PATENT DOCUMENT

Publication Number: US-10948953-B2
Application Number: US-201916512023-A
Country: US
Kind Code: B2

Title: Optimized vent walls in electronic devices

Abstract:
The disclosed embodiments related to a component for use in a portable electronic device. The component includes a wall of the portable electronic device, containing an intake zone that includes a set of intake vents. The wall also includes an exhaust zone containing a set of exhaust vents.

Claims:
What is claimed is: 
     
       1. A portable electronic device, comprising:
 a fan disposed within the portable electronic device; 
 a bottom case extending about the fan, the bottom case having a wall characterized by: 
 a first set of vents defined in the wall of the bottom case, 
 a second set of vents defined in the wall of the bottom case proximate the fan and adjacent the first set of vents; 
 a housing comprising a clutch barrel rotatable with respect to the bottom case and positioned proximate the second set of vents, wherein the clutch barrel defines a flow path from the second set of vents about the clutch barrel; and 
 a top case coupled with the bottom case and providing:
 a first positional alignment of the housing with the bottom case in which the housing is in closed contact with the top case, and 
 a second positional alignment of the housing with the bottom case in which the housing is separated from the top case, wherein, when in the second positional alignment, the clutch barrel defines a plurality of flow paths. 
 
 
     
     
       2. The portable electronic device of  claim 1 , further comprising a heat pipe extending between the fan and the second set of vents. 
     
     
       3. The portable electronic device of  claim 2 , further comprising a heat sink contacting the heat pipe. 
     
     
       4. The portable electronic device of  claim 1 , wherein, when in the first positional alignment, the clutch barrel defines a single flow path from the second set of vents. 
     
     
       5. The portable electronic device of  claim 4 , wherein the single flow path extends towards a base of the bottom case. 
     
     
       6. The portable electronic device of  claim 1 , wherein the plurality of flow paths include a first flow path extending along the clutch barrel and the top case, and a second flow path extending along the clutch barrel and the bottom case. 
     
     
       7. The portable electronic device of  claim 1 , wherein the housing incorporates a display, and wherein the plurality of flow paths direct fluid flow to avoid the display. 
     
     
       8. The portable electronic device of  claim 1 , wherein the fan is a first fan, wherein the portable electronic device further comprises a second fan, wherein the first fan is positioned proximate a first portion of the second set of vents, and wherein the second fan is positioned proximate a second portion of the second set of vents. 
     
     
       9. The portable electronic device of  claim 1 , wherein the portable electronic device comprises a laptop computer. 
     
     
       10. A portable electronic device, comprising:
 a top case; 
 a bottom case coupled with the top case to define an internal volume; 
 a fan disposed in the bottom case, wherein the bottom case includes a wall characterized by:
 a first set of vents defined in the wall of the bottom case, 
 two second sets of vents defined in the wall of the bottom case proximate the fan, wherein the first set of vents is located between the two second sets of vents; and 
 
 a housing comprising a clutch barrel rotatable with respect to the bottom case and positioned proximate the second set of vents, wherein the clutch barrel at least partially extends about a hinge rotatably coupling the housing with the bottom case, wherein the hinge provides a first positional alignment of the housing with the bottom case in which the housing is in closed contact with the top case, and wherein, when in the first positional alignment, the clutch barrel defines a single flow path from the two second sets of vents. 
 
     
     
       11. The portable electronic device of  claim 10 , further comprising a heat generating component positioned within the internal volume, the heat generating component thermally coupled with a heat distribution assembly configured to distribute heat from the heat generating component towards the two second sets of vents. 
     
     
       12. The portable electronic device of  claim 11 , wherein the distributed heat is expressed from the two second sets of vents and directed along the clutch barrel along the bottom case. 
     
     
       13. The portable electronic device of  claim 12 , wherein the distributed heat is further directed along the clutch barrel along the top case. 
     
     
       14. The portable electronic device of  claim 10 , further comprising two fans, each fan positioned proximate a second set of vents of the two second sets of vents. 
     
