Abstract:
The present invention provides a system to mount a group of fans on the system board of a computer server. The mounting system allows for the fans to be installed or removed as a group or as individual components without the use of tools. The fans are preferably hot-pluggable, or capable of being installed or removed without having to turn off the server. Therefore, an entire group of fans can be removed from a server without using any tools or having to power down the system. The fans can also be removed and installed as individual units, without effecting the other fans in the group.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     Not applicable. 
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not Applicable. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a structural method of mounting fans on a computer system board. More precisely, the present invention relates to a mounting arrangement allowing the installation and removal of one or more hot-pluggable fans, either individually or as a group, in without the use of tools. 
     2. Background of the Invention 
     The necessity for specialized computer equipment has increased dramatically over recent years. Corporations, both large and small, as well as individual consumers have come to depend on computers to enhance and assist them in a broad assortment of tasks. For the individual or small business, personal computers are typically relatively compact and streamlined, often comprising a monitor, a keyboard, a mouse, and a CPU “box” that sits on a desktop or on the floor. These personal computers, although considered compact when deployed in relatively small numbers, can be quite cumbersome and bulky when deployed in larger quantities. It is not uncommon for an organization to require several computers to act as servers controlling their local area networks. For larger corporations that require numerous servers, the traditional CPU package is not practical to house servers. For such operations, an industry standard EIA (Electronics Industries Alliance) rack is often used to contain servers in a stacked arrangement that uses the available space more efficiently. 
     Such electronics racks are relatively simple structures that closely resemble open-frame bookcases. Computer server/component racks are typically constructed with perforated, hinged front-doors, rigid sides and a removable rear panel. Industry standard 19″ EIA electronics racks are designed typically to house a column of electronics packages that are 17¾″ in width and with varying depths. The height of an electronics package can vary but, to be compatible with the rack mounting structure, must be an integer multiple of an EIA unit called simply the “U.” An EIA U is 1.75 inches. Electronic equipment generally has a height in multiples of “Us” e.g., 1 U (1.75″), 2 U (3.50″), 3 U (5.25″), etc. Although it is preferred that the height of the electronics components be a multiple of the standard EIA unit U, the dimension of the EIA unit is understood to represent a maximum allowable height, including both the height of the component and any clearance required. This amount of clearance aides in the installation of the rack mounted electronics and promotes interference free insertion and removal. 
     Typically, electronic components may be secured within the rack using a pair of drawer slides. The drawer slides, usually ball-bearing supported rails, are secured in place within the rack frame. Corresponding rails are located on the side surfaces of the electronics component to be mounted, thus allowing the component to be pulled in and out of the rack frame easily to allow quick and frequent access. 
     As the computing needs of both large and small businesses increase, there is increasing demand for computer servers to become smaller and more compact. This demand is coupled with the demand that the systems be easier to maintain and service. A typical server comprises at least one, often times more than one, of each of the following components: system board including processors and memory; power supplies; disk drives, including hard disks, floppy drives, CD-ROM drives, etc.; peripheral component interface (PCI) buses, and cooling fans. Mounting all of these components in a dense packed server, some as small as 1 U or 2 U, creates many interface issues associated with maintaining and accessing the server. 
     The cooling fans in a server may have to be removed and installed, both for servicing the fan and servicing other components. A typical server has several fans for circulating air through the system to aid in controlling the temperature. These fans run essentially continuously and will likely have to be replaced several times during the life of the server in the event of a fan failure. Additionally, many other standard maintenance tasks for the server include first removing the fans in order to gain better access to other components. Most prior art cooling fans were fixed in place by one or more screws, which made the removal of a bank of several fans a tedious and time consuming process. 
     Therefore, there remains a need in the art for an arrangement that allows for easy installation and removal of fans from a server computer without using any tools. The present invention overcomes the deficiencies of the prior art while focusing on these needs. 
