is then redirected approximately 90 degrees and accelerated by an impeller located within blower  66 . The redirected air then exits through an outlet located on the left side  66   b  of blower  66 . The exhaust exits left side  66   b  of blower  66  at a very high velocity. The movement of air from the front of server  50  into and out of blower  66  is illustrated by the line labeled “FLOW PATH” in FIG.  1 . Blower  66  also includes tab  66   c.  In one embodiment, tab  66   c  is made from a very thin (approximately 0.015″ thick) piece of die cut plastic. Tab  66   c  can also be made from other materials such as spring steel. Tab  66   c  is resiliently mounted to blower  66 . In other words, tab  66   c  can be folded down so that it is flat with the top surface of blower  66 , for example, when top panel  130  is installed onto server  50 . When top panel  130  is removed from server  50 , tab  66   c  flips up. From this position, tab  66   c  and be grasped by a user and thus blower  66  can be removed from server  50 . In the embodiment illustrated, blower  66  is held captive within server  50  by top panel  130 . Thus tab  66   c  is very thin, yet strong enough to allow a user to remove blower  66  from server  50 . 
     Located next to blower  66 , and in particular, next to the exhaust outlet located on left side  66   b  of blower  66 , are two CPUs  68  and  70  having passive heat sinks mounted thereon. CPUs  68  and  70  are mounted to a conventional motherboard  98 . CPUs can be any type of conventional microprocessors such as an Intel Pentium processors. The passive heat sinks mounted on CPUs  68  and  70  include a plurality of conductive heat dissipating prongs that extend away from the CPUs. The air exiting left side  66   b  of blower  66  flows through and across the heat dissipating prongs thereby cooling CPUs  68  and  70 . The air then exits the chassis through exhaust vent  96 . 
     It is important to note that, as mentioned above, conventional server designs included CPUs having heat sinks with fans integrated into the heat sinks. But in conventional low profile server designs, it is very difficult and often impossible to accommodate the height of such CPUs having heat sinks with fans integrated into the heat sinks. Consequently, it was very difficult to adequately cool CPUs in low profile servers. This could lead to impaired performance or complete failure of the CPUs. 
     One advantage of the present invention is that the exhaust outlet of a high velocity blower  66  in placed in close proximity to CPUs  68  and  70 . The exhaust of blower  66  is ducted directly across the passive heat sinks mounted on CPUs  68  and  70 . Since the exhaust of blower  66  is exiting at a high velocity (i.e., approximately 800-1400 linear feet per second), a high convection coefficient is achieved across the passive heat sinks. This convection coefficient is much higher than that which could be achieved using conventional fans used in 1U servers such as 40 mm×40 mm×25 mm fans which produce an exhaust velocities of approximately 200-400 linear feet per second. Thus CPUs  68  and  70  can be adequately cooled in a low profile chassis. 
     Another advantage of the present invention is that it allows CPUs  68  and  70  to remain near rear panel  58  of server  50 . By allowing CPUs  68  and  70  to remain near the rear of the chassis and thus the rear of the motherboard, a server can conform to the well-known ATX specification. 
     Four conventional memory cards  72  are mounted to motherboard  98 . Motherboard  98  contains electrical traces that electrically couple memory cards  72  to CPU&#39;s  68  and  70  which are also mounted to motherboard  98 . Memory cards  72  can include a wide variety of memory devices such as static ram (SRAM) or dynamic ram (DRAM). 
     Expansion component  78  is located adjacent to motherboard  98 . Expansion component can be a PCI card, a network interface card, a SCSI card, etc. 
     Located in front of expansion component  78  is a high velocity blower  76 . Blower  76  can be the same type or a similar type of blower as blower  66  described above. Blower  76  provides for circulation of air and thus cooling of the components within server  50 . Blower  76  receives air through an inlet vent (not shown) located on the front side  76   a  of blower  76 . The air is then accelerated by a impeller located within blower  76  and exits through an outlet located on the rear side  76   b  of blower  76 . The exhaust exits rear side  76   b  of blower  76  at a very high velocity, travels through expansion component  78 , and then exits server  50  through exhaust vent  96  of interchangeable rear panel  58 . Blower  76  also includes tab  76   c  which is similar to tab  66   c  discussed above. 
