Abstract:
In general, in one aspect, the disclosure describes an apparatus to redistribute airflow throw slots of a chassis that houses boards. The apparatus includes at least one restriction region to limit airflow therethrough. The apparatus further includes an open region to allow airflow to pass therethrough. At least some of the airflow limited by the at least one restriction region will flow through the open region. The apparatus also includes a connection mechanism to connect to a chassis.

Description:
BACKGROUND  
       [0001]     Modular computing systems contain many boards and/or interconnects (hereinafter referred to as “boards”) that can be easily inserted and removed from a rack (chassis). These systems provide large amounts of processing in a small environment. The boards within the rack will require cooling. High processing components on the boards will generate the most heat and will require the most cooling. As the modular computing systems are tightly bundled the effectiveness of heat sink technology is limited by the limited space available. The chassis&#39; will be designed to provide airflow for cooling of components.  
         [0002]     The chassis&#39; are often governed by standards, such as the PCI Industrial Computer Manufacturers Group (PICMG), Advanced Telecommunications Computing Architecture (ATCA) Base Specification, PIGMG 3.0 Revision 1.0, published Dec. 30, 2002 (hereinafter referred to as “the ATCA specification”). Accordingly, the airflow design of the chassis may not be optimized for any particular use. Accordingly, the airflow may not be efficient for particular boards. Furthermore, the airflow through the slots may not be evenly distributed. Moreover, as the processing power of the boards and the associated heat generation of the boards increases, the chassis may not provide sufficient airflow to provide cooling for these heat generating components.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0003]     The features and advantages of the various embodiments will become apparent from the following detailed description in which:  
         [0004]      FIG. 1  illustrates a perspective view of an example chassis (rack), according to one embodiment;  
         [0005]      FIG. 2  illustrates a cross-sectional side view of an example chassis and typical airflow pattern thereof, according to one embodiment;  
         [0006]      FIG. 3  illustrates an example baffle, according to one embodiment;  
         [0007]      FIG. 4  illustrates example airflows with and without a baffle, according to one embodiment;  
         [0008]      FIG. 5  illustrates an example baffle installed in a chassis, according to one embodiment; and  
         [0009]      FIG. 6  illustrates a cross-sectional side view of an example chassis and baffle and improved airflow distribution, according to one embodiment.  
     
    
     DETAILED DESCRIPTION  
       [0010]      FIG. 1  illustrates a perspective view of an example chassis (rack)  100  for use with embedded computer systems. The chassis  100  includes a housing  110  (e.g., outer shell, walls) and a frame  120  for holding boards  130  (e.g., ATCA blades). Only a single board  130  is illustrated installed in the frame  120  and no components are illustrated on the board  130  for simplicity. The frame  120  consists of upper and lower rails  140  (guide rails) that guide the boards into the housing  110 . It should be noted that only the lower rails  140  are visible in  FIG. 1 . As illustrated, the boards  130  reside vertically in the chassis  100 . A back edge (not illustrated) of the boards  130  may plug into adapters (not illustrated) in the chassis  100 . The adapters may enable the boards  130  within the chassis  100  to communicate with one anther and/or may enable the boards  130  to communicate external to the chassis  100  (with other computers or systems).  
         [0011]     The chassis  100  may be a governed by standards (e.g., the ATCA specification). The standards may control, the size of the chassis, the number of slots (shelves) in the chassis, the cooling provided by the chassis, where the components are placed on the boards, electrostatic discharge (ESD) parameters, as well as other aspects. For example, the ATCA specification requires that each slot (shelf) have an ESD wrist strap terminal on the front of the slot and that the terminal be unpainted.  
         [0012]     The example chassis  100  illustrated is based on the ATCA specification. The various embodiments illustrated herein will be based on the ACTA chassis. However, this is in no way intended to limit the scope of the various embodiments to a chassis based on the ACTA specification. In fact, the various embodiments described herein need not be limited to chassis&#39; governed by standards, chassis&#39; that insert boards vertically, or chassis&#39; that support specific board types. Rather, the various embodiments described herein could be applied to any type of chassis for holding equipment (e.g., electronic equipment) that requires cooling.  
