Abstract:
An electronics chassis, such as a computer chassis including various active electronic components having various heat dissipation rates and operating tolerances. A power supply and various components are housed in an enclosure. A component cooling system causes a first fluid to flow through an area surrounding the electronic components to cool the electronic components through convection. A power supply cooling system causes a second fluid to flow through an area surrounding the power supply to cool the power supply through convection by drawing fluid from an area external of said enclosure and exhausting fluid to an area external of said enclosure. The second fluid is isolated from the first fluid within the enclosure.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The invention relates generally to electronic component chassis and more specifically to a chassis for electronic components, such as a computer chassis, in which a power supply has a cooling system which is isolated from other components.  
         [0003]     2. Description of the Related Art  
         [0004]     It is well known to house various electronic components in an enclosure. In many instances, a power supply for providing operating voltage and current to the components is also housed in the enclosure. The phrase “power supply” as used herein, refers generally to a device having a primary purpose of generating and/or regulating electric operating power supplied to active electronic components. All electronic components other than power supplies are referred to merely as “components” herein. Typically, all electronic components dissipate heat to some degree. Further, power supplies by nature dissipate a relatively large amount of heat as compared to components.  
         [0005]     One example of electronic components housed with a power supply is a computer chassis. Typically, a computer chassis includes a power supply housed in the same enclosure as various computer components, such as motherboards having central processing units (CPUs), memory devices, communication interface devices, and the like. The phrase “computer component” as used herein, refers to any component that is housed in an enclosure of a computer chassis, except for the power supply.  
         [0006]     As computers become more ubiquitous in society, it becomes more desirable to reduce the size of computer chassis. Currently, there is a clear trend toward more powerful and more compact computer chassis. Accordingly, the consumed power per unit density, i.e. the power density, of the average computer has increased tremendously over the past several years. However, such an increase in power density runs into a limitation of heat dissipation. More specifically, the higher the power density, the more heat generated and the more difficult it is to dissipate the heat. Of course, heat adversely affects the operation of most microprocessor based components and other components. Accordingly, the desire to reduce the size and increase the power of computers is at odds with the need to maintain components at temperatures within desired operating ranges. Further, the presence of a power supply in the same enclosure as computer components can adversely effect the operation of the computer components because of the large amount of heat dissipated by the power supply and the generally disparate heat rates and characteristics of power supplies as compared to computer components.  
         [0007]     Essentially, there are two processes by which heat in a computer enclosure is dissipated. The first process is fluid exchange cooling which consists of replacing a heated fluid, such as air, in the enclosure with a cooler fluid, e.g. ambient air. The second process is forced cooling in which the fluid is moved across the surface of a specific component to raise the convective heat transfer coefficient for the surface of the component thereby cooling the component faster than if the component was in static fluid. Most computer enclosures incorporate both heat dissipation processes to some degree. Both processes require the movement of air.  
         [0008]     It is well known to use fans or blowers to move air through computer enclosures to cool various components therein. Conventionally, such devices are placed in a front panel or a back panel of the computer enclosure. However, the presence of a power supply serves to create excess heat in the enclosure that tends to raise the operating temperature of other components in the enclosure. Accordingly, conventional computer chassis include a relatively large fan that is sized for the entire heat producing system, i.e. the power supply and the computer components in the chassis. The large fan wastes precious enclosure and panel space. Further, fans themselves generate heat and thus oversized fan generates excessive heat.  
         [0009]     It is known to take advantage of various ducts in computer chassis. For example, U.S. Pat. No. 6,094,345 discloses a computer enclosure having a duct that extends between external portions of the enclosure and includes an air intake that is open to internal portions of the enclosure. Air is drawn into an external intake and the internal intake for cooling the power supply. The air drawn in the internal intake has been heated by other components in the enclosure.  
         [0010]     U.S. Pat. No. 5,432,674 discloses a computer enclosure having a duct extending between the front and back panels of the enclosure. A fan forces air through the duct to cool a power supply. The duct includes an exhaust opening into an interior of the enclosure for cooling other components. Accordingly, the air used to cool the components has been heated by the power supply.  
       SUMMARY OF THE INVENTION  
       [0011]     It is an object of the invention to enhance cooling effects of electronic components.  