     
       15. A portable electronic device, comprising:
 a housing comprising a rotatable display and a clutch barrel defining airflow paths from the portable electronic device; and 
 a bottom case at least partially defining an internal volume of the portable electronic device in which a fan is disposed, wherein the internal volume houses a heat generating component, and wherein the bottom case includes a wall characterized by:
 a first set of vents defined in the wall of the bottom case, and 
 two second set of vents defined in the wall of the bottom case and defined at an angle within the wall of the bottom case, wherein the first set of vents is located between the two second sets of vents, and wherein a first positional alignment of the housing with the bottom case includes the housing in closed contact with a top case, and wherein, when in the first positional alignment, the clutch barrel defines a single flow path from the two second sets of vents. 
 
 
     
     
       16. The portable electronic device of  claim 15 , wherein the clutch barrel defines an airflow path from the second set of vents directed away from the rotatable display.

Description:
RELATED APPLICATIONS 
     The instant application is a continuation of, and hereby claims priority to, U.S. patent application Ser. No. 15/904,743, titled “Optimized Vent Walls in Electronic Devices,” which was filed on 26 Feb. 2018, which is a continuation of U.S. patent application Ser. No. 14/625,098, titled “Optimized Vent Walls in Electronic Devices,” which was filed on 18 Feb. 2015, which is a divisional of, and hereby claims priority to, U.S. patent application Ser. No. 13/627,231, titled “Optimized Vent Walls in Electronic Devices,” which was filed on 26 Sep. 2012. U.S. patent application Ser. No. 13/627,231 claims priority to U.S. provisional application No. 61/657,505, titled “Optimized Vent Walls in Electronic Devices,” which was filed on 8 Jun. 2012; U.S. provisional application No. 61/657,500, titled “Heat Exchanger with Dual Bypass,” which was filed on 8 Jun. 2012; and U.S. provisional application No. 61/657,492, titled “Fluid-Flow Bifurcation Using Clutch Barrel,” which was filed on 8 Jun. 2012. Each of these applications is herein incorporated by reference in its entirety for all purposes. 
    