         [0013]      FIG. 2  illustrates a side view of an example chassis  200 . The chassis includes upper guide rails  210  and lower guide rails  220 . Between the guide rails  210 ,  220  boards (e.g., ATCA blades)  230  are installed vertically. Only a single board  230  having several components mounted thereon is visible but multiple boards  230  are likely included in the chassis  200 . Behind the boards  230  is an interface area  240  (no interface equipment is illustrated). The interface area  240  may house a backplane to provide connectivity between the boards  230  and power to the boards  230 . In addition, the interface area  240  may include transmission modules that provide connectivity between the boards  230  and external sources. The interface area  240  may have guide rails  250  for supporting the interface equipment. Below the boards  230  is an open space (lower open space)  260  and above the boards  230  is open space (upper open space)  270 . At one end of the upper open space (e.g., rear) is a fan (or fans)  280 . The fan  280  and the upper and lower open spaces  260 ,  270  may act as an air flow system. The air flow system may pull air through the chassis  200  (up from the lower open space  260  across the boards  230  to the upper open space  270 ). Pulling the air through the chassis  200  may cool the boards  230  inserted in the chassis  200 .  
         [0014]     Airflow through the chassis  200  and across the boards  230  in the chassis  200  may or may not be evenly dispersed. For example, the airflow through the chassis  200  may tend to be strongest in the center and weaker towards the edges of a board  230  as indicated by the arrows (larger arrows indicating more air flow). Such an airflow pattern means that components on the center of the board  230  will be cooled more then components on the edges of the board  230 . Depending on the placement of components on the board  230 , this type of airflow may or may not be efficient and/or sufficient. That is, if the components creating the most heat are located in the region receiving the most airflow then passing the most air over this portion would be preferable. However, the components generating the most heat are not always placed in the center of the board  230 . For some board designs the heat generating components may be best placed on an edge of the board  230  for communications with other boards or other devices.  
         [0015]     An important aspect of the airflow through the chassis is the chassis design. That is, the chassis design may play a role in or dictate the average maximum airflow that is possible through the chassis. As the airflow may not be evenly distributed, it is possible that the chassis will not be able to provide an acceptable airflow for heat generating components that are not placed in the strongest airflow regions of the board (e.g., center). That is, if the average maximum airflow attainable is 500 linear feet per minute (LFM) the airflow may be distributed in such a way that 550 LFM is attained at the center and only 450 LFM is attainable at the edges. If a component (or components) generating a large amount of heat is located on the side of the board and needs an airflow of 500 LFM to keep the component (or components) cool, the chassis may be not able to support that configuration.  
         [0016]     Alternatively, increasing the airflow for components not aligned with the most efficient air flow portion of the board (e.g., center) may result in excess cooling taking place at the most efficient portion. For example, if an airflow of 500 LFM was required for a heat generating component (or components) that were located on the edge of the board may result in an airflow of 600 LFM at the center of the board which may not have any heat generating components or may need much less airflow.  
         [0017]     The airflow through the chassis needs to be controlled or diverted (e.g., improved) so that the most airflow is directed to the area on the board having the most heat generation. Improving the airflow would enable components to be placed on the board based on operational factors not heating issues. One possible way to improve the airflow is by restricting the airflow to portions of the board that do not need as much airflow and accordingly increasing the airflow to other portions that need more airflow. A baffle could be used to control the airflow over a board.  
         [0018]      FIG. 3  illustrates an example baffle  300  that could be used to control the airflow through a chassis (e.g., chassis  100 ,  200 ). The baffle  300  includes openings of varying sizes. The biggest opening allowing the most air to flow and the smallest opening restricting the most airflow. Using the baffle  300  redirects some of the airflow from the more restricted areas to the less restricted areas as air flow will tend to move to the path of least resistance.  
