Patent Publication Number: US-2023160485-A1

Title: Backflow blocking device for axial fans

Description:
TECHNICAL FIELD 
     The present disclosure relates generally to blocking air backflow with a device on a fan. 
     BACKGROUND 
     There are a variety of rack mount enclosures currently available that draw external ambient air from the front of the enclosure, pass the air through the enclosure, and exhaust the air through the rear of the enclosure. As the moving air passes by operating circuits within the enclosure, the air carries away heat from the operating circuits thus maintaining the operating circuits within a normal operating temperature range for proper operation and reliability. 
     One conventional rack mount enclosure is 1 U (approximately 1.75 inches) in height and includes a fan assembly configured as a field replaceable unit (FRU). The fan assembly includes a fan frame and a row of four fans fastened to the fan frame. The fan frame includes a vertical face plate which faces outwardly from the front of the enclosure and two thumbscrews secured to the vertical face plate. The vertical face plate and the thumbscrews are offset from the profiles of the four fans in order to avoid obstructing the airflow generated by the fans. The thumbscrews thread into thumbscrew holes defined by the enclosure thus holding the frame to the enclosure to prevent the fan assembly from inadvertently escaping (e.g., due to vibration). 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
       The accompanying drawings, which are incorporated in and constitute a part of this disclosure, illustrate various embodiments of the present disclosure. In the drawings: 
         FIG.  1 A  and  FIG.  1 B  show a top view of an electronic device; 
         FIG.  2 A ,  FIG.  2 B , and  FIG.  2 C  show various views of a backflow blocking apparatus; 
         FIG.  3 A  and  FIG.  3 B  show a backflow blocking apparatus; and 
         FIG.  4    is a flow chart setting forth the general stages involved in a method for providing a backflow blocking apparatus. 
     
    
    
     DETAILED DESCRIPTION 
     Overview 
     A backflow blocking apparatus for axial fans may be provided. The apparatus may comprise a sheet. The sheet may comprise a first section and a second section. The first section may comprise a plurality of flaps cut out of and retained by the first section of the sheet. The second section may comprise a guard structure. The apparatus may further comprise a fold about which the first section and the second section are folded on one another. The guard structure may inhibit the movement of the plurality of flaps in a direction toward the guard structure when the first section and the second section are folded on one another. 
     Both the foregoing overview and the following example embodiments are examples and explanatory only and should not be considered to restrict the disclosure&#39;s scope, as described and claimed. Furthermore, features and/or variations may be provided in addition to those described. For example, embodiments of the disclosure may be directed to various feature combinations and sub-combinations described in the example embodiments. 
     Example Embodiments 
     The following detailed description refers to the accompanying drawings. Wherever possible, the same reference numbers are used in the drawings and the following description to refer to the same or similar elements. While embodiments of the disclosure may be described, modifications, adaptations, and other implementations are possible. For example, substitutions, additions, or modifications may be made to the elements illustrated in the drawings, and the methods described herein may be modified by substituting, reordering, or adding stages to the disclosed methods. Accordingly, the following detailed description does not limit the disclosure. Instead, the proper scope of the disclosure is defined by the appended claims. 
     Axial fans may be used to cool components in an electronic device. From time-to-time some of these fans may fail. When a fan fails and other fans are still operating, an airflow recirculation or backflow may occur. In other words, when axial fans are installed in parallel and one them fails, the other working fans pull air back through the failed fan creating a backflow. Airflow recirculation or backflow through a failed fan may be a significant problem that may result in higher or failing component temperatures. For example, the backflow through the failed fan may result in less airflow being pulled through the system and higher component temperatures. 
     Consistent with embodiments of the disclosure, blocking or partially blocking the air path when a fan fails may provide a cost-effective solution. For example, a backflow blocking apparatus made of a folded sheet may be attached to a fan exhaust. The backflow blocking apparatus may comprise, for example, a thin plastic part that may be cut in pieces to create flaps. The apparatus may then be installed at an axial fan&#39;s exhaust. When the fan is on and pulling airflow, the flaps may open to allow normal operation of the fans. Should the fan fail, the flaps may fall in place and block the airflow from flowing back through the failed fan in the opposite orientation. Embodiments of the disclosure may be cost effective because it may comprise one plastic part instead of a complex array of mechanical louvers. 
       FIG.  1 A  and  FIG.  1 B  show a top view of an electronic device  100 . As shown in  FIG.  1 A  and  FIG.  1 B , electronic device  100  may comprise a plurality of fans  102  and electronic components  104 . Plurality of fans  102  may comprise a first fan  106 , a second fan  108 , and a third fan  110 . First fan  106  may comprise a first fan exhaust  112 , second fan  108  may comprise a second fan exhaust  114 , and third fan  110  may comprise a third fan exhaust  116 . 
     Electronic device  100  may comprise a line card that may comprise any modular electronic component, field replaceable unit, service card, line card, fabric card, or other card, component, or module configured for insertion and removal from a network device. For example, electronic device  100  may comprise, but is not limited to, a fabric card, a service card, a combo card, a controller card, a processor card, a high density line card, and a high power line card. Notwithstanding electronic device  100  may comprise many types of field replaceable electronic units that may slide in or out of a chassis. 