    
     BACKGROUND 
     Field 
     The disclosed embodiments relate to techniques for facilitating heat transfer in electronic devices. More specifically, the disclosed embodiments relate to optimized vent walls in electronic devices. 
     Related Art 
     A modern portable electronic device typically contains a set of tightly packed components. For example, a laptop computer may include a keyboard, display, speakers, touchpad, battery, buttons, processor, memory, internal storage, and/or ports in an enclosure that is less than one inch thick, 8-11 inches long, and 12-16 inches wide. Moreover, most components in the portable electronic device generate heat, which must be dissipated to enable safe use of the portable electronic device and improve long-term reliability. For example, heat generated by components in a laptop computer may be transferred away from the components and out of the laptop computer to prevent damage to the components and increase user comfort and safety while operating the laptop computer. 
     However, heat-dissipation mechanisms for portable electronic devices generally involve the use of additional parts and/or materials. For example, heat sinks, cooling fans, heat pipes, thermal spreaders, and/or vents may be used to dissipate heat from components in a laptop computer. Such heat-dissipating parts and/or materials may take up space within the portable electronic devices and may add to the cost of the portable electronic devices. 
     In addition, the heat-dissipating parts and/or materials result in exhaust flows that often contain heated air. This heated air can impinge on a display in a portable electronic device, and may increase the temperature of the display and/or may create temperature gradients on the display. The optical properties of displays that contain liquid-crystal materials are often a function of temperature. Therefore, the temperature changes and/or gradients can cause color changes and other visual artifacts that can degrade the quality of the displayed image. 
     Hence, space-efficient designs for portable electronic devices may be facilitated by more efficient and/or smaller heat-dissipation mechanisms in the portable electronic devices, and may reduce temperature changes and/or gradients on displays. 
     SUMMARY 
     The disclosed embodiments provide a component for use in a portable electronic device. The component includes a wall of the portable electronic device, containing an intake zone that includes a set of intake vents directed at a first angle toward one or more heat-generating components of the portable electronic device. The wall also includes an exhaust zone containing a set of exhaust vents directed at a second angle out of the portable electronic device. 
     In some embodiments, the wall also includes one or more obstructed vents between the intake zone and the exhaust zone. 
     In some embodiments, material adjacent to an exhaust vent from the exhaust vents is removed to reduce a temperature of a hot spot in the material during the transfer of exhaust out of the portable electronic device. 
     In some embodiments, the temperature of the hot spot is further reduced by maintaining a thickness of the material between the exhaust vent and one or more of the intake vents. 
     In some embodiments, the material is removed using a T-cut. 
     In some embodiments, the portable electronic device is a laptop computer. 
     In some embodiments, the wall corresponds to a rear wall that is integrated into a top case of the laptop computer. 
     In some embodiments, the second angle directs exhaust out of the laptop computer to avoid a display of the laptop computer. 
     Another embodiment provides a portable electronic device that includes an external housing with a top case and a bottom case that each has inner surfaces that define an internal cavity. The internal cavity includes at least an integrated circuit that generates heat during operation of the portable electronic device. Moreover, a heat exchanger in the internal cavity, which is thermally coupled to the integrated circuit, transfers the thermal power away from the integrated circuit. Furthermore, a forced-fluid driver in the internal cavity drives a fluid flow through the heat exchanger and out of the portable electronic device via a fluid-flow port in the external housing so that, during operation of the portable electronic device, the thermal power is transported away from the heat exchanger. Note that there are vertical gaps between the heat exchanger and the top case and the bottom case so that, during operation of the portable electronic device, additional fluid flows through the vertical gaps are located above and below the fluid flow. 
     In some embodiments, the heat exchanger includes convective-cooling fins and/or the forced-fluid driver includes a fan. Moreover, the fluid flow and the additional fluid flows may include a gas, such as air. 
