Abstract:
An assembly includes a fan housing that includes a casing and a stator disposed radially inward of the casing and adapted to receive a rotor assembly. Struts attach the stator to the casing. One or more of the struts may define a channel for routing one or more electrical wires. A fan guard helps prevent accidental contacting of the fan blades. The fan guard may be mounted to the struts and may be flush with the housing, and/or may be adapted to cover at least a portion of the channel, thereby trapping the electrical wire(s) in the channel.

Description:
TECHNICAL FIELD 
     This invention relates to electric fans and fan guards, and to methods for mounting such guards. 
     BACKGROUNDS OF THE INVENTION 
     Many systems employ fans to move air (or some other fluid). For example, desktop and laptop computers, as well as many other types of electronic systems, often have internal electric fans that generate air flow to help cool internal components (e.g., the hard drive, integrated circuits, power supply, etc.). 
     In an electric fan, airflow is produced by a plurality of rotating fan blades, which are in turn driven by an electric motor. The motor and blades are usually supported by a stator, which in turn may be supported by struts coupled to an outer casing. 
     As might be expected, it is generally desirable to prevent accidental contacting of the fan blades. Fan guards have been developed for this purpose. At present, the design of fan guards is addressed by numerous national and international safety standards. 
     In many systems, it is generally desirable to provide a fan guard that does not unduly impede the airflow (or other fluid flow). 
     In addition, it is often desirable to be able to provide a guard that is flush with the housing so as not to increase the dimensions of the fan. One method of not increasing the dimensions is to fasten the guard to the inner surfaces of the fan housing, for example, as disclosed in U.S. Pat. Nos. 5,951,257 and 5,749,708. 
     One drawback associated with this method is that the fastening hardware is more complex than desired. Another drawback is that the fastening hardware can impede the airflow (or other fluid flow) more than desired. 
     Another method to provide a guard that is flush with the housing is to form the housing with an integral fan guard. 
     However, the tooling required to form the housing with an integral fan guard is often more complex than desired. Another drawback associated with integral guards is that national and international safety standards can differ from one another and are subject to change. Consequently, a manufacturer would need to have a variety of housing designs in order to address each potential set of guard requirements. 
     It is also generally desirable to prevent the electrical wires of the fan from getting into the path of the rotating fan blades. One conventional method involves clipping the wires to structural members of the fan housing. 
     One drawback associated with this method is that the use of clips adds cost and labor to the system. 
     Accordingly, it is an object of the present invention to provide fan guards and methods for mounting such guards that overcome one or more of the above described drawbacks of the prior art. 
     SUMMARY OF THE INVENTION 
     According to a first aspect of the present invention, an assembly includes a fan housing that includes a casing and a stator, the stator being disposed radially inward of the casing and adapted to receive a rotor assembly. A strut attaches the stator to the casing. The assembly further includes a guard that engages the stator to retain the guard to the strut to help retain the guard to the fan housing. 
     According to another aspect of the present invention, an assembly includes a fan housing that includes a stator, a casing, and a strut that attaches the stator to the casing. The assembly further includes a guard having means for engaging the strut to help retain the guard to the fan housing. 
     According to another aspect of the present invention, a method is provided for use in association with a fan housing that includes a stator, a casing, and a strut that attaches the stator to the casing. The method includes providing a fan guard and retaining the guard to the strut. 
     According to another aspect of the present invention, an assembly includes a fan housing that includes a casing, a stator, and a strut having a radially extending channel with at least one electrical wire routed therethrough. The assembly further includes a guard that includes a surface that covers at least a portion of the channel when the guard is mounted to the fan housing, thereby trapping the electrical wire(s) in the channel. 
     According to another aspect of the present invention, an assembly includes a fan housing that includes a casing, a stator, and a strut having a radially extending channel with at least one electrical wire routed therethrough. The assembly further includes a guard that includes means for trapping the electrical wire(s) in the channel when the guard is mounted to the fan housing. 
