FIELD OF THE INVENTION  
         [0001]    The invention relates to a fan grill for use with a fan.  
         BACKGROUND OF THE INVENTION  
         [0002]    Fans are often used to cool equipment that produces undesirable heat. Fans provide air circulation to distribute cooler air to and/or within equipment and to remove and exhaust warm air from equipment. For example, systems used with communications and information technology equipment employ fans to provide cooler air and/or to dissipate or remove heat produced by electronic components that may be undesirable. Rack-mounted equipment housed within racks and/or cabinets or other enclosures is particularly vulnerable to heat that can affect the performance and/or useful life of electronic components. To help protect the fans associated with equipment, fan grills and fan guards may be used to help prevent objects and to help inhibit debris from contacting fan blades and entering the fans.  
         SUMMARY OF THE INVENTION  
         [0003]    In general, in an aspect, the invention provides a fan guard for use with a fan associated with an inlet including a wall defining a port. The fan guard includes a grate configured to inhibit insertion of a finger through the grate while permitting passage of air through the grate, a first bias member connected to the grate and configured to be biased against a first side of the wall of the inlet while the fan guard is mounted to the inlet, and a second bias member connected to the grate and configured to be biased against a second side of the wall of the inlet while the fan guard is mounted to the inlet.  
           [0004]    Implementations of the invention may include one or more of the following features. The first bias member is flexible to bias the first and second bias members against respective sides of the inlet while the fan guard is mounted to the inlet. The first side is a bottom lower edge of the wall of the inlet and the first bias member includes a tab configured to connect to the bottom lower edge of the wall of the inlet. The tab comprises a stepped portion configured to connect to the bottom lower edge. The second bias member includes an elongated member extending from the grate and has a terminal end configured to mate with the second side of the wall of the inlet. The terminal end of the elongated member is concave.  
           [0005]    Implementations of the invention may also include one or more of the following features. The first bias member includes a circumferential ridge configured to connect to the first side of the wall of the inlet. The first side is a bottom lower edge of the wall of the inlet and the circumferential ridge comprises a stepped portion configured to connect to the bottom lower edge. The second bias member includes an outermost rib defining a perimeter of the grate and has a concave outer surface.  
           [0006]    Implementations of the invention may further include one or more of the following features. The fan guard is configured such that a top of the fan guard is substantially even with a top of the wall of the inlet when the fan guard is mounted to the inlet. The grate and the first and second bias members are configured such that the fan guard is inserted in the inlet and the first and second bias members are biased against respective sides of the inlet to mount the fan guard to the inlet. The fan guard is constructed of at least one of a plastic, a metal, a ceramic and a composite.  
           [0007]    In general, in another aspect, the invention provides a fan guard for use with a fan associated with an inlet in a housing, the inlet having a bottom side defining a port and an inner side for guiding gas to the port and the housing having a surface in which the inlet is disposed. The fan guard includes a grate configured to inhibit insertion of a finger through the grate while permitting passage of air through the grate, means for biasing the fan guard upward against the bottom side of the inlet while the fan guard is mounted to the inlet, and means for biasing the fan guard downward against the inner side of the inlet while the fan guard is mounted to the inlet.  
           [0008]    Implementations of the invention may include one or more of the following features. The means for biasing the fan guard upward against the wall includes a multiple of tabs connected to the grate and configured to connect to the bottom side of the inlet. Each tab includes a stepped portion configured to connect to the bottom side. The means for biasing the fan guard downward against the inner side includes a multiple of support ribs having terminal ends configured to mate with the inner side of the inlet. Each terminal end is concave. The fan guard is configured to be flush-mounted such that a top of the fan guard is substantially even with the surface of the housing, in which the inlet is disposed, while the fan guard is mounted in the inlet.  
           [0009]    In general, in still another aspect, the invention provides a method of mounting a fan guard to a housing, the fan guard including a grate configured to inhibit passage of a finger through the grate while allowing passage of gas through the grate, the housing including an inlet having a bottom surface defining a port and an inner surface configured to direct gas to the port, the fan guard further including multiple tabs coupled to the grate and multiple ribs extending from the grate and having terminal ends adapted to mate with the inner surface. The method includes inserting the fan guard into the inlet, aligning the fan guard with the port, bending the tabs connected to the grate relative to the grate and inserting the tabs through the port to connect the tabs with the bottom surface, and allowing the tabs to bias the tabs and the terminal ends of the ribs against the bottom and inner surfaces, respectively, with the terminal ends of the ribs with the wall.  
           [0010]    Implementations of the invention may include one or more of the following features. The bending and inserting of the tabs includes applying force to at least one of a top of the fan grill and the tabs.  