     BRIEF SUMMARY OF THE INVENTION 
     The present invention overcomes the deficiencies of the prior art by providing a system to mount a group of fans on the system board of a computer server. The mounting system allows for the fans to be installed or removed as a group or as individual components without the use of tools. The fans are hot-pluggable, or capable of being installed or removed without having to turn off the server. Therefore, an entire group of fans can be removed from a server without using any tools or having to power down the system. The fans can also be removed and installed as individual units, without effecting the other fans in the group. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     For a more detailed description of the preferred embodiment of the present invention, reference will now be made to the accompanying drawings, wherein: 
     FIG. 1 is a perspective view of a dense server constructed in accordance with one embodiment of the present invention; 
     FIG. 2 is a vertical view of single fan assembly; 
     FIG. 3 is a partial cross-sectioned vertical view of a fan cage constructed in accordance with one embodiment of the present invention; 
     FIG. 4 is a vertical view of a fan cage assembly constructed in accordance with one embodiment of the present invention; 
     FIG. 5 is a perspective view of a portion of a dense server adapted to receive a fan cage assembly constructed in accordance with one embodiment of the present invention; 
     FIG. 6 is a perspective view of a portion of a dense server with a fan cage assembly with all fans installed; and 
     FIG. 7 is a perspective view of a portion of a dense server with a fan cage assembly with one fan removed. 
    
    
     NOTATION AND NOMENCLATURE 
     Certain terms are used throughout the following description and claims to refer to particular system components. As one skilled in the art will appreciate, computer companies may refer to a component by different names. This document does not intend to distinguish between components that differ in name but not function. In the following discussion and in the claims, the terms “including” and “comprising” are used in an open-ended fashion, and thus should be interpreted to mean “including, but not limited to . . . ”. Also, the term “couple” or “couples” is intended to mean either an indirect or direct electrical connection. Thus, if a first device couples to a second device, that connection may be through a direct electrical connection, or through an indirect electrical connection via other devices and connections. 
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     In the description that follows, like parts are marked throughout the specification and drawings with the same reference numerals, respectively. The drawing figures are not necessarily to scale. Certain features of the invention may be shown exaggerated in scale or in somewhat schematic form and some details of conventional elements may not be shown in the interest of clarity and conciseness. 
     The present invention relates to methods and apparatus for accessing and servicing computer cooling fans. In order to fully describe the preferred embodiments of the present invention, reference will be made throughout this description to a computer server, but the concepts of the present invention may find utility in other types of computers and in a non-computer electronic environment. The present invention is susceptible to embodiments of different forms. There are shown in the drawings, and herein will be described in detail, specific embodiments of the present invention with the understanding that the present disclosure is to be considered an exemplification of the principles of the invention, and is not intended to limit the invention to that illustrated and described herein. 
     Referring to FIG. 1, a server assembly  10  is shown comprising a system board  12 , disk drives  14 , power supplies  16 , a PCI cage assembly  19 , and a fan cage assembly  20 . A slide rail  22  is located on either side of the chassis  24  and interfaces with the server cabinet (not shown). During normal operation, a cover (not shown) attaches to the chassis  24  fully enclosing the server assembly  10  and the assembly is contained within a server cabinet. To perform maintenance on the server assembly  10 , the assembly is partially extended from the cabinet on rails, somewhat like a drawer being opened. The cover is then removed to expose the internal components. 
     Now referring to FIG. 2, a fan assembly  26  comprises an electric fan  28 , a housing  30 , a spring latch  34 , and an electrical plug  32 . Electric fan  28  may be any compact electrical fan as used in electronic cooling applications. Electric fan  28  is powered by electrical current supplied from the equipment being cooled, e.g., server  10 , through blind mating electrical plug  32 . Housing  30  provides support and protection for the fan  28  and is adapted to interface with a fan cage (FIG.  3 ). Housing  30  further includes a spring latch  34  or other easily manipulated latching mechanism for securing the housing  30  to the fan cage. 