     According to another aspect of the present invention, a method includes providing a fan housing that includes a stator, a casing, and a strut having a radially extending channel. The method further includes routing at least one electrical wire through the channel and covering at least a portion of the channel with a guard mounted to the housing to thereby trap the electrical wire in said channel. 
     According to another aspect of the present invention, a fan guard for a fan housing that includes a stator, a casing, and a strut that attaches the stator to the casing is provided. The fan guard includes a grill and a clip that extends radially, wherein the clip is adapted to engage the strut to retain the guard to the strut. 
     It should be understood that the various aspects of the present invention may be employed individually and/or in any combination thereof. 
     One advantage of the currently preferred embodiments of the present invention is that the guard is snapped to a strut that supports the stator. Snapping the guard to an existing structure helps minimize any impact to airflow. 
     Another advantage of the currently preferred embodiments is that the guard may be made flush with the housing, so as not to increase the dimensions of the fan. 
     Another advantage of the currently preferred embodiments is that there is no need for the complex tooling that would be needed to fabricate a housing with an integral guard. 
     Furthermore, because the guard is formed separate from the housing and then mounted thereto, differing sets of customer guard requirements can be met by merely providing different guards. Thus, there is no need to have a different housing design for each potential set of guard requirements. 
     Another advantage of the currently preferred embodiments is that the electrical wires are retained without the need for clips, thereby eliminating the cost and labor normally associated with the use of clips. 
     Other advantages of the present invention will become apparent in view of the following detailed description of preferred embodiments, claims, and accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a computer enclosure with the top wall removed to reveal a fan having a guard in accordance with one embodiment of the present invention; 
         FIG. 2  is an enlarged perspective view of the fan of  FIG. 1 ; 
         FIG. 3  is a rear elevational view of the fan housing of  FIG. 2  with the guard of  FIG. 2  assembled thereon; 
         FIG. 4  is a cross-sectional view of the strut and guard of  FIG. 3  taken in the direction of L—L; 
         FIG. 5  is a cross-sectional view of the fan housing of  FIG. 3  with the guard of  FIG. 3  assembled thereon, taken in the direction of G—G; 
         FIG. 6  is a front elevational view of the fan housing of  FIG. 3  with the guard of  FIG. 3  assembled thereon; and 
         FIG. 7  is an enlarged, front perspective view of a portion of the strut and guard of  FIG. 6 . 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  is a perspective view of a computer  20  (shown partially assembled) that employs a fan having a guard according to one embodiment of the present invention. The computer  20  include a printed circuit board  22 , a power supply  24 , an enclosure  26  and a fan  28 . The printed circuit board includes a plurality of integrated circuits  30  and connectors  32 . The enclosure  26  includes a base  34  and side walls  36 ,  38 ,  40 ,  42 . The fan  28  is mounted in the side wall  40  and produces airflow to cool the internal components (e.g., power supply  24  and printed circuit board  22  including integrated circuits  30  and connectors  32 ) of the computer  20 . 
     The fan  28  includes a housing  50 , a guard  52 , and rotor assembly (such as for example, a rotor assembly  70  shown in phantom ( FIG. 2 )). The housing  50 , guard  52 , and rotor assembly  70  are further described hereinafter with respect to  FIG. 2 . 
       FIG. 2  is an enlarged, partially exploded, perspective view of one embodiment of the housing  50  and guard  52 . In this embodiment, the housing  50  includes a casing  54  and a stator  56 . The casing  54  and the stator  56  are disposed about a longitudinal axis (or axis of rotation)  57 . The casing  54  includes a substantially annular portion  58  (referred to hereafter as “annular portion”) having a substantially annular radial inner surface  59 . The stator  56  has a substantially annular radial outer surface  60 . The radial inner surface  59  of the substantially annular portion  58  and the radial outer surface  60  of the stator  56  generally define a substantially annular flow path  61  therebetween. 
     The casing  54  further includes flanges  62 . Through holes  64  in the flanges  62  are each adapted to receive a fastener, such as, for example, a fastener  66  (shown in phantom), to attach the housing  50  to the enclosure  26  ( FIG. 1 ) or some other structure. The flanges  62  may include stiffeners  68 . 
