Abstract:
An electronics chassis for containing and supporting electronic components having different operating temperatures includes a plurality of thermally conductive walls forming an enclosure. There is a first heat dissipator in at least one of the walls having an external heat dissipator and a second heat dissipator in at least one of the walls having an external heat dissipator. There is a thermal isolator positioned in at least one of the walls to provide thermal isolation between the heat dissipators, and the thermal isolator includes a thermally insulating material.

Description:
STATEMENT OF GOVERNMENT INTEREST 
     This invention was made with government support under FA8650-06-D-2621 awarded by the United States Air Force. The government has certain rights in the invention. 
    
    
     BACKGROUND 
     This invention relates to chassis for electronic components, and, more specifically, to chassis for electronic components that include heatsinks. 
     When electronic components such as motor controllers are operated, heat is generated. Because these components are designed to operate within certain temperature ranges, this heat must be dissipated from the system in order to promote efficient operation and avoid overheating. Therefore, heatsinks have been used to control the temperature of electronics. Heatsinks are generally comprised of thermally conductive material and are thermally connected to the electronic components. Heatsinks also include features that increase surface area, such as fins, which provide greater heat loss, through convection, to the ambient environment. Thereby, heat can be transferred from the electronic components and dissipated to the atmosphere. 
     It can be beneficial to attach more than one electronic component to a heatsink. Because a heatsink is a good thermal conductor, during operation of the electronic components the bulk of the heatsink, including the portion to which the components are mounted, will be at approximately the same temperature. This can be problematic if one of the electronic components requires a lower operating temperature than the other and/or if this component emits less heat than the other while, at the same time, the other component is dissipating much more heat and driving up the temperature of the heatsink. In this case the ambient temperature of the environment the components are located in can also cause overheating of the lower operating temperature components. 
     SUMMARY 
     According to one embodiment of the present invention, an electronics chassis for containing and supporting electronic components having different operating temperatures includes a plurality of thermally conductive walls forming an enclosure. There is a first heat generator in at least one of the walls having an external heat dissipator and a second heat generator in at least one of the walls having an external heat dissipator. There is a thermal isolator positioned in at least one of the walls to provide thermal isolation between the heat dissipators, and the thermal isolator includes a thermally insulating material. 
     In another embodiment, an electronic system includes an electronics chassis and two electronic components. The electronics chassis includes two electronic components generating heat that are separated by a thermal isolator, wherein one electronic component is mounted to one heat dissipator and the other electronic component is mounted to the other heat dissipator. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of an electronic system including an electronics chassis. 
         FIG. 2  is a perspective view of the electronic system with an electronics chassis in shadow. 
         FIG. 3  is a bottom view of the electronics chassis including two electronic components. 
         FIG. 4  is a cross-section view of the electronic system including a thermal isolator along line  3 - 3  in  FIG. 3 . 
     
    
    