         [0012]     A first aspect of the invention is an electronics chassis including various active electronic components having various heat dissipation rates and operating tolerances. The chassis comprises an enclosure, a power supply housed in the enclosure, and at least one electronic component housed in the enclosure. An electronic component cooling system cools the electronic components. A power supply cooling system causes a fluid, such as air, to flow through an area surrounding the power supply to cool the power supply through convection by drawing fluid from an area external of the enclosure and exhausting fluid to an area external of the enclosure. The fluid is isolated from the components within the enclosure.  
         [0013]     A second aspect of the invention is a computer chassis comprising an enclosure, a power supply housed in the enclosure, and at least one computer component housed in the enclosure. A computer component cooling system cools the computer components. A power supply cooling system causes a fluid to flow through an area surrounding the power supply to cool the power supply through convection by drawing fluid from an area external of the enclosure and exhausting fluid to an area external of the enclosure. The fluid is isolated from the computer components within the enclosure. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0014]     The invention will be described through a preferred embodiment and the attached drawings in which:  
         [0015]      FIG. 1  is a top view of a chassis of the first preferred embodiment with a top panel removed;  
         [0016]      FIG. 2  is a front view of the chassis of  FIG. 1 ; and  
         [0017]      FIG. 3  is a top view of a chassis of the second preferred embodiment.  
         [0018]      FIG. 4  is a partially exploded, perspective view of another preferred embodiment without a front panel.  
         [0019]      FIG. 5  is a back view of the chassis of  FIG. 4  with the back panel removed for clarity of illustration; and  
         [0020]      FIG. 6  is a top view of another preferred embodiment, with the top panel removed for clarity of illustration. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0021]     In conventional computer chassis, the power supply fan typically exhausts directly to ambient, air that has already been heated by the computer components prior to being used to cool the power supply. Since this air came from around the computer components, it was heated above ambient prior to being used to cool the power supply. Therefore, the power supply fan must be capable of moving a large amount of air quickly since the heated air is not as effective for cooling as ambient air would be. In other words, known cooling techniques use a serial arrangement of cooling first the computer components with ambient air and then the power supply with the heated air that was used to cool the components. The invention uses a “parallel” technique for cooling both the components and the power supply with ambient air. Accordingly, the invention permits the cooling system to be separately optimized for both the power supply and the components. The particular temperature limits, heat generation, required air flow rates, geometries, space constraints, and other characteristics of the components and power supply are very different. Therefore, separate optimization yields a much more efficient cooling system.  
         [0022]      FIGS. 1 and 2  illustrate a first preferred embodiment of the invention. The preferred embodiments discussed herein relate to a computer chassis. However, the invention can be applied to any type of chassis having any type of electronic components. Computer chassis  10  includes enclosure  20  component bays  30 ,  32 , and  34 , motherboard  36 , and power supply  39 . Power supply  39  is housed in power supply casing  38 . Enclosure  20  of the preferred embodiment can be a standard rack mount enclosure, a desktop computer enclosure, a tower computer enclosure, or any other type of enclosure. As illustrated in  FIGS. 1 and 2 , enclosure  20  is constructed of front panel  22 , side panels  24 , back panel  26  bottom panel  27 , and top panel  28 .  
         [0023]     Bays  30 ,  32 , and  34  can house various devices such as DAT (digital audio tape) drives, hard drives, diskette drives, CD-ROM drives, DVD (digital video disk,, drives, and the like. Motherboard  36  includes plural memory module slots  50  (for supporting SDRAM memory modules, EDO memory modules, SIMMS memory modules, DIMMS memory modules, or the like), expansion card slots  52  (PCI, ISA, EISA, AGP, or the like), processor  54  and various other components and connectors in a known manner. Power supply  39  can be a standard power supply, or a custom power supply of any type.  
         [0024]     Fan assembly  40  is coupled to power supply casing  38  and includes a duct or other passage providing communication between power supply casing  38  and the exterior of enclosure  20  through an opening formed in back panel  26 . Duct  42  is coupled to power supply casing  38 , at a position substantially opposite fan assembly  40 , and provides communication between power supply casing  38  and the exterior of enclosure  20  through an opening formed in front panel  22  and covered by grill assembly  44 . Fan assembly  40 , duct  42 , and power supply casing  38  constitute a cooling means for power supply  39 . More specifically, fan assembly  40  exhausts a first fluid, ambient air in the preferred embodiment, out of power supply casing  38 , as indicated by the arrow. The air travels across power supply  39 , thus cooling power supply  39  through convection, as the air is replaced in power supply  39  by ambient air drawn into power supply casing  38  through grill assembly  44  and duct  42 . Alternatively, fan assembly  40  can be configured to blow air into power supply casing  38 , which air is exhausted to ambient through grill assembly  44  and duct  42 .  