         [0019]     The example baffle  300  has three distinct regions of air restriction to control airflow. A first region  310  consists of a plurality of small holes. The small holes would provide the most restriction to the airflow as the air would need to be pulled through these small holes. A second region  320  consists of a plurality of medium size holes that would restrict airflow but not to the extent that airflow would be restricted by the first region  310 . A third region  330  consists of an opening that provides little or no resistance to the flow of air. The air being restricted from the first and the second regions  310 ,  320  (restricted regions) may be redirected to the third region  330  (open region). Accordingly, the airflow through the third region  330  may be increased while the airflow through the first and second regions  310 ,  320  may be decreased. It should be noted that the baffle  300  is in no way limited to the illustrated embodiment. Rather, any number of configurations and any number of different regions can be used with departing from the scope of the various embodiments described herein.  
         [0020]      FIG. 4  illustrates example airflows with no baffle and utilizing a baffle. The example airflow  400  with no baffle is strongest in the center  410  and tapers off toward the edges  420 . For example, if the average airflow through the chassis  400  is 500 LFM then the center airflow  410  may be 550 LFM and the edge airflow  420  may be 450 LFM. The example airflow  430  is controlled by the baffle  440 . The baffle  440  has three distinct restriction regions. A first region  450  has a plurality of medium size holes for medium restriction. A second region  460  has a plurality of small holes for substantial restriction. A third region  470  is a large opening for minimal or no restriction. The airflow through the baffle  440  is greatest where there is least restriction and least where there is the most restriction. For example, if the average chassis airflow  430  is 500 LFM then the airflow  480  associated with the first region  450  may also be 500 LFM (compared to the 450 LFM airflow  420  with no baffle). The airflow  485  associated with the second region  460  may be 400 LFM (compared to the 550 LFM center airflow  410  with no baffle). The airflow  490  associated with the third region  470  may be 600 LFM (compared to the 450 LFM edge airflow  420  with no baffle).  
         [0021]     As noted above, the airflow rate through the chassis and the slots within the chassis can be considered constant. The baffle takes advantage of the relatively constant airflow rate provided by the chassis to alter the airflow resistance across the slots without impacting the overall chassis airflow performance. The baffle&#39;s free area ratio (or vent hole size and location) across the slot can be tailored to improve the local airflow velocity for components that need it most. The baffle diverts the airflow to prescribed area needing the most airflow. The end result of using the baffle is improved airflow in the chassis to increase the cooling capacity for the board (e.g., ATCA blade).  
         [0022]     The example baffles  300 ,  400  of  FIGS. 3 and 4  consist of three distinct regions and the regions that restrict airflow consist of a plurality of holes. However, the baffle is in no way limited thereby. The baffle could have as many distinct regions as desired. For example, a baffle could have a single open portion to force all the airflow to that portion or could have five distinct portions to provide five airflow patterns across the board. The restrictive portions could be any assortment of holes, lines, patterns that provide various levels of restriction. For example, a restrictive portion could be a plurality of thin lines while a moderate restriction could be a plurality of moderate sized lines.  
         [0023]     Referring back to  FIG. 3 , the various regions  310 ,  320 ,  330  may correspond to the components on the board and their need for cooling. Components needing the least cooling may be aligned with the first region  310  (most restricted region), components needing intermediate cooling may be aligned with the second region  320 , and components needing the most cooling are aligned with the third region  330  (least restricted region). Aligning the regions of the baffle  300  with the associated cooling requirements of components on the board provides the most efficient use of airflow. Using the baffle  300  in the chassis (e.g., chassis  100 ,  200 ) may modify the airflow and accordingly improve the cooling capacity for high heat generating components placed on the boards inserted in the chassis.  
         [0024]     The baffle  300  modifies the airflow resistance across the slot and forces air to flow through the paths of least resistance. The baffle  300  extends the cooling capacity of processors and chipsets particularly in confined spaces (e.g., ATCA blades). The baffle  300  reduces the dependence of component placement, particularly with high heat generating components (e.g., processors). The baffle  300  takes advantage of the relatively constant airflow rate provided by the chassis (e.g., ATCA chassis) to alter the airflow resistance across the slot thus improving the local airflow rate where desired.  