     After passing through the heat exchanger during operation of the portable electronic device, a temperature of the fluid flow may be higher than those of the additional fluid flows. Furthermore, the fluid-flow port may have a length, and mixing of the additional fluid flows and the fluid flow may be at most partial over the length. 
     In some embodiments, the interval cavity includes a heat pipe thermally coupled to the integrated circuit at an evaporator region of the heat pipe. During operation of the portable electronic device, the heat pipe may transport the thermal power from the evaporator region to a condenser region of the heat pipe, and the heat exchanger may be thermally coupled to the heat pipe at the condenser region. 
     Additionally, the internal cavity may include a duct, located above the heat exchanger and mechanically coupled to the top case, which guides one of the additional fluid flows over a top of the heat exchanger. 
     Another embodiment provides a portable electronic device that includes the external housing, the integrated circuit, the heat exchanger and the forced-fluid drive. However, in addition to or instead of the vertical gaps, there is a gap between the heat exchanger and a wall of the internal cavity in a horizontal plane of the heat exchanger so that an additional fluid flow flows through the gap. Once again, the fluid flow may have a higher temperature than that of the additional fluid flow, and mixing of the additional fluid flow and the fluid flow may be at most partial over the length of the fluid-flow port. Furthermore, the portable electronic device may include: a component adjacent to the wall of the internal cavity, where the gap is between the heat exchanger and the component; and a duct, located in the gap, which guides the additional fluid flow over the component. 
     Another embodiment provides a method for cooling a cavity in a portable electronic device. During operation of the portable electronic device, the forced-fluid driver generates the fluid flow through the heat exchanger in the cavity so that thermal power associated with operation of the integrated circuit in the cavity is transported out of the cavity. Moreover, the forced-fluid driver generates additional fluid flows through the vertical gaps between the heat exchanger and the walls of the cavity so that the additional fluid flows through the vertical gaps are located above and below the fluid flow. 
     Another embodiment provides a portable electronic device that includes an external housing with a top case and a bottom case that each has inner surfaces that define an internal cavity. The internal cavity includes at least an integrated circuit that generates heat during operation of the portable electronic device. Moreover, the portable electronic device includes a rotatable display that is mechanically coupled to the external housing by a hinge, where the rotatable display has a configurable angular position relative to a plane of the top case. Furthermore, the portable electronic device includes a housing (such as a clutch barrel) that at least partially encloses the hinge along an axis of rotation of the rotatable display. During operation of the portable electronic device, a fluid-flow port in the external housing directs fluid flows out of the internal cavity. These fluid flows include a central fluid flow sandwiched between two additional fluid flows, where the central fluid flow has a higher temperature than those of the additional fluid flows. Additionally, the housing directs the central fluid flow away from the rotatable display over a range of angular positions of the rotatable display. 
     In some embodiments, the portable electronic device includes a forced-fluid driver in the internal cavity that generates the fluid flows. For example, the forced-fluid driver may include a fan. 
     Moreover, the range of angular positions may include approximately 0° and approximately between 90° to 110°. When the angular position is approximately 0°, the housing may direct the central fluid flow out of the portable electronic device. Furthermore, when the angular position is approximately between 90° and 110°, the housing may direct the central fluid flow into the housing, and may direct one of the additional fluid flows to the rotatable display and another of the additional fluid flows out of the portable electronic device. 
     In some embodiments, during operation of the portable electronic device, the housing may reduce a flow impedance of another fluid flow in another fluid-flow port into the portable electronic device. Additionally, during operation of the portable electronic device, the housing may direct a portion of the other fluid flow over at least the integrated circuit. 
     Note that the fluid flow and the additional fluid flows may include a gas, such as air. 