     The stator  56  is adapted to receive and support a rotor assembly, such as, for example, a rotor assembly  70  (shown in phantom). The illustrated rotor assembly  70  includes a motor  72  and a bladed disk  74 . The motor  72  includes a motor shaft  75 , which is coupled to and drives the bladed disk  74 . The bladed disk  74  is made up of a disk portion  76  and a plurality of blades  78  that extend therefrom. 
     There is typically at least one electrical wire or wires  80  electrically connected to the motor  72 . Electrical wires  80  may, for example, be used to provide electric power to the motor  72 . 
     The housing  50  further includes a plurality of struts  90 ,  92 ,  94 . The struts  90 ,  92 ,  94  extend radially between the casing  54  and the stator  56  to thereby support the stator  56 . Strut  94  has a channel  96  ( FIG. 4 ) that extends the length of the strut  94 . The electrical wire(s) to be connected to the motor to be mounted in the housing  50  (e.g., electrical wires  80  to/from the motor  72 ) may be routed through the channel  96  ( FIG. 4 ). 
     The guard  52  includes a grill  100  and a plurality of clips  102 ,  104 ,  106 . The grill  100  has three substantially concentric rings (i.e., a first ring  110 , a second ring  112 , and a third ring  114 ) and three radially extending members  116 . The radially extending members  116  connect the concentric rings  110 ,  112 ,  114  to one another. Each of the clips  102 ,  104 ,  106  has tabs  120  that extend axially toward the fan housing  50 . (Details of the tabs  120  are further described hereinafter with respect to  FIGS. 4 ,  7 .) As will be further described hereinafter, the clips  102 ,  104 ,  106  are used to mount the guard  52  to the housing  50 . 
     A rear surface of the housing  50  is indicated at  130 . A forward surface is indicated at  132 . An outer facing surface of the guard  52  is indicated at  134 . An inner facing surface is indicated at  136 . In the illustrated embodiment of the present invention, the housing  50  is made of either plastic or metal, such as an injection molded plastic or a die cast aluminum. However, as may be recognized by those of ordinary skill in the pertinent art based in the teachings herein, the housing  50  may be made of any of numerous different materials that are currently known or later become known for performing the function of the housing as described herein. 
     As will be further described hereinafter, the guard  52  is to be snapped onto the housing  50 . 
       FIG. 3  shows the guard  52  mounted on the housing  50 . In this state, the tabs  120  on the clips  102 ,  104 ,  106  engage the struts  90 ,  92 ,  94  and thereby retain the guard  52  to the housing  50 . Details of the manner in which the tabs  120  engage the struts  90 ,  92 ,  94  is further described hereinbelow with respect to  FIG. 4 . 
       FIG. 4  is a cross-sectional view of the strut  94  and the clip of  FIG. 2  taken in the direction of L—L ( FIG. 3 ). The strut  94  has an outer surface  140  and two shoulders  142 ,  144 . The two shoulders  142 ,  144  extend radially and/or circumferentially from the outer surface  140  of the strut  94 . 
     As stated above, the clip  104  has tabs  120  that extend axially toward the housing  50 . Each of the tabs  120  has a hook  146  that engages a respective shoulder  142 ,  144  on the strut  94 . With the hooks  146  engaging the shoulders  144 ,  146 , as shown, the clip  104  is retained to the strut, thereby retaining the guard  52  to the housing  50 . 
     Note that in some embodiments, the strut may have a recess for seating the clip so that the clip does not reduce the cross sectional area of the flow path. 