         [0025]     Significantly, the fluid used for cooling power supply  39  is isolated from other components within the enclosure  20 . Accordingly, fan assembly  43  is provided in back panel  26  and includes a fan communicating with ambient through an opening in back panel  26  to exhaust air from enclosure  20  to ambient, as indicated by the arrow. Grill assembly  45  is provided over an opening in from panel  22  to permit a second fluid, also ambient air in the preferred embodiment, to be drawn into enclosure  20  by fan assembly  43  as fans assembly  43  exhausts air from enclosure  20  to ambient. Alternatively, fan assembly  43  can be configured to draw ambient air into enclosure  20  through grill assembly  45 . Fan assembly  43  and grill assembly  45  therefore serve as means for cooling the components. Note once again that the means for cooling power supply  39  are isolated from other portions of the interior of enclosure  20 . Therefore, the cooling means can be sized and tuned for power supply  39  to most efficiently cool power supply  39 .  
         [0026]      FIG. 3  illustrates a second embodiment that is similar to the first embodiment. However, in the second embodiment, duct  42  opens to grill assembly  44  in side panel  24 . Once again, the cooling air for power supply  39  is isolated from cooling air for other components. Other aspects of the second embodiment are the same or similar to the first embodiment and the various features of the embodiments can be combined.  
         [0027]      FIG. 4  illustrates another embodiment of the chassis  10  of the present invention. Aspects of this embodiment are the same or similar to the above embodiments. As shown in  FIG. 4 , enclosure  20  is divided by a ledge panel  25 . Power supply  39  rests upon ledge panel  25 . Top panel  28  can include perforations  47 . Referring to  FIG. 5 , a plurality of fan assemblies  40  for the cooling power supply are located at the back of enclosure  20  above ledge panel  25 . When assembled in enclosure  20 , power supply  39  is isolated from the other components via ledge  25 , side panels  24  and front panel (not shown) and back panel  26 . Fan assemblies  40 , top panel  28  with perforations  47  and ledge  25  form cooling means for power supply  39 . Fan assemblies  40  draw a first fluid, for example, ambient air, through perforations  47  and across power supply  39 , cooling the same through convection. The air is exhausted from the enclosure via fan assemblies  40  through back panel  26 . Although, not shown, fan assemblies  40  could be provided with grill assemblies, as in the other preferred embodiments. Also, as noted above, the flow of air can be reversed. Note that the position, size and number of perforations  47  can be configured to provide the desired flow of fluid across power supply  39 .  
         [0028]     The remaining devices are housed in bay  30  located below ledge panel.  25 . Although one bay  30  is illustrated, the area could be separated into individual bays as well. Communicating with bay  30  are fan assemblies  43 , the size and number of fan assemblies  43  being dependent upon the number of components housed within the enclosure. The components are cooled by a second fluid, also ambient air in the preferred embodiment. Openings in the front panel permit the second fluid to be drawn into bay  30  by fan assemblies  43  and exhausted from the back panel  26  via openings formed therein. The first and second cooling fluids are thus isolated. In a situation where plural chassis are stacked closely on top of one another, such as in a rack configuration, recessed portions can be defined in top panel  28  to permit air to flow freely into perforations  47 .  
         [0029]      FIG. 6  illustrates another preferred embodiment of the invention. The embodiment of  FIG. 6  is directed to a data storage device chassis, such as a chassis having additional hard drives to add storage to an existing network or computer device. Chassis  10  includes enclosure  20  component bays  30  and  32 , containing hard drives or other memory components in this embodiment, and two power supplies  39 . Power supplies  39  can be configured as redundant power supplies or each power supply  39  can power respective memory components. Power supplies  39  are disposed in power supply casing  38  which defines a channel through a central portion of enclosure  20 . Enclosure  20  of the preferred embodiment can be a standard rack mount enclosure, or any other type of enclosure. Enclosure  20  is constructed of front panel  22 , side panels  24 , back panel  26  bottom panel  27 , and a top panel (not shown in  FIG. 6 ).  