     Another embodiment provides a method for cooling a cavity in a portable electronic device. During operation of the portable electronic device, the forced-fluid driver generates the fluid flows through the fluid-flow port so that thermal power associated with operation of at least an integrated circuit in the cavity is transported out of the cavity, where the fluid flows include the central fluid flow sandwiched between two additional fluid flows, and the central fluid flow has the higher temperature than those of the additional fluid flows. Moreover, the housing directs the central fluid flow away from the rotatable display in the portable electronic device that at least partially encloses the hinge that facilitates the configurable angular position of the rotatable display relative to the plane of the top case in the portable electronic device. Note that the central fluid flow is directed away from the rotatable display over the range of angular positions of the rotatable display. 
     In some embodiments, the housing reduces the flow impedance of the other fluid flow in the other fluid-flow port into the portable electronic device. Additionally, the housing may direct the portion of the other fluid flow over at least the integrated circuit. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         FIG. 1  is a block diagram illustrating a bottom view of a portable electronic device in accordance with an embodiment of the present disclosure. 
         FIG. 2  is a block diagram illustrating a cross-sectional view of a system for facilitating heat transfer in a portable electronic device in accordance with an embodiment of the present disclosure. 
         FIG. 3  is a block diagram illustrating a sectional view of a system for facilitating heat transfer in a portable electronic device in accordance with an embodiment of the present disclosure. 
         FIG. 4  is a block diagram illustrating a side view of a thermal stage in accordance with an embodiment of the present disclosure. 
         FIG. 5  is a block diagram illustrating a wall in a portable electronic device in accordance with an embodiment of the present disclosure. 
         FIG. 6  is a block diagram illustrating a rear view of a set of intake and exhaust zones in a portable electronic device in accordance with an embodiment of the present disclosure. 
         FIG. 7  is a block diagram illustrating a cross-sectional view of a portable electronic device in accordance with an embodiment of the present disclosure. 
         FIG. 8  is a block diagram illustrating a cross-sectional view of a portable electronic device in accordance with an embodiment of the present disclosure. 
         FIG. 9  is a block diagram illustrating a gasket in a portable electronic device in accordance with an embodiment of the present disclosure. 
         FIG. 10  is a block diagram illustrating a flexible portion of a gasket in accordance with an embodiment of the present disclosure. 
         FIG. 11  is a block diagram illustrating a flexible portion of a gasket in accordance with an embodiment of the present disclosure. 
         FIG. 12  is a flow chart illustrating a method of facilitating heat transfer in a portable electronic device in accordance with an embodiment of the present disclosure. 
         FIG. 13  is a flow chart illustrating a method of facilitating heat transfer in a portable electronic device in accordance with an embodiment of the present disclosure. 
         FIG. 14  is a flow chart illustrating a method of assembling a portable electronic device in accordance with an embodiment of the present disclosure. 
         FIG. 15  is a block diagram illustrating a side view of a portable electronic device in accordance with an embodiment of the present disclosure. 
         FIG. 16  is a block diagram illustrating a top view of a portable electronic device in accordance with an embodiment of the present disclosure. 
         FIG. 17  is a block diagram illustrating a top view of a portable electronic device in accordance with an embodiment of the present disclosure. 
         FIG. 18  is a block diagram illustrating a side view of the portable electronic device of  FIG. 17  in accordance with an embodiment of the present disclosure. 
         FIG. 19  is a block diagram illustrating a side view of the portable electronic device of  FIG. 17  in accordance with an embodiment of the present disclosure. 
         FIG. 20  is a block diagram illustrating a side view of the portable electronic device of  FIG. 17  in accordance with an embodiment of the present disclosure. 
         FIG. 21  is a flowchart illustrating a method for cooling a cavity in the portable electronic device of  FIG. 15  in accordance with an embodiment of the present disclosure. 
         FIG. 22  is a flowchart illustrating a method for cooling a cavity in the portable electronic device of  FIG. 16  in accordance with an embodiment of the present disclosure. 
         FIG. 23  is a flowchart illustrating a method for cooling a cavity in the portable electronic device of  FIGS. 17-20  in accordance with an embodiment of the present disclosure. 
         FIG. 24  is a block diagram illustrating a portable electronic device in accordance with an embodiment of the present disclosure. 
     