           [0011]    Various aspects of the invention may provide one or more of the following advantages. A fan grill can be flush mounted to a gas, e.g., air, inlet ring associated with a fan. The fan grill can serve as a safety guard to help prevent finger insertion into, and to inhibit debris from entering, a fan while impeding and disturbing gas flow to the fan less than by using a non-flush mounted fan grill. The fan grill can impede and disturb gas flow to a fan less, e.g., about eight percent, than compared to gas flow to the fan without a fan grill or guard. The fan grill can be readily installed in a gas inlet ring that provides gas flow to a fan. The fan grill can securely connect to a gas inlet ring without mounting hardware, and can be used with existing gas inlet rings and fans. Insertion and/or removal of rack-mounted equipment may be facilitated.  
           [0012]    These and other advantages of the invention, along with the invention itself, will be more fully understood after a review of the following figures, detailed description, and claims.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]    [0013]FIG. 1 is a perspective view of a ventilated rack-mounted component system including a fan grill.  
         [0014]    [0014]FIG. 2 is a top view of the fan grill shown in FIG. 1.  
         [0015]    [0015]FIG. 3 is a top view of portions of the fan grill, a fan and a housing shown in FIG. 1.  
         [0016]    [0016]FIG. 4 is a cross sectional view of FIG. 3 at A-A and at B-B.  
         [0017]    [0017]FIG. 5 is a flow diagram of a method for mounting the fan grill shown in FIG. 1 to a housing shown in FIG. 1. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0018]    Illustrative embodiments of the invention provide a fan grill for protecting a fan. More particularly, a fan grill is provided that may inhibit objects from entering and damaging a fan. The fan grill is preferably mounted to a gas inlet ring associated with a fan. The gas inlet ring defines a gas port that is positioned adjacent to an array of fan blades of the fan and helps guide gas to the fan. The fan grill is connected to the gas inlet ring to help inhibit objects from passing through the gas port and contacting the fan blades. Other embodiments of the fan grill are within the scope of the invention.  
         [0019]    Referring to FIGS.  1 - 2 , a ventilated rack-mounted component system  8  includes a housing  21 , a fan grill  10 , and a fan  9 . The system  8  is configured to hold and exhaust heat from electronic equipment contained by the housing  8 . The fan  9  is configured to expel hot or warm gas, e.g., air, from inside the housing  8  out of the housing  8  through a gas port  15  defined by a gas inlet ring  11 , which is formed in the housing  8 . The fan  9  may include, but is not limited to, motorized impellers, e.g., centrifugal impellers and, as shown in FIG. 2 for illustrative purposes, backward curved impellers  7 . The fan grill  10  is configured and disposed to inhibit objects entering the housing  8  through the gas port  15 .  
         [0020]    Referring to FIG. 2, the fan grill  10  comprises radial ribs  22 , concentric circular ribs  28 , radial support ribs  26 , and tabs  30 . The radial ribs  22 , concentric circular ribs  28  and radial support ribs  26  are depicted in FIG. 2 to comprise a portion of the fan grill  10  for illustrative purposes only to show a relation of the fan grill  10  to the fan  9  and fan blades  7 , e.g., backward curved impellers, and it is understood that the ribs  22 ,  26  and  28  comprise the fan grill  10  of FIG. 1.  
         [0021]    The ribs  22 ,  26  and  28  form a grate  36  configured to inhibit objects, e.g., a person&#39;s finger, from fitting through the grate  36  and reaching the fan  9 , and to help inhibit debris from falling through the grate  36 . The grate  36  is configured not to have openings and/or to provide an opening between the grate and the gas inlet ring  11  that are not greater than about 0.25 inch.  
         [0022]    As shown, the fan grill  10  includes four of the radial ribs  22  equally spaced angularly about and extending from a center ring  20 , and eight of the concentric circular ribs  28  equally spaced radially from the center ring  20  and coupled to the radial ribs  22 . Each of the radial support ribs  26  extends beyond an outermost circular rib  24  and is connected to several, here five, of the concentric circular ribs  28 . Each tab  30  is connected to the outermost circular rib  24  and is aligned with one of the radial ribs  22 . The fan grill  10 , however, is not limited to the configuration shown in FIGS.  1 - 2 .  
         [0023]    Referring to FIGS.  3 - 4 , the tabs  30  and the radial support ribs  26  are configured to securely connect the fan grill  10  to a wall  13  of the gas inlet ring  11 . The tabs  30  can engage a lower edge  17  of the wall  13  that extends downward away from a top  12  of the gas inlet ring  11  and that defines the gas port  15 . Terminal ends  32  of the radial support ribs  26  are configured to mate with the wall  13 . The tabs  30  and the radial support ribs  26  are configured to be biased against the lower edge  17  and the wall  13  when the fan grill  10  is mounted in the gas inlet ring  11 . The tabs  20  are configured to bias upward against the lower edge  17  of the wall  13  and the radial support ribs  26  are configured to bias downward against the wall  13 . The tabs  30  and the radial support ribs  26  are not coplanar. FIG. 4 shows the superposition of the planes of the tabs  30  and the radial support ribs  26  for illustrative purposes. The fan grill  10  is further configured such that, when mounted, a top  23  of the fan grill  10  is substantially even, e.g., even, slightly above, or slightly below, a plane  19  of the housing  21 .  
