Abstract:
An apparatus for removing heat from heat generating elements is disclosed. The apparatus is a thermal management system having a thermal distribution assembly in either one of or both of conductive and radiative communication with heat generating elements. The thermal distribution assembly has thermal zones, each of which is associated with at least one heat generating element. The thermal distribution assembly includes a heat spreading frame and a heat conducting frame. Heat passes from the heat generating elements to the heat conducting frame and then to the heat spreading frame, from which the heat is removed via convection.

Description:
This application is a continuation of U.S. patent application No. 10/462,864, filed Jun. 16, 2003, now U.S. Pat. No. 6,757,162, which is a continuation application of U.S. patent application No. 09/996,862, filed Nov. 27, 2001 (now U.S. Pat. No. 6,594,147), which is a continuation application of U.S. patent application No. 09/411,062, filed Oct. 4, 1999 (now U.S. Pat. No. 6,362,956). 

   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates generally to heat removal devices, and more specifically to heat removal devices for electronic components. 
   2. Background Information 
   Electronic components are capable of generating undesirable levels of heat during normal use. For example, in some personal computers, the microprocessor can generate enough heat to damage the microprocessor if at least some of the heat is not removed from the microprocessor. Furthermore, personal computers and other electronic systems often have a number of heat producing components which are located in an enclosed area and are in close proximity to one another. The total heat generated by such situated heat producing components can reach high enough levels to damage the entire system if the heat is not dissipated within the enclosed area or removed from the components. 
   Many existing heat removal devices attempt to remove heat from electronic components using forced convection. A common example of a forced convection device is a fan. Some electronic systems use one large fan to cool all of the heat producing components within the system. Other electronic systems have individual fans for each heat producing component. Still other electronic systems have both one main fan and individual component fans. However, fans can be problematic because they often generate unacceptable levels of noise and require their own power to run. In addition, because fans incorporate moving parts, they are susceptible to mechanical failure. By the time a defective fan is detected, the previously cooled component could have already overheated and been damaged. 
   Other existing heat removal systems attempt to remove heat from electronic components using natural convection. Conventionally, this is effected by directly attaching the sources of heat generation to heat sinks. However, these heat sinks are of necessity large relative to the heat sources, and their size places undesirable constraints upon the design of a product with high heat generation density. 
   Thus, to help ensure the continuing safe performance of heat generating electronic components, it is desirable to remove heat from such components in a quiet, efficient and reliable manner. Particularly, it is desirable to effect high density and efficient heat removal through multi-purpose components incorporated into a unified thermal management system. 
   SUMMARY OF THE INVENTION 
   The present invention provides a thermal management system for distributing and removing heat from heat generating elements. The system also provides functionality for structural support and EMI suppression, thereby providing a more efficient, compact and cost effective design. 
   In one embodiment of the present invention, the thermal management system has a thermal distribution assembly which is in conductive and/or radiative communication with heat generating elements. The thermal distribution assembly has thermal zones, each of which is associated with at least one heat generating element. 
   In another embodiment of the present invention, the thermal distribution assembly includes a heat spreading frame and a heat conducting frame in conductive contact with the heat spreading frame. The heat conducting frame removes heat from heat generating elements via conduction and/or radiation, and the heat passes to the heat spreading frame. Natural convection then removes the heat from the heat spreading frame. 
   In another embodiment of the present invention, the thermal management system also includes a main body which houses the heat generating elements. The main body has an inlet and an outlet to facilitate the convective flow of air through the main body such that the heat generating elements are sufficiently cooled. 
   Additional features and benefits of the present invention will become apparent upon review of the following description. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Various embodiments of the present invention will be described in detail with reference to the following drawings in which like reference numerals refer to like elements. The present invention is illustrated by way of example and not limitation in the accompanying figures. 
       FIG. 1  shows one part of a thermal distribution assembly in accordance with the teachings of the present invention. 
       FIGS. 2A–2C  show a top angled exploded view of the part of the thermal distribution assembly shown in  FIG. 1 . 
       FIGS. 2D–2F  show an upside down exploded view of the part of the thermal distribution assembly shown in  FIG. 1 . 
       FIG. 3  shows a side cross-sectional view of another embodiment of a part of a thermal distribution assembly in accordance with the teachings of the present invention. 
       FIG. 4A  shows a front angled view of a housing in accordance with the teachings of the present invention. 
       FIG. 4B  shows a rear angled view of the housing shown in  FIG. 4A . 
       FIG. 5A  shows a front and top cut-away view of a housing to show a thermal management system in accordance with the teachings of the present invention. 
       FIG. 5B  shows a side cut-away view of the housing shown in  FIG. 5A . 