     Device  74  is located adjacent to front panel  52  so that device  74  can be accessed by a user without having to remove server  50  from the server rack (not shown). For example, if device  74  is a CD ROM, a disk can be installed and removed without having to remove server  50  from the server rack to which it is mounted. In addition to being a CD ROM, device  74  can be a variety of different components such as a digital audio tape (DAT) drive, a slimline combo, etc. In the embodiment illustrated, device  74  is a 5.25″ CD ROM that is 1.62″ in height and 5.75″ wide. 
     Device  74  is mounted within server  50  using a retention clip  100 . FIG. 2A shows device  74  and retention clip  100  before retention clip has been mounted to device  74 . Retention clip  100  includes a base portion  102  having two tabs  106 A and  106 B, and a flange portion  104  having a mounting hole  110 . An angle θ, which is approximately 90 degrees, is formed between flange portion  104  and base portion  102 . Tabs  106 A and  106 B can be sheet metal tabs which are formed by bending two small pieces of metal from base portion  102 . To mount retention clip  100  to device  74 , mounting bracket  100  is placed against the side of device  74  aligning tabs  106 A and  106 B with corresponding mounting holes  108 A and  108 B on device  74 . Tabs  106 A and  106 B are then placed through mounting holes  106 A and  106 B where they lock into place. In an alternative embodiment, tabs  106 A and  106 B could be holes, and screws or other fasteners could placed through the holes and then fastened into mounting holes  108 A and  108 B using conventional tools. FIG. 2B shows device  74  after retention clip  100  has been mounted. 
     After retention clip  100  has been secured to device  74 , device  74  can be mounted within server  50 . To mount device  74  within server  50 , a user first removes top panel  130  of server  50 . Device  74  is then placed on the bottom panel  134  of server  50  while aligning mounting hole  110  of retention clip  100  with a mounting hole  122  of a mounting bracket  112  as shown in FIG. 2D. A thumb screw  124  is then used to secure retention clip  100  (and thus device  74 ) to mounting bracket  112  (and thus bottom panel  134  of the server chassis). Thumb screw  124  can then tightened by a user without the use of tools thereby securing device  74  within server  50 . FIG. 1 illustrates device  74  after it has been mounted within server  50 . In the embodiment illustrated, device  74  is secured within server  50  entirely by retention clip  100 . In other embodiments, device  74  can also be secured by an angle bracket/ledge which is placed between hard drives  60  and  62  and the right side of device  74 . Such an angle bracket/ledge will further secure device  74  and prevent it from sliding toward hard drives  60  and  62 . 
     FIG. 2C shows mounting bracket  112  is greater detail. Mounting bracket  112  includes a base portion  114  having two mounting holes  120 A and  120 B, a first flange  116 , and a second flange  118  having a mounting hole  122 . Mounting bracket  112  is secured to the bottom panel  134  of server  50  by placing screws or other fasteners (not shown) through mounting holes  120 A and  120 B and then fastening the screws or other fasteners into corresponding mounting holes (not shown) in the bottom panel  134  of server  50 . Mounting bracket  112  can also be mounted to the bottom panel  134  of server  50  by a spotweld. Mounting bracket  112  is typically secured to the bottom panel  134  of server  50  before device  74  is secured to mounting bracket  112 . 
     It is important to note that, in conventional server designs, devices such as device  74  were mounted using the eight mounting holes provided on the two sides of device  74  (i.e., mounting holes  108 A,  108 B,  109 A, and  109 B and four similar mounting holes (not shown) located on the right side of device  74 ). This made the installation and removal of such devices very difficult. For example, if device  74  of FIG. 1 needed to be removed from server  50 , hard drives  60  and  62  and blower  76  would have to be removed first so that a user could access the four screws on the left side of device  74  and the four screws on the right side of device  74 . This process is extremely time consuming and cumbersome and could potentially lead to damage of hard drives  60  and  62  or other components due to excessive handling. 
     One advantage of the present invention is that retention clip  100  (and thus device  74 ) can be mounted to server  50  using a single thumb screw  124  providing for easy installation an removal of device  74 . Thumb screw  124  can be tightened by a user without the use of tools. This allows a user to install or remove device  74  very easily. Neither hard drives  60  and  62 , blower  74 , nor any other components that may be close to device  74  need to be removed to install or remove device  74 . 