         [0024]    Each tab  30  includes a stepped portion  34  configured to engage the lower edge  17  of the gas inlet ring  11 . The stepped portion  34  helps resist an upward force, e.g., gas exhausted by fan blades  7 , applied to a bottom surface (not shown) of the fan grill  10  and helps secure the fan grill  10  in the gas inlet port  15 .  
         [0025]    Each terminal end  32  of each radial support rib  26  is configured to conform to the wall  13  of the gas inlet ring  11 . Each terminal end  32  includes a substantially concave shape to mate with a substantially convex shape of the wall  13 . The terminal ends  32  help the fan grill  10  engage the gas inlet ring  11  below the plane  19  of the housing  12 . The radial support ribs  26  help resist a downward force applied to the top  23  of the fan grill  10  and help secure the fan grill in the gas inlet ring  11 . The configurations of the terminal ends  32  are not limited to the substantially concave shape shown in FIGS.  3 - 4 , but may include other configurations to mate the radial support ribs  26  with the wall  13  of the gas inlet ring  11 .  
         [0026]    The fan grill  10  is preferably constructed of a suitable material for use with units and assemblies in which fans are incorporated, e.g., gas distribution units of server racks. Suitable materials include, but are not limited to, plastics, e.g., acrylonitrile butadiene styrene (ABS), polyethylene, polypropylene, metals, e.g., aluminum, ceramics, composites and combinations of such materials. Connections between the ribs  22 ,  24 ,  26  and  28  are achieved by a method well known in the art, e.g., molding (for ABS) or brazing, which is suitable for use with the material(s) used to make the fan grill  10 . The connections and material provide flexibility in the fan grill  10  to help with mounting of the fan grill  10  to the housing  8  and to help the tabs  30  and the radial support ribs  26  bias the fan grill  10  in place.  
         [0027]    Referring to FIG. 5, with further reference to FIGS.  1 - 4 , a flow diagram illustrates a method for mounting the fan grill  10  to the housing  8 . The method comprises inserting the fan grill  10  into the gas inlet ring  11  of the fan  9  ( 100 ) and aligning the fan grill  10  with the gas port  15  ( 200 ). The method further comprises bending the tabs  30  and inserting the tabs  30  thru the gas port  15  to connect the stepped portions  34  with the bottom lower edge  17  of the wall  13  of the gas inlet ring  11 , e.g., by applying a force to the top  23  of the fan grill  10  and/or by applying a force on the tabs  30  ( 300 ). The method also comprises mating the terminal ends  32  of the radial support ribs  26  to the wall  13  of the gas inlet ring  11 , e.g., by applying a force to the top  23  of the fan grill  10  and/or by applying a force on the tabs  30  ( 400 ).  
         [0028]    Other embodiments are within the scope and spirit of the appended claims. For example, the fan grill  10  may include a different number of the radial ribs  22 , the radial support ribs  26  and/or the circular concentric ribs  28  and may include different spacings between the ribs  22 ,  24 ,  26  and/or  28 , and/or different spacings between the fan grill  10  and the gas inlet ring  11 . The fan grill also may include different structures and/or configurations, e.g., fine gage mesh and other materials having a multiple of apertures, other than, or in addition to, the ribs  22 ,  24 ,  26 , and/or  28  to form the grate  36 .  
         [0029]    The fan grill  10  may include a different number of tabs  30  connected to the outermost circular rib  24 . The tabs  30  may be connected to the other portions of the fan grill  10  in manners other than, or in addition to, being connected to the outermost circular rib  24 . The fan grill  10  also may include different structures and/or configurations other than the tabs  30  configured to bias upward against the lower edge  17  of the wall  13  of the gas inlet ring  11  when the fan grill  10  is mounted in the ring  11 . For example, the fan grill  10  may include a circumferential ridge attached to a perimeter of the grate  36  and configured to connect to the lower edge  17 .  
         [0030]    In addition, the fan grill may include different structures and/or configurations other than the radial support ribs  26  configured to bias downward against the wall  13  when the fan grill  10  is mounted to the gas inlet ring  11 . For example, the fan grill  10  may include the outermost circular rib  24  having a concave shape to mate with the wall  13  of the gas inlet ring  11 .  
         [0031]    Various alterations, modifications and improvements to the above description will readily occur to those skilled in the art. Such alterations, modifications and improvements are within the scope and spirit of the invention. Accordingly, the foregoing description is by way of example only and is not limiting. The invention&#39;s limit is defined only in the following claims and the equivalents thereto.
A fan grill for use with a fan associated with an inlet ring is configured to flush mount in an inlet ring and to serve as a safety guard to help prevent finger insertion into, and to help inhibit debris from entering a fan. The fan grill can impede and disturb gas flow to a fan less than by using a non-flush mounted grill or guard. The fan grill includes radial ribs, concentric circular ribs and radial support ribs to form a grate, and tabs. The tabs and the radial support ribs are configured to bias the fan grill against a wall of an inlet ring to securely connect the fan grill in the inlet ring. The fan grill can be readily installed and securely connected to inlet rings or housings of existing fans.