       FIG. 6  shows a side cross-sectional view of a top portion of a housing in accordance with the teachings of the present invention. 
   

   DETAILED DESCRIPTION 
   The following description provides embodiments of the present invention. However, it will be appreciated that other embodiments of the present invention will become apparent to those of ordinary skill in the art upon examination of this description. Thus, the present description and accompanying drawings are for purposes of illustration and are not to be used to construe the invention in a restrictive manner. 
     FIG. 1  illustrates one part of a thermal distribution assembly in accordance with the teachings of the present invention. A printed circuit board  102  is coupled to one side of a heat conducting frame  106 . Another printed circuit board  104  is coupled to the other side of heat conducting frame  106 . Typically, printed circuit boards  102  and  104  each have heat producing elements attached to them (see  FIGS. 2C and 2D , for example). The heat producing elements can be microprocessors, power supplies or any other commonly known heat producing elements. Heat sinks  108   a  and  108   b  are coupled to and in conductive communication with heat producing elements on printed circuit board  102 . Heat sinks  108   a  and  108   b  help dissipate heat generated by any heat producing components on printed circuit board  102  which might heat up printed circuit boards  102  and  104 . 
   In one embodiment of the present invention, not all of the components are in physical contact with heat conducting frame  106 ; such components can radiate heat to heat conducting frame  106 . The heat producing components on circuit boards  102  and  104  that are in physical contact with heat conducting frame  106  conduct heat to heat conducting frame  106 ; such components can also radiate heat to heat conducting frame  106 . It is appreciated that heat conducting frame  106  can be any suitable conductive material, such as metal. Furthermore, although two circuit boards are shown, it is appreciated that the present invention is also applicable to electronic systems with only one circuit board. 
   The following discussion is made with reference to  FIGS. 2A–2F , which show two exploded views of the portion of the thermal distribution assembly shown in  FIG. 1 . A microprocessor  110  is attached to one side of printed circuit board  104 . A power supply  113  is attached to the other side of printed circuit board  104 . A local heat conducting frame  112  coupled to board  104  is disposed around and in conductive communication with power supply  113 . Local heat conducting frame  112  has its own thermal zone because much of its surface area is in physical contact with power supply  113 , which is generating heat that is transferred to frame  112 . Because much of the heat generated by power supply  113  is conducted directly to frame  112 , a localized temperature can exist at frame  112 . Similarly, the area of frame  106  around microprocessor  110  can be considered to have its own thermal zone with a particular localized temperature. 
   In one embodiment of the present invention, frame  112  is in conductive communication with frame  106  to help remove the heat generated by power supply  113 . Some of the heat generated by microprocessor  110  is removed via conduction by a heat sink  114 , which is in direct physical contact with microprocessor  110  when circuit board  104  is coupled to frame  106 . Heat sink  114  is typically coupled to frame  106 . Alternatively, heat sink  114  is integrally formed with frame  106 . Heat sink  114  may be formed of a composite of materials to offer a desirable mixture of thermal conductivity and mechanical compliance. In any case, heat sink  114  helps to spread the heat generated by microprocessor  110  to frame  106 . 
     FIG. 3  shows a side cross-sectional view of a part of a thermal distribution assembly similar to that which is shown in  FIG. 1 . A printed circuit board  302  is coupled to one side of a conductive divider  306 . A printed circuit board  304  is coupled to the other side of conductive divider  306 . Heat sink  308  is coupled to and in conductive communication with board  302  to help remove heat from board  302 . A microprocessor  310  is coupled to board  304 . Microprocessor  310  is in direct physical contact with a local heat spreader  314 , similar to heat sink  114 , which is attached to or integrally formed with conductive divider  306 . Heat spreader  314  is made of a conductive material or a composite of materials to offer a desirable mixture of thermal conductivity and mechanical compliance. Thus, microprocessor  310  is in conductive communication with conductive divider  306 . 
   A local heat conducting frame  312  is thermally isolated from conductive divider  306  by insulative material  316 . In one embodiment, local heat conducting frame  312  houses and is in conductive communication with a heat generating component such as a DVD drive, CD drive, hard drive or other storage media. Thus, frame  312  can act as a heat distributor and heat sink to facilitate convective heat transfer. In one embodiment of the present invention, heat generating components on boards  302  and  304  radiate heat to conductive divider  306  as shown in area  318  on board  302 . 
