In a computer system that utilizes upstream fans for cooling, a pressurized volume of air is directed towards the downstream components. Imbalances in airflow impedance in the downstream area can cause the airflow to bypass critical components. Some printed circuit (PC) assemblies have optional components. When the optional components are missing from the PC assemblies, gaps or open/empty regions are created in the airflow path. The gaps or open/empty regions create imbalances in airflow impedance across the PC assembly. The air tends to flow into the gaps or open/empty region and can cause the airflow to bypass critical components.
One type of PC assembly that has optional components is the memory boards in computer systems. A primary memory boards may have a number of slots available for the installation of optional printed circuit assembly such as a dual in-line memory module (DIMM). Typically the DIMMs are vertically installed into the open slots in the primary memory board. In some configurations all the slots in the primary memory board may not be filled. These empty slots create gaps or open/empty regions in the assembly. Air flowing through the assembly tends to flow into and through these gaps, thereby reducing the amount of air flowing past the slots with DIMMs installed.
Currently there are two general solutions to this problem. One solution is to install non-functional “dummy” DIMMs into each unoccupied DIMM slot. This adds extra cost for each of the dummy printed circuit board (PCB) components. Using dummy DIMMs also requires that a human operator guarantee that dummy DIMMs are installed in all slots not occupied by real DIMMs. In the event that a dummy DIMM is left uninstalled, air bypass is encountered which can contribute to overheating of the installed DIMMs. Electronic methods of sensing the presence of real or dummy DIMMs can be implemented to detect any empty slots. This adds additional cost to the device. The cost increase is for the electronic components used to detect the empty slots as well as the cost for dummy DIMMs. Dummy DIMMs can get lost or thrown away in the process of updating DIMMs in a computer system over time. In the event that a working DIMM is removed from a system, a dummy DIMM to replace it with may not be available to the operator.
A second solution is to install a removable baffle above the entire array of DIMMs. The baffle does not fill any unoccupied slots. The baffle simply fills the physical volume directly above a full bank of DIMMs and forces air down into the DIMM array. As such, any non-occupied DIMMs do present a low impedance area where air can escape without properly cooling the installed and adjacent DIMMs. To compensate for this effect, upstream fans are typically located closer to the DIMMs and the velocity stream of the air pushes the air into the entire array of DIMMs, even when empty slots are encountered. In cases where the fans cannot be located in close proximity to the DIMMs, the only solution may be to use dummy DIMMs.
During normal operation, air is forced into memory board assembly 100 as indicated by arrows 110. Empty connector 106 creates a gap or open/empty region 112 in the memory board assembly 100. The gap or open/empty region 112 creates an imbalance in airflow impedance across memory board assembly 100. Air flowing in the direction of arrows 110 may flow into gap or open/empty region 112 thereby reducing the air flow across the plurality of secondary memory boards 108.
In one example embodiment of the invention, gaps may be located between the blocking fingers 226 (as shown in
In one example embodiment of the invention, torsion springs may be incorporated into hinges 228. In another example embodiment of the invention, torsion springs may be mounted beside hinges 228. In another example embodiment of the invention, compression springs may be used to force blocking fingers in the direction away from plate 222.
In one example embodiment of the invention, air flow redirection device 200 may be mounted onto a printed circuit board (PCB), for example primary memory board 102. In another example embodiment of the invention, air flow redirection device 200 may be part of a rack that is configured to have PC assemblies installed into slots or mounting systems in the rack. In another embodiment of the invention, plate 222 may be incorporated into a top cover of a PCB sheet metal tray/enclosure. In this case the PCB mounts to a metal tray/pan, and a removable top cover is installed vertically onto the PCB+tray assembly. As the cover is installed down onto the board, the blocking fingers rotate off any installed DIMMs, or insert into the non-occupied DIMM slots. In this example embodiment of the invention, the air flow redirection device is installed into the closed position using a translation instead of a rotation.
In operation, frame 220 is aligned with PC assembly 100 with the primary hinge 224 located near the ends of, and perpendicular to, the connectors 104 on PC assembly 100. Plate 222 is rotated away from frame 220 into the open position, allowing secondary memory boards 108 to be loaded into connectors 104. Once all the secondary memory boards 108 are loaded into connectors 104, plate 222 is rotated into the closed position on top of frame 220. Locking features 236 hold plate 222 into the closed position. Spring loaded blocking fingers 226 will contact the top of the installed secondary memory boards 108, and be forced towards plate 222. Spring loaded blocking fingers 226 that are aligned with a connector that is empty will be swung down into the gap or empty/open space created by the empty connector in PC assembly 100. The blocking fingers aligned with empty connectors block air flowing in the direction of arrows 110, and force the air between the installed secondary memory boards 108.
In one embodiment of the invention, locking features 236 may be screws or other fasteners that require tools. In another example embodiment of the invention, locking features 236 may be configured to activate without the use of tools, for example flexible tabs that snap into place, spring loaded pins that snap into place, or the like.
Because spring loaded blocking fingers 226 automatically block gaps or empty/open spaces created by empty connectors, dummy DIMMs or additional ducting is not required. In one example embodiment of the invention, the installation of the PC assembly 100 can not be completed when plate 222 is left in the open position. This ensures that plate 222 is located in the closed position with blocking fingers 226 swung into any open spaces when PC assembly is completely installed.
The example above has DIMMs as the optional components in the PC assembly. This invention is not limited to DIMMs but may be used with any optional component in a PC assembly.