     As shown in  FIG.  1 A , first fan  106 , second fan  108 , and third fan  110  may be running and may pull air over electronic components  104  in order to cool them. Plurality of fans  102  in  FIG.  1 A  may be running at less than 100% and may be cooling electronic components  104  sufficiently. However, as shown in  FIG.  1 B , third fan  110  may fail. In response, a controller of first fan  106  and second fan  108  may cause first fan  106  and second fan  108  to run at 100% of their capacity. 
     When third fan  110  fails, and first fan  106  and second fan  108  are still operating, an airflow recirculation or backflow may occur. In other words, when plurality of fans  102  are installed in parallel and third fan  110  fails, first fan  106  and second fan  108  may pull air back through third fan  110  creating the backflow. The backflow through third fan  110  may be a significant problem that may result in higher or failing temperatures for electronic components  104 . 
     Consistent with embodiments of the disclosure, a backflow blocking apparatus made of a folded sheet may be attached to respective exhausts (i.e., first fan exhaust  112 , second fan exhaust  114 , and third fan exhaust  116 ) on each of first fan  106 , second fan  108 , and third fan  110 . The backflow blocking apparatus may comprise, for example, a thin plastic part that may be cut in pieces to create flaps. When first fan  106 , second fan  108 , and third fan  110  are on and pulling airflow, the flaps may open on each of their respective backflow blocking apparatuses to allow normal operation of the fans. However, when third fan  110  fails, the flaps on the backflow blocking apparatus on third fan exhaust  116  may fall in place and block the airflow from flowing back through failed third fan  110  in the opposite orientation. 
       FIG.  2 A ,  FIG.  2 B , and  FIG.  2 C  show various views of a backflow blocking apparatus  200 . As shown in  FIG.  2 A , backflow blocking apparatus  200  may comprise a sheet  202  comprising a first section  204 , a second section  206 , and a fold  208 . 
     First section  204  may comprise a plurality of flaps  210  a plurality of retention members  212 , a plurality of first section sides  214 , and a plurality of fasten openings  216 . Plurality of flaps  210  may comprise a first flap  218 , a second flap  220 , a third flap  222 , a fourth flap  224 , and a fifth flap  226 . While  FIG.  2 A  shows five flaps, embodiments of the disclosure may comprise any number of flaps and is not limited to five. Plurality of retention members  212  may comprise a first retention member  228 , a second retention member  230 , a third retention member  232 , a fourth retention member  234 , and a fifth retention member  236 . 
     Second section  206  may comprise a guard structure  238  and a plurality of second section sides  240 . Guard structure  238  may comprise a first plurality of cross members  242 , a second plurality of cross members  244 , and a plurality of openings  246 . First plurality of cross members  242  may be periductular to second plurality of cross members  244 . Plurality of openings  246  may be any shape including, for example, rectangular. Plurality of openings  246  may be punched out of second section  206  of sheet  202 . 
     Plurality of flaps  210  may be created by cutting a respective and associated plurality of slits  248  in first section  204 . Plurality of flaps  210  may be retained by the respective and associated plurality of retention members  212 . As shown in  FIG.  2 B  and  FIG.  2 C , first section  204  and second section  206  may be folded on one another about fold  208 . Guard structure  238  may inhibit the movement of plurality of flaps  210  in a direction toward guard structure  238  when first section  204  and second section  206  are folded on one another. Plurality of flaps  210  may be retained by the respective and associated plurality of retention members  212  when each of plurality of flaps  210  rotate between an open position and a closed position. Plurality of flaps may comprise any shape including, for example, triangular. 
     First section  204  of sheet  202  and second section  206  of sheet  202  may comprise a same size and a same shape. Furthermore, plurality of first section sides  214  of first section  204  may comprises a same length and plurality of second section sides  240  of second section  206  may have this same length. Plurality of fasten openings  216  may receive fasteners that may be used to attach backflow blocking apparatus  200  to an exhaust of an axial fan when first section  204  and second section  206  are folded on one another. The axial fan may comprise a 40 mm by 40 mm axial fan. 
     In some embodiments, sheet  202  may comprises a thickness of between 0.004 inches and 0.006 inches. In other embodiments, sheet  202  may comprises a thickness of between 0.0085 inches and 0.013 inches. Sheet  202  may comprise flame retardant polypropylene. For example, sheet  202  may comprise the GK flame retardant polypropylene sheet (e.g., GK-5 or GK-10) produced by ITW Electronic Components FORMEX of 425 North Gary Ave. Carol Stream, Ill. 60188. 
       FIG.  3 A  and  FIG.  3 B  show backflow blocking apparatus  200  with plurality of flaps  210  in an open position. As stated above, backflow blocking apparatus  200  may be installed at the exhaust of an axial fan. When the fan is on and pulling airflow, plurality of flaps  210  may open to allow normal operation of the fans. Should the fan fail, plurality of flaps  210  may fall in place and block the airflow from flowing back through the failed fan in the opposite orientation. 