     FIGS. 4A and 4B  illustrate front and rear angled views, respectively, of a housing  400  in accordance with the teachings of the present invention. Housing  400  encloses a number of heat generating components (not shown) which form an electronic system. Housing  400  has a top portion  401   a  and a bottom portion  401   b . In one embodiment, top portion  401   a  and bottom portion  401   b  are separate pieces of housing  400  which are fitted together to form housing  400 . A handle  402  is formed in top portion  401   a  of housing  400  to allow a person to pick up housing  400 . A circular outlet vent  404  is formed in top portion  401   a  around handle  402 . In one embodiment, outlet vent  404  and handle  402  are integrally formed with each other to constitute a separate piece which is coupled to top portion  401   a . A plurality of holes  406  is formed in outlet vent  404  to facilitate the escape of heat generated by heat generating components located inside housing  400 . 
   A concavity  412  is formed in housing  400  to allow a person to place his or her fingers around handle  402  and comfortably grasp handle  402 . Concavity  412  also serves to deflect air flow from within housing  400  toward outlet vent  404 . An inlet vent  408  is formed in bottom portion  401   b  of housing  400 . A plurality of holes  410  is formed in inlet vent  408  to facilitate a convective air path from inlet vent  408  through the inside of housing  400  to outlet vent  404 . In a preferred embodiment of the present invention, natural convection provides the flow of air from inlet vent  408  through the inside of housing  400  to outlet vent  404 . However, it is appreciated that the present invention can be used in conjunction with a fan or other cooling device that provides forced convection. 
     FIGS. 5A and 5B  illustrate a front and top cut-away view and a side cut-away view, respectively, of a housing similar to that shown in  FIGS. 4A and 4B . A thermal management system according to the present invention is shown within the housing. A printed circuit board  502  is coupled to the top of a heat conducting divider  506 . A printed circuit board  504  is coupled to the bottom of heat conducting divider  506 . Heat sinks  508   a  and  508   b  are coupled to board  502  to help remove heat from board  502 . A heat spreading frame  510  is coupled to and in conductive communication with divider  506 . Heat spreading frame  510  is disposed around the sides and rear of boards  502 ,  504  and  506 . A plurality of air vents  511  is formed in frame  510 . Air vents  511  can be formed at regular intervals in frame  510  or in any pattern that facilitates air flow around frame  510  and within the spaces between frame  510  and the components and heat sinks adjacent to frame  510 . In one embodiment, frame  510  is made of plastic. In another embodiment, frame  510  helps form a housing, including lower housing  512 , to fully enclose the components of a computer system. Frame  510  can be one continuous piece or several pieces coupled together. 
   A power supply  514  is coupled to board  504 . A local heat conducting frame  516  is disposed around and in conductive communication with power supply  514 . An EMI shield  520  further encloses power supply  514  and frame  516 . In one embodiment, frame  516  is coupled to board  504  and in conductive communication with divider  506 . In a preferred embodiment of the invention, divider  506  in combination with frame  516  and frame  510  provide structural support for the system. A convective air flow  518  from inlet vents (not shown) in the bottom of a lower housing  512  help remove heat from heat generating components, such as power supply  514 , frames  502 ,  504 ,  506  and  510 , and heat sinks  508   a  and  508   b . It should be noted that heat sinks  508   a  and  508   b  and heat producing elements such as power supply  514  are located near the periphery of the housing to facilitate heat removal by being closer to air flow  518  flowing up, around and through frame  510 . It should be further noted that air flow  518  follows a generally upward path because air flow  518  gradually acquires heat from the heat sources located within the housing. 
     FIG. 6  illustrates a side cross-sectional view of a top housing  600  that can be used with the embodiments of the present invention shown in  FIG. 4A ,  4 B or  5 . An outlet vent  604  is formed in top housing  600 . In one embodiment, outlet vent  604  comprises a plurality of holes which permit the escape of air from within top housing  600 . Outlet vent  604  surrounds a handle  602  formed in top housing  600  in a manner similar to that shown in  FIGS. 4A and 4B . In one embodiment, outlet vent  604  is integrally formed with handle  602  to form a piece separate from top housing  600 ; the piece is secured to top housing  600  in a manner suitable to allow a person to use handle  602 . A concavity  606  is formed in top housing  600  below handle  602  to allow a person to place his or her fingers around handle  602  and comfortably grasp handle  602 . Concavity  606  also serves to direct a convective air flow  608  from within top housing  600  toward outlet vent  604 . By deflecting air flow  608 , which is typically heated, toward outlet vent  604 , concavity  606  facilitates the removal of heated air via outlet vent  604  and prevents heated air from heating handle  602  to uncomfortably high temperatures. 
   In the foregoing detailed description, the apparatus and method of the present invention have been described with reference to specific exemplary embodiments. However, it will be evident that various modifications and changes may be made without departing from the broader scope and spirit of the present invention. The present specification and figures are accordingly to be regarded as illustrative rather than restrictive.