    
    
     Note that like reference numerals refer to corresponding parts throughout the drawings. Moreover, multiple instances of the same part are designated by a common prefix separated from an instance number by a dash. 
     DETAILED DESCRIPTION 
       FIG. 1  shows a bottom view of a portable electronic device  100 , such as a laptop computer, with the bottom of the enclosure of portable electronic device  100  removed. Within portable electronic device  100 , a number of components may be used to cool heat-generating components such as central-processing units (CPUs), graphics-processing units (GPUs), and/or video memory. 
     First, portable electronic device  100  may include a set of fans  102 - 104  for expelling heat generated by the heat-generating components outside portable electronic device  100 . Fans  102 - 104  may utilize a set of intake and exhaust vents along a wall  118  of portable electronic device  100  to draw in cooler air from outside portable electronic device  100 , circulate the air around the interior of portable electronic device  100  to dissipate heat from the heat-generating components, and expel the heated air out of portable electronic device  100 . 
     Portable electronic device  100  may also include a heat pipe  106  that conducts heat away from one or more of the heat-generating components toward the flow of exhaust from fans  102 - 104 . For example, heat pipe  106  may be a sealed pipe of a thermally conductive material, such as copper, filled with a working fluid such as: water, ethanol, acetone, sodium, and/or mercury in a partial vacuum. The working fluid may evaporate to vapor at the thermal interface with a heat-generating component closer to the center of heat pipe  106 , migrate to an end of heat pipe  106  that is cooled by a fan (e.g., fans  102 - 104 ), and condense back into liquid after the heat is removed by the fan. A sintered material (e.g., metal powder) in the interior of heat pipe  106  may then exert capillary pressure on the condensed liquid, conducting the liquid back to the heated portion of heat pipe  106  for subsequent transfer of heat away from the heat-generating component. 
     To further facilitate heat dissipation from the heat-generating component, a thermal stage  108  may apply a spring force between heat pipe  106  and the heat-generating component. For example, thermal stage  108  may be bonded to heat pipe  106  using a solder and fastened to a surface within portable electronic device  100  using a set of fasteners  110 - 116  to increase the amount of heat transferred along a thermal interface between the heat-generating component and heat pipe  106 . 
     In one or more embodiments, heat-dissipation mechanisms and/or components in portable electronic device  100  may include a number of characteristics and/or features that increase the transfer of heat away from the heat-generating components and/or facilitate efficient use of space within portable electronic device  100 . First, fasteners  110 - 116  may both fasten thermal stage  108  to a surface within portable electronic device  100  and create a thermal gap between heat pipe  106  and the enclosure of portable electronic device  100 , as discussed below with respect to  FIG. 2 . Second, thermal stage  108  may include two thicknesses to reduce an overall thickness of portable electronic device  100  while maintaining the spring force necessary to adequately cool the heat-generating component over which thermal stage  108  and heat pipe  106  are disposed, as described in further detail below with respect to  FIGS. 3-4 . 
     Third, wall  118  may include intake vents that are directed at a first angle toward one or more heat-generating components of portable electronic device  100  and exhaust vents directed at a second angle out of portable electronic device  100  to avoid a display of portable electronic device  100 . Wall  118  may also include one or more obstructed vents between the intake and exhaust vents, as well as mechanisms for reducing the temperature of hot spots in the enclosure of portable electronic device  100 . Wall  118  is described in further detail below with respect to  FIGS. 5-8 . 
     Finally, a set of gaskets  120 - 122  may provide thermal ducts between fans  102 - 104  and exhaust vents in wall  118  to prevent exhaust from recirculating inside portable electronic device  100  and reducing the effectiveness of heat dissipation from the heat-generating components. As discussed below with respect to  FIGS. 9-11 , gaskets  120 - 122  may include a rigid section that forms the duct, as well as a set of flexible sections that simplify assembly of heat pipe  106  on top of the rigid section and subsequently seal the duct around heat pipe  106 . 
       FIG. 2  shows a cross-sectional view of a system for facilitating heat transfer in a portable electronic device  200  (e.g., portable electronic device  100  of  FIG. 1 ). The system includes heat pipe  106  and thermal stage  108 , both of which are disposed over a heat-generating component  202  such as a CPU and/or GPU. 
     As shown in  FIG. 2 , thermal stage  108  may be disposed along a thermal interface in between heat pipe  106  and heat-generating component  202 . A thermal interface material (TIM)  214  may also be disposed within the thermal interface between heat-generating component  202  and thermal stage  108  to increase the thermal contact conductance between heat-generating component  202  and thermal stage  108 . 
     In one or more embodiments, the spring force of thermal stage  108  is used to increase thermal contact between heat-generating component  202  and heat pipe  106 . For example, thermal stage  108  may improve heat conduction between heat-generating component  202  and heat pipe  106  by reducing the thickness and, in turn, the thermal resistance of TIM  214 . As a result, thermal stage  108  may be made of a material with a high thermal conductivity and spring constant, such as copper titanium. 