         [0025]     Managing the local airflow rate using the baffle  300  allows a board (e.g., ATCA blade) designer to place components where they are better suited for layout and routing conditions (which typically conflict with thermal placement of components). Combined with thermal placement of components, the baffle  300  may further improve the cooling limits. The increased cooling limits may increase the computing density capacity of the boards (e.g., ATCA blades) and/or enable the use of even higher performance (and accordingly higher heat generation) processors and chipsets.  
         [0026]     According to one embodiment, the baffle  300  may be produced for the specific board so as to optimize airflow per board based on placement of the heat generating components on the board. Designing the baffle  300  to the specific board provides the most flexibility in board design as placement of the components on the board based on heat generation will not be as much of a factor. The baffle  300  may be sold with the board and/or may be sold as an accessory to the board.  
         [0027]     According to one embodiment, the baffles may be designed in a plurality of styles to fit different board types. For example, one baffle type may improve the airflow to the front of the board while another baffle may improve the airflow to the back of the board. When boards are being designed they can be designed taking into account the various baffle styles. The standard baffle types may provide a board designer with flexibility in the design of the board to account for heat generation as there may be various heat dissipation options available.  
         [0028]     The baffle  300  may be made of a light weight material (e.g., plastic). The baffle may be made using a typical low cost manufacturing processes (e.g., plastic injection molding). However, the baffle is not limited to the type of material or to the process of making. Rather, the baffle could be made of any material that could provide the airflow improvements without departing from the scope of the various embodiments described herein.  
         [0029]     The baffle  300  may also include a connection device  340  to enable the baffle to be connected in the chassis. According to one embodiment, the baffle  300  is connected to the lower guide rails (e.g.,  140 ,  220 ). Connecting the baffle to the guide rails instead of the board allows the board and the baffle to be installed without interfering with the chassis during installation of the board in the slot. According to one embodiment, the connection device  340  provides a removable rather then permanent connection to the chassis. The connection device  340  may be any type of apparatus (e.g., clip, hook, latch) that would provide a removable secure connection to the guide rails. The connection device  340  may be located on the short edges of the baffle that correspond to the front and back of the slot. The baffle  300  is not limited in the location of the connection device or the number of connection devices. As illustrated, the connection device  340  is a J-clip that extends vertically up from the baffle and then extends diagonally downward and outward. The connection device may be flexible so that it can be inserted in the rails and then will lock into the lower guide rails.  
         [0030]      FIG. 5  illustrates an example chassis  500  having an example baffle  510  installed therein. The baffle  510  is connected to a lower guide rail  520  of the chassis. The baffle  510  is removably connected to the front and back of the slot and the lower guide rail  520  utilizing a clip  530  (e.g., connecting mechanism  340 ) on the baffle  510 . The clip  530  connects the baffle to the lower guide rail  520  at the front and back of the slot. The clip  530  extends up through the lower guide rail  520  and then extends over a portion of the lower guide rail  520  to hold the baffle  510  in place. As previously discussed, the baffle  510  restricts and focuses airflow over the board with which it is associated. A different type of baffle could be connected to each lower guide rail associated with each board so as to affect airflow in a different way that is consistent with the make up of the board.  
         [0031]      FIG. 6  illustrates an example chassis  600  (e.g., chassis  200  of  FIG. 2 ) with an example baffle  610  installed on a lower guide rail  620 . The baffle  610  improves the airflow through the particular slot so that the airflow is more suited for the particular board installed therein. In this case, the airflow has increased over the back of the board where heat generating components  630  are located as indicated by the larger arrows.  
         [0032]     While the baffle has been discussed above with specific emphasis on ATCA chassis&#39; and boards, the baffle is not limited thereby. Rather, the baffle can be applied to other modular computing form factors. The baffle is also not limited to boards containing processors as the heat generating device, but is applicable to other components as well. The baffle can be used for cooling any heat generating components.  
         [0033]     Although the various embodiments have been illustrated by reference to specific embodiments, it will be apparent that various changes and modifications may be made. Reference to “one embodiment” or “an embodiment” means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, the appearances of the phrase “in one embodiment” or “in an embodiment” appearing in various places throughout the specification are not necessarily all referring to the same embodiment.  
         [0034]     The various embodiments are intended to be protected broadly within the spirit and scope of the appended claims.