     FIG. 3A illustrates server  50 , and in particular, the design of interchangeable rear panel  58 . For clarity, the components typically residing in server  50  are not shown in FIG.  3 A. As described above, server  50  includes a unitary chassis having front side  52 , right side  54 , left side  56 , partial rear side  132 , and bottom side  134  (partially shown) opposite top panel  130 . Server  50  also includes interchangeable rear panel  58  which can be mounted to the unitary chassis. 
     Interchangeable rear panel  58  includes exhaust vent  96  and a plurality of input/output ports  94 , which may include serial ports, a console adapter for a keyboard, mouse and/or video, a PCI slot, a PCI expansion slot, an RJ45 Ethernet port, a USB port, etc. Partial rear side  132  includes a hole for receiving power jack  92  (FIG.  1 ). Partial rear side  132  also includes a mounting hole  140  which aligns with a corresponding mounting hole  142  on rear panel  58 . Left side  56  includes a mounting hole  136  which aligns with a corresponding mounting hole  138  on rear panel  58 . Bottom side  134  includes an open hem  150 . Top panel  130  includes an open hem  152 . 
     FIG. 3B shows a close up view of the left rear corner of server  50  and rear panel  58 . Open hems  150  and  152  include openings  150 A and  152 A. Openings  150 A and  152 A are adapted to receive bottom side  58 A and top side  58 B, respectively, of rear panel  58 . FIG. 3C shows a cross-sectional side view of open hem  150  and opening  150 A. 
     Rear panel  58  can be installed into server  50  as follows. Rear panel  58  is placed against bottom side  150  approximately one inch away from open hem  150 . Rear panel is then slid toward open hem  150  as indicated by arrow  160 . Bottom side  58 A of rear panel then slides into opening  150 A of open hem  150  and is held in place by frictional forces created by the coupling of open hem  150  and bottom side  58 A. Top panel  130  is installed in a similar manner as indicated by arrow  162 . Top side  58 B of rear panel is held in place by frictional forces created by the coupling of open hem  152  and top side  58 B. 
     The frictional forces created between open hem  150  and bottom side  58 A of rear panel and open hem  152  and top side  58 B of rear panel are strong enough to secure rear panel in server  50 . However, mounting holes  138  and  142  are provided on each side of rear panel  58  to further secure rear panel in server  50 . Mounting hole  138  aligns with mounting hole  136  of left side  56  and mounting hole  142  aligns with mounting hole  140  of partial rear side  132 . Screws or other fasteners can then placed through and tightened in these mounting holes to further secure rear panel  58  to the server&#39;s chassis. 
     One advantage of the present invention, and in particular the open hem design described with reference to FIGS. 3A-3C, is its structural integrity. Those skilled in the art will recognize that the coupling of open hem  150 , which is integrally connected with the bottom side  134  of the server, with bottom side  58 A of the rear panel creates a unitary structural member that is very stiff. Likewise, the coupling of open hem  152  with top side  58 B of the rear panel creates a unitary structural member that is very stiff. Another advantage of the present invention that it allows for the rear panel to be changed relatively easily, while maintaining structural integrity of the chassis. This is advantageous since it allows multiple motherboards (which can be attached to the rear panel) to be used with a single chassis. Further, interchangeable rear panels are relatively inexpensive to design and manufacture. Thus, a custom server can be designed quickly and inexpensively while maintaining the structural integrity of the server chassis. 
     Yet another advantage of the present invention is that the mating of the open hem of the bottom side of the chassis with the bottom side of the rear panel, and the mating of the open hem of the top panel with the top side of the rear panel provides for a strong electromagnetic radiation shield. This is especially important as the speeds of CPUs increase and generate more electromagnetic energy which can radiate out of the server and interfere with neighboring servers. 
     While particular embodiments have been shown and described, it will be obvious to those skilled in the art that various changes and modifications may be made without departing from this invention in its broader aspects and therefore the appended claims encompass all such changes and modifications as fall within the true spirit and scope of this invention.