         [0030]     Fan assembly  45  is coupled to power supply casing  38  and includes a duct or other passage providing communication between power supply casing  38  and the exterior of enclosure  20  through an opening formed in back panel  26 . Fan assembly  45  and power supply casing  38  constitute a cooling means for power supplies  39 . More specifically, fan assembly  45  exhausts a first fluid, ambient air in the preferred embodiment, out of power supply casing  38 . The air travels across power supplies  39 , thus cooling power supplies  39  through convection, and the air is exhausted to ambient space out of a grill assembly or other opening in back panel  26 . Of course, as noted above, appropriate openings can be formed in enclosure  20  and power supply casing  38  to permit ambient air, from outside of enclosure  20  to replace the air exhausted from power supply casing  38 . Alternatively, fan assembly  45  can be configured to blow air into power supply casing  38 , which air is exhausted from power supply casing  38  through an appropriate opening in enclosure  20 .  
         [0031]     Significantly, the fluid used for cooling power supply  39  is isolated from other components within the enclosure  20 . Accordingly, fan assembly  43  is provided in back panel  26  and includes a fan communicating with ambient through an opening in back panel  26 . A grill assembly or other opening is provided in from panel  22  to permit a second fluid, also ambient air in this embodiment, to be drawn into enclosure  20  by fan assembly  43  as fan assembly  43  exhausts air through an opening in back panel  26 . Alternatively, fan assembly  43  can be configured to blow air into enclosure  20 . Fan assembly  43  therefore serve as means for cooling the memory components in bay  32 . Similarly, fan assembly  40  and appropriate openings in casing  20  can be provided to form a means for cooling the memory components in bay  30 . Note once again that the means for cooling power supplies  39  are isolated from other portions of the interior of enclosure  20 . In other words, there is not substantial mixing, within enclosure  20 , of the fluid for cooling the power supplies and the fluid for cooling the memory components.  
         [0032]     The invention can be applied to any type of electronic chassis, such as personal computers, servers, storage devices, audio/video devices, communications equipment, instrumentation, and the like. The power supply cooling means of the preferred embodiments includes fans, blowers, ducts and other passages. However, power supply the cooling means can take any form that moves fluid across the power supply to provide convective cooling. For example, the power supply cooling means can include blowers, pumps, solid state electronic motive devices, thermal devices which cause fluid motion through a temperature gradient, or the like. The intake and exhaust of the power supply cooling means can be at any position as long as such positions do not frustrate the substantial isolation between the various cooling means. Of course, it is impractical to hermetically seal components. Therefore, the term “isolated” as used herein refers to substantial isolation, but not necessarily complete isolation, which prevents substantial mixing between the various flows of cooling fluid. The fan assembly, or other device for moving cooling fluid, can be placed at any position, such as in a power supply housing, in a duct or other passage, external of these elements, inside the enclosure or external of the enclosure. Any combination of ducts, hoses, passages, baffles, devices for moving fluid, and other elements can be used to construct the power supply cooling means. The fluid used for cooling can be any fluid, such as ambient air, any other gas, liquids, or the like.  
         [0033]     It can be seen that isolation of the cooling means used for the power supply from cooling means used for other components permits the power supply cooling means to be designed and tuned for the heat dissipation characteristics of the power supply. Since these characteristics are significantly different from that of other components, the cooling system can be optimized. While the fluid flow paths for the cooling means are isolated, the same type of fluid can serve as the fluid flowing through each cooling means. For example, in the preferred embodiment, the first and second fluid are both ambient air. The isolated power supply cooling means may eliminate the need for forced convection cooling of other components. Therefore, the component cooling means may merely be accomplished through conduction and/or natural convection. It is often desirable to operate both cooling systems in a manner in which the exhaust of each system is remote from the intake of the systems to avoid recirculation of heated air into the enclosure.  
         [0034]     The invention can have any components in any configuration. For example, various power supplies, drives, motherboards switches and memory devices can be used. The invention can be used in any size of equipment requiring cooling. The enclosure can be rack mounted or free standing. The invention can include one or more power supplies having a common cooling means or separate cooling means.  
         [0035]     While the foregoing description includes many details and specificities, it is to be understood that these have been included for purposes of explanation only, and are not to be interpreted as limitations of the present invention. Many modifications to the embodiments described above can be made without departing from the scope of the invention, as set forth in the following claims and their legal equivalents.