     To provide thermal contact between heat-generating component  202  and heat pipe  106 , heat pipe  106  may be joined to thermal stage  108  using a solder  216 - 218 , and thermal stage  108  may be fastened to a surface  208  within portable electronic device  200  using a set of fasteners  204 - 206  (e.g., fasteners  110 - 116  of  FIG. 1 ). For example, fasteners  204 - 206  may include one or more screws that fasten a set of wings of thermal stage  108  to a printed circuit board (PCB) containing heat-generating component  202 . Fasteners  204 - 206  and thermal stage  108  may thus apply downward force onto heat-generating component  202  and increase the thermal coverage of heat-generating component  202  by heat pipe  106 . 
     Fasteners  204 - 206  may additionally form a thermal gap  220  between heat pipe  106  and an enclosure  222  of portable electronic device  200 . Continuing with the above example, screws used to provide fasteners  204 - 206  may have tall heads  210 - 212  that provide a 0.5 mm-0.8 mm thermal gap  220  and/or plenum through which air may flow to further cool heat-generating component  202  and/or other heat-generating components in portable electronic device  200 . Alternatively, other types of fasteners  204 - 206  may be used to provide thermal gap  220 , including: clips, barbed fasteners, bolts, clamps, pins, pegs, and/or clasps. 
     Thermal gap  220  may also prevent heat pipe  106  from thermally contacting enclosure  222  if portable electronic device  200  is dropped and/or impacts another object. For example, fasteners  204 - 206  may be placed around heat-generating component  202  if heat-generating component  202  is located relatively far from an attachment point of a metal enclosure  222  to ensure that trampolining in enclosure  222  does not cause heat pipe  106  to transfer heat to enclosure  222  and/or a surface contacting enclosure  222 . Fasteners  204 - 206  may further be attached to a surface (e.g., the center of a PCB) with lower stiffness so that the impact does not damage heat-generating component  202  and/or other nearby components. 
     However, the proximity of fasteners  204 - 206  to enclosure  222  may result in physical contact between fasteners  204 - 206  and enclosure  222 . For example, fasteners  204 - 206  may touch enclosure  222  if fasteners  204 - 206  are designed to be intimate with enclosure  222  and/or if fasteners  204 - 206  are brought in contact with enclosure  222  during impact between enclosure  222  and a hard object. 
     As a result, fasteners  204 - 206  may include an insulating material to prevent fasteners  204 - 206  from heating enclosure  222  in the event of physical contact between the fasteners  204 - 206  and enclosure  222 . For example, fasteners  204 - 206  may be made of plastic to reduce thermal conduction between fasteners  204 - 206  and enclosure  222 . Consequently, fasteners  204 - 206  may improve thermal contact between heat-generating component  202  and heat pipe  106 , provide thermal gap  220  as a channel for airflow and/or heat dissipation from heat-generating component  202  and/or heat pipe  106 , and facilitate safe operation of portable electronic device  200  by thermally insulating enclosure  222  from heat-generating component  202  and/or heat pipe  106 . 
       FIG. 3  shows a sectional view of a system  300  for facilitating heat transfer in a portable electronic device. As mentioned above, system  300  may include heat pipe  106  and thermal stage  108 , both of which are disposed over a heat-generating component  302  (e.g., a CPU). Heat pipe  106  may be soldered to thermal stage  108 , and a set of wings  304 - 306  of thermal stage  108  may be fastened to a surface within the portable electronic device to apply a spring force to heat-generating component  302 . For example, the fastening of wings  304 - 306  that are angled upward to a PCB containing heat-generating component  302  may apply a downward force onto heat-generating component  302  and increase the thermal contact conductance between heat-generating component  302  and heat pipe  106 . 
       FIG. 4  shows a side view of thermal stage  108 . Thermal stage  108  may include a number of regions  404 - 406  with different thicknesses. In particular, region  402  may be of a first thickness, and regions  404 - 406  may be of a second thickness that is greater than the first thickness. 
     The first and/or second thicknesses may be created in thermal stage  108  using a number of techniques. For example, a machining technique may be used to form a trough in a material (e.g., copper titanium) of uniform stock thickness. Similarly, a profile corresponding to the first thickness may also be formed in raw stock using a rolling technique. The first thickness may further be created by removing material from uniform stock using a skiving technique, continuous machining technique, and/or chemical-etching technique. A forging and/or coining technique may be used to press the first thickness into uniform stock, or a casting technique may be used to form the first and second thicknesses from a mold. 
     As mentioned above, the first thickness may accommodate a heat pipe (e.g., heat pipe  106  of  FIG. 1 ). For example, the first thickness may form a notch and/or groove within which the heat pipe may be placed to reduce an overall thickness of the portable electronic device containing thermal stage  108  and the heat pipe. On the other hand, the second thickness may increase a spring force between a heat-generating component and the heat pipe, allowing for better thermal transfer between the heat-generating component (e.g., a high-power CPU) and the heat pipe. For example, the second thickness may be used in the wings (e.g., wings  304 - 306  of  FIG. 3 ) of thermal stage  108  to increase the downward force applied by thermal stage  108  and/or a set of fasteners (e.g., fasteners  110 - 116  of  FIG. 1 ) onto the top of the heat-generating component. Consequently, the first and second thicknesses may facilitate both efficient use of space within the portable electronic device and increased cooling of the heat-generating component by the heat pipe. 