     DETAILED DESCRIPTION 
     In  FIG. 1 , a perspective view of electronic system  10  is shown, including electronics chassis  12 . In  FIG. 2 , a perspective view of electronic system  10  with electronics chassis  12  in shadow. In  FIG. 3 , a bottom view of electronics chassis  12  is shown, including first electronic component  38  and second electronic component  40 .  FIGS. 1-3  will now be discussed simultaneously. 
     Electronic system  10  includes electronics chassis  12 , first electronic component  38 , second electronic component  40 , and cover plate  44 . In general, electronics chassis  12  is a unitary structure with top side  14 , shroud  16 , and flange  26 , and electronics chassis  12  is comprised of a thermally conductive material, such as aluminum. Top side  14  includes an aperture, into which first heat dissipator  30  is affixed. More specifically, first heat dissipator  30  is bonded to top side  14  by thermal isolator  34 . This is possible because thermal isolator  34  comprises a material with structural and adhesive properties, such as a non-thermally conductive elastomer (for example, a polyamide material). 
     In addition, top side  14  includes second heat dissipator  32 . Therefore, thermal isolator  34  is positioned between first heat dissipator  30  and second heat dissipator  32 . Heat dissipators  30 ,  32  have increased surface area on their respective top sides (opposite of mounting surface  42 , 43 ) because heat dissipators  30 ,  32  include fins  36 . Mounted to mounting surface  42  of top side  14  inside shroud  16  is first electronic component  38 . Mounted to mounting surface  43  of top side  14  inside shroud  16  is second electronic component  40 . Thereby, electronic components  38 ,  40  are thermally connected to heat dissipators  30 ,  32 , respectively. One skilled in the art can appreciate that although directional terms such as “top side”, “bottom side”, “underneath”, and “downward” are used to describe this invention, such terms are merely relational descriptors of the illustrated embodiments shown herein. 
     In the illustrated embodiment, shroud  16  extends perpendicularly downward from top side  14 , beyond electronic components  38 ,  40 . Shroud  16  comprises first side  18 , second side  20  which is adjacent to first side  18 , third side  22  which is adjacent to second side  20 , and fourth side  24 , which is adjacent to third side  22  and first side  18 . Attached around shroud  16  is flange  26  which includes a plurality of mounting holes  28 . Cover plate  44  is attached to flange  26  through mounting holes  28  to create a bottom side of electronic system  10 . 
     During operation of electronic component  38 , heat is generated and is transferred to heat dissipator  30  by conduction. During operation of electronic component  40 , heat is generated and is transferred to heat dissipator  32  by conduction. This heat is then dissipated to the atmosphere by convection. In the illustrated embodiment, first electronic component  38  is a high heat generating, high operating temperature rated electronic component whereas second electronic component  40  is a lower heat generating, lower operating temperature rated electronic component. Therefore during operation of first electronic component  38  emits more heat than second electronic component  40 . In practice, first heat dissipator  30  is at approximately 240° C. and second heat dissipator  32  is at approximately 180° C. during operation. This also means that first heat dissipator  30  dissipates more heat than second heat dissipator  32 . 
     The components and configuration of electronic system  10  as shown in  FIGS. 1-3  allow for electronics chassis  12  to be made from two pieces. In addition, heat can be eliminated from electronic components  38 ,  40  and transferred to the atmosphere. In addition,  FIGS. 1 and 2  show one embodiment of the present invention, to which there are alternatives. For example, there can be more than one first electronic component  38  mounted to first heat dissipator  30  and there can be more than one second electronic component  40  mounted to second heat dissipator  32 . For another example, the operating temperatures of first heat dissipator  30  and second heat dissipator  32  can vary from the embodiment listed above, in part due to the components used or the application of electronic system  10 . 
     In  FIG. 4 , a cross-section view of electronic system  10  is shown along line  3 - 3  in  FIG. 3 , including thermal isolator  34 . Shown in  FIG. 4  is the same embodiment as shown in  FIGS. 1-3  with additional features being visible. 
     As stated previously, during operation of electronic components  38 ,  40 , first heat dissipator  30  is at a greater temperature than second heat dissipator  32 . This is possible because thermal isolator  34  substantially prevents heat transfer between first heat dissipator  30  and second heat dissipator  32 . This is possible because thermal isolator  34  comprises a material with low thermal conductivity such as a non-thermally conductive elastomer (for example, a polyamide material). 
     In other words, thermal isolator  34  acts as a thermal isolator to isolate the higher operating temperature component(s)  38  from the lower operating temperature component(s)  40 . In the illustrated embodiment, thermal isolator  34  forms a thermal isolation ring around higher operating temperature component  38 . 
     The components and configuration of electronic system  10  as shown in  FIG. 3  allow for electronic components  38 ,  40  to be protected by electronics chassis  12 . Furthermore, heat transfer can occur from first electronic component  38 , through first heat dissipator  30 , and to the atmosphere. But heat transfer from first heat dissipator  30  to second heat dissipator  32  is impeded, which prevents first electronic component  38  from heating up (and possibly overheating) second electronic component  40 . 
     It should be recognized that the present invention provides numerous benefits and advantages. For example, multiple electronic components with different operating temperatures can be mounted to the same chassis substantially without having heat transfer occur between the electronic components. 
     While the invention has been described with reference to an exemplary embodiment(s), it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment(s) disclosed, but that the invention will include all embodiments falling within the scope of the appended claims.