     To assemble the guard  52  onto the housing  50  as shown in  FIGS. 3 ,  4 , the guard  52  is first suitably positioned relative to the struts  90 ,  92 ,  94  of the housing  50 . Force is then applied so as to force the clips  102 ,  104 ,  106  onto the struts  90 ,  92 ,  94 . The tabs on the clips  102 ,  104 ,  106  spread apart (i.e., the distance between the tabs on a clip increases) when the hooks reach the front of the shoulders (i.e., the axially rear portion of the shoulders). After the hooks pass the shoulders, the hooks come to rest behind the shoulders (i.e., axially forward of the shoulders), thereby retaining the clips  102 ,  104 ,  106  to the struts  90 ,  92 ,  94  and retaining the guard  52  to the housing  50 . 
     With the guard  52  mounted on the housing  50 , the guard  52  extends across at least a portion of the channel  96  and thereby traps any electrical wires (e.g., electrical wires  80 ) ( FIG. 2 ) routed through the channel  96 . 
       FIG. 5  is a cross-sectional view of the guard  52  mounted on the housing  50 , taken in the direction of G—G ( FIG. 3 ). As can be seen, the outer facing surface  134  of the guard is flush (i.e., substantially coplanar) with the rear surface  130  of the housing. Consequently, the guard  52  does not increase the outer dimensions of the housing  50 . 
       FIG. 6  shows a front elevational view of the housing  50  with the guard  52  mounted thereon. 
       FIG. 7  is an enlarged, front elevational view of a portion of the strut  92  with hooks  146  of clip  104  engaged therewith (see insert P- FIG. 6 ). 
     Although the grill portion of the guard described above is substantially annular, this is not required. In addition, even if a grill is substantially annular, it need not comprise concentric rings as shown. For example, in some embodiments, the grill comprises partial rings or annular segments instead of complete rings. The annular segments may collectively form only a portion of a ring. Furthermore, even if a grill comprises complete rings, it need not comprise exactly three concentric rings as shown. For example, in some embodiments, the grill comprises only one or two rings. In some other embodiments, the guard comprises more than three rings. 
     In addition, although the guard described above has three clips to engage the three struts, there is no requirement to engage each and every strut. Moreover, although the clips have tabs with hooks that engage shoulders on the struts, the present invention is not limited to such. For example, some embodiments may employ clips having barbed studs that engage through holes in the struts. Some other embodiments may employ hooks on the struts. Some other embodiments may employ other types of engagements. Still further embodiments may employ combinations of the above. 
     Although the fan housing is shown having flanges with a triangle-like shape, such flanges are not required. For example, some embodiments have flanges with non-triangle-like shapes. Some other embodiments may have no flanges at all. 
     Furthermore, although the struts in the housing extend from the casing to the stator, struts are not limited to such. For example, struts can extend in any direction. Moreover, struts are not limited to the shape shown above. 
     Although the rear surface of the guard is shown flush with the rear surface of the housing, the present invention is not limited to such. For example, in some embodiments, the guard may not be flush with the housing. Moreover, in some embodiments, the guard may be mounted on the forward side of the housing. In such embodiments, the guard may be flush with the forward surface of the housing, although this is not required. 
     Note that, except where otherwise stated, phrases such as, for example, “extends radially” mean “extends in a direction that has, but is not limited to, a radial component.” Thus, for example, “extends radially” means “extends in a direction that is purely radial” or “in a direction that has a radial component in addition to an axial and/or circumferential component”. 
     Also note that, except where otherwise stated, the term “retain” means “releasably retain” or “permanently retain”. 
     Except where otherwise stated, the phrases such as “wire” or “wires” mean any type of electrical leads including for example, but not limited to, insulated wire(s), trace(s), and/or any combination thereof. 
     Note that, except where otherwise stated, phrases such as, for example, “connected to” mean “connected directly to” or “connected indirectly to”. 
     Also note that, except where otherwise stated, terms such as, for example, “comprises”, “has”, “includes”, and all forms thereof, are considered open-ended, so as not to preclude additional elements and/or features. 
     Thus, while there have been shown and described various embodiments, it will be understood by those skilled in the art that the present invention is not limited to such embodiments, which have been presented by way of example only, and that various changes and modifications may be made without departing from the spirit and scope of the invention. Accordingly, the invention is limited only by the appended claims and equivalents thereto.