     Referring now to FIG. 3, one embodiment of a fan cage  36  is capable of holding 6 fans. The fan cage  36  generally comprises two end portions  44  and two side portions  46  (only one side portion is shown) integrally connected to a base  42  forming a rectangular receptacle having an open top. Each side portion  46  has an equal number of protrusions  50  in direct opposition to corresponding protrusions (not shown) on the other side of portion  46 . Between each pair of protrusions  50  is a retainer wall  48 . The side portions  46 , base  42 , and retaining walls  48  form receptacles  38  sized to hold a single fan assembly  26 . The base  42  has openings to allow the electrical plug  32  to extend below the fan cage  36 . Retaining walls  48  provide an attachment point for interfacing with the spring latch  34  of the fan assembly. Each end portion  44  also includes a spring latch  40  or other easily manipulated latching mechanism for securing the fan cage  36  to the chassis  24 . 
     Referring now to FIG. 4, the fan cage  36  is shown with all six fan assemblies  26  installed forming a fan cage assembly  20 . The fan assemblies  26  are installed into the fan cage  36  by simply pressing the fan assemblies into the receptacles  38 . Spring latch  34  is preferably designed to automatically latch the fan assembly  26  in place when the assembly is in the proper position relative to the fan cage  36 . The openings for the electrical plugs  32  ensure that the fan assemblies  26  can only be installed in a single orientation, preferably with all the fan assemblies facing the same direction. 
     Referring now to FIG. 5, a simplified view of a portion of the server of FIG. 1 is shown with the fan cage assembly  20  removed. Visible on the system board  12  are the hot-plug sockets  52  that interface with the blind mating plugs  32  on the fan assemblies  26 . Attached to the chassis  24  are brackets  54  that provide attachment points for the spring latches  40  on the fan cage  36 . These brackets  54  provide a stable mounting position for the fan cage assembly  20 . 
     As shown in FIG. 6, fan cage assembly  20  can be installed onto system board  12  by simply pressing the assembly into place. Spring latches  40  preferably engage brackets  54  as the cage  36  is moved downward. Fan cage assembly  20  can be installed with any number of individual fan assemblies  26  installed. Blind mating electrical plugs  32  engage sockets  52  as the fan cage assembly  20  is installed. FIG. 6 shows the fan cage assembly  20  installed on system board  12  with all fan assemblies  26  installed. The cage  36  can also be installed in the server  10  without any fan assemblies  26 . After installation of cage  36 , the individual fan assemblies  26  can subsequently be installed one at a time into cage  36 . 
     The fan cage assembly  20  can be removed from the system board  12  by releasing the spring latches  40  and lifting out the entire assembly. This method can be used to remove the entire fan cage assembly  20 , including all fan assemblies  26 , at one time without the use of any tools. If the fan assemblies  26  are hot-pluggable, the removal can occur while the server is operating. 
     Alternatively, as shown in FIG. 7, an individual fan assembly  26  can be removed from the cage  36  by releasing latch  34  and lifting that particular assembly. This removal can be accomplished without disturbing the other individual fan assemblies  26 . Thus, individual fans can be removed and replaced while the server and other fans are running. 
     The embodiments of the present invention provide a flexible system for installing and removing cooling fans from electronic devices. Individual fans can be installed and removed as individuals or as one of many fans in a fan cage assembly. The fans and fan cage assembly can be easily removed without using tools or having to manipulate loose hardware. Thus, the embodiments of the present invention provide quick and simple alternatives for maintaining cooling fans, thereby lowering maintenance costs. These savings are particularly beneficial in large computer server applications that use hundreds or thousands of servers with each server having several cooling fans. 
     While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that the drawings and detailed description thereto are not intended to limit the invention to the particular form disclosed, but on the contrary, the intention is to cover all modifications, equivalents and alternatives falling within the spirit and scope of the present invention as defined by the appended claims.