       FIG.  4    is a flow chart setting forth the general stages involved in a method  400  consistent with an embodiment of the disclosure for providing a backflow blocking apparatus. Method  400  may be implemented using, for example, a machine capable of cutting, stamping, punching, and folding a sheet. Ways to implement the stages of method  400  will be described in greater detail below. 
     Method  400  may begin at starting block  405  and proceed to stage  410  where plurality of flaps  210  may be cut out of first section  204  of sheet  202 . Plurality of flaps  210  may be retained by first section  204  of sheet  202 . For example, plurality of flaps  210  may be created by cutting a respective and associated plurality of slits  248  in first section  204 . Plurality of flaps  210  may be retained by first section  204  using the respective and associated plurality of retention members  212 . 
     From stage  410 , where plurality of flaps  210  are cut out of first section  204  of sheet  202 , method  400  may advance to stage  420  where plurality of openings  246  may be provided in second section  206  of sheet  202  to provide guard structure  238 . For example, plurality of openings  246  may be provided in such a way as to create first plurality of cross members  242  and second plurality of cross members  244 . First plurality of cross members  242  may be periductular to second plurality of cross members  244 . Plurality of openings  246  may be any shape including, for example, rectangular. Plurality of openings  246  may be punched out of second section  206  of sheet  202 . 
     Once plurality of openings  246  are provided in second section  206  of sheet  202  to provide guard structure  238  in stage  420 , method  400  may continue to stage  430  where first section  204  and second section  206  may be folded on one another about fold  208 . For example, guard structure  238  may inhibit the movement of plurality of flaps  210  in a direction toward guard structure  238  when first section  204  and second section  206  are folded on one another. Once first section  204  and second section  206  may be folded on one another about fold  208  in stage  430 , method  400  may then end at stage  440 . 
     Embodiments of the disclosure may provide a backflow blocking apparatus. The apparatus may comprise a first section of a sheet, the first section comprising a plurality of flaps cut out of and retained by the first section of the sheet; a second section of the sheet, the second section comprising a guard structure; and a fold about which the first section and the second section are folded on one another, wherein the guard structure inhibits the movement of the plurality of flaps in a direction toward the guard structure when the first section and the second section are folded on one another. The first section of the sheet and the second section of the sheet may comprise a same size. The first section of the sheet and the second section of the sheet may comprise a same shape. The first section of the sheet may comprise a plurality of first section sides having a same length and the second section of the sheet may comprise a plurality of second section sides having the same length. The first section of the sheet may comprise a plurality of fasten openings. Each of the plurality of flaps may comprise a corresponding plurality of retention members about which each of the plurality of flaps rotates when each of the plurality of flaps rotate from an open and a closed position. Each of the plurality of flaps may be triangular. The guard structure may comprise a first plurality of cross members and a second plurality of cross members. The first plurality of cross members may be periductular to the second plurality of cross members. The guard structure may comprise a plurality of openings made in the second section of the sheet. The plurality of openings may be rectangular. The apparatus may be mounted on a 40 mm by 40 mm fan. The sheet may comprise a thickness of between 0.004 inches and 0.006 inches. The sheet may comprise a thickness of between 0.0085 inches and 0.013 inches. The sheet may comprise flame retardant polypropylene. 
     Embodiments of the disclosure may provide a backflow blocking apparatus. The apparatus may comprise a first section of a sheet, the first section comprising a plurality of flaps cut out of and retained by the first section of the sheet wherein each of the plurality of flaps comprises a corresponding retention member about which each of the plurality of flaps are configured to rotate; and a second section of the sheet, the second section comprising a guard structure wherein the guard structure comprises a first plurality of cross members and a second plurality of cross members, wherein the first plurality of cross members are periductular to the second plurality of cross members. The first section of the sheet may comprise a plurality of fasten openings. 
     Embodiments of the disclosure may comprise a method for providing a backflow blocking apparatus. The method may comprise: cutting a plurality of flaps cut out of a first section of a sheet wherein the plurality of flaps are retained by the first section of the sheet; providing a plurality of openings in a second section of the sheet to provide a guard structure; and folding the first section and the second section on one another about a fold, wherein the guard structure inhibits the movement of the plurality of flaps in a direction toward the guard structure when the first section and the second section are folded on one another. The method may further comprise providing a plurality of fasten openings in the first section of the sheet. The plurality of openings may be rectangular. 
     Embodiments of the present disclosure, for example, are described above with reference to block diagrams and/or operational illustrations of methods, systems, and computer program products according to embodiments of the disclosure. The functions/acts noted in the blocks may occur out of the order as shown in any flowchart. For example, two blocks shown in succession may in fact be executed substantially concurrently or the blocks may sometimes be executed in the reverse order, depending upon the functionality/acts involved. 
     While the specification includes examples, the disclosure&#39;s scope is indicated by the following claims. Furthermore, while the specification has been described in language specific to structural features and/or methodological acts, the claims are not limited to the features or acts described above. Rather, the specific features and acts described above are disclosed as example for embodiments of the disclosure.