       FIG. 5  shows wall  118 . Wall  118  may be a rear wall of a portable electronic device, such as a laptop computer. The rear wall may be integrated into a top case of the laptop computer to reduce the number of seams and/or components in the laptop computer&#39;s enclosure. For example, instead of creating wall  118  as a separate part and subsequently joining wall  118  to the top case, wall  118  may be machined out of the top case. In turn, the reduced number of seams and/or components in the enclosure may mitigate electromagnetic interference caused by the enclosure and/or improve the rigidity and/or height tolerance of the enclosure. 
     As shown in  FIG. 5 , wall  118  includes an intake zone  502  and two exhaust zones  504 - 506 . Intake zone  502  includes a set of intake vents around the center of wall  118  that allow a set of fans (e.g., fans  102 - 104  of  FIG. 1 ) to draw cooler air from the exterior of the portable electronic device into the portable electronic device. The fans may then circulate the air inside a set of plenums and/or thermal gaps (e.g., thermal gap  220  of  FIG. 2 ) within the portable electronic device and expel the heated air out of the portable electronic device through a set of exhaust vents in exhaust zones  504 - 506  on either side of intake zone  502 . As discussed in further detail below with respect to  FIGS. 7-8 , the intake vents may be directed at a first angle toward one or more heat-generating components of the portable electronic device, and the exhaust vents may be directed at a second angle out of the portable electronic device. 
       FIG. 6  shows a rear view of a set of intake and exhaust zones  502 - 506  of a portable electronic device. As described above (and further below with respect to  FIG. 17 ), intake zone  502  may include a set of intake vents that are used by fans to draw in air from outside the portable electronic device, while each exhaust zone  504 - 506  may include a set of exhaust vents that are used by the fans to expel heated air out of the portable electronic device. 
     In addition, a set of obstructed vents  602 - 608  may separate intake zone  502  from exhaust zones  504 - 506 . Air flow from vents  602 - 608  may be blocked from the inside of the portable electronic device by a portion of a duct formed by a gasket in the portable electronic device, as described below with respect to  FIG. 10 . Such obstruction of substantially evenly spaced openings in intake and exhaust zones  502  and exhaust zones  504 - 506  may maintain the cosmetic continuity of the vents in intake and exhaust zones  502 - 506 , reduce electromagnetic interference from the enclosure of the portable electronic device, and facilitate heat dissipation in the portable electronic device by separating the intake and exhaust flows passing through intake and exhaust zones  502 - 506 , respectively. 
       FIG. 7  shows a cross-sectional view of a portable electronic device  700 . More specifically,  FIG. 7  shows a cross-sectional view of an exhaust vent  702  from an exhaust zone (e.g., exhaust zones  504 - 506  of  FIG. 5 ) in a wall (e.g., wall  118  of  FIG. 1 ) of portable electronic device  700 . Air from the interior of portable electronic device  700  may be moved by a fan (e.g., fans  102 - 104  of  FIG. 1 ) across heat pipe  106  and a heat sink  712 , where the air is heated and expelled as exhaust out of exhaust vent  702 . 
     In addition, as described further below with reference to  FIG. 20 , two flows  704 - 706  of exhaust out of vent  702  may be created by a clutch barrel  710  connecting a display of portable electronic device  700  (e.g., a laptop computer) to the bottom portion of portable electronic device  700 . Flow  704  may exit portable electronic device  700  along the bottom of clutch barrel  710 , while flow  706  may exit portable electronic device  700  over the top of clutch barrel  710 . To prevent exhaust from changing the white point of and/or accelerating degradation in the display, exhaust vent  702  may be directed at an angle out of portable electronic device  700  so that exhaust flows  704 - 706  avoid the display and/or do not create a large temperature gradient across the display. If the display is closed over the bottom portion of portable electronic device  700 , flow  706  may cease, and all exhaust may be expelled out of vent  702  through an air gap between the bottom of portable electronic device  700  and clutch barrel  710 . 
     Those skilled in the art will appreciate that exhaust flowing out of exhaust vent  702  may also heat material in the wall near exhaust vent  702  and create a hot spot in the enclosure of portable electronic device  700 . As a result, a T-cut  708  may be made in the material to reduce the thickness of the material and, in turn, the transfer of heat through the material. At the same time, the thickness of the material between exhaust vent  702  and one or more intake vents in portable electronic device  700  may be maintained to facilitate lateral conduction of heat from exhaust vent  702  to the intake vent(s), thus further reducing the temperature of the hot spot. Consequently, the relatively large size of exhaust vent  702 , T-cut  708 , and/or ridges at the bottom of exhaust vent  702  may provide a lightweight structure with thermally minimal spars, a reduced conduction path to both the top and bottom enclosures of portable electronic device  700 , and a lateral conduction path between the exhaust and intake zones in the wall. 
       FIG. 8  shows a cross-sectional view of a portable electronic device  800 . In particular,  FIG. 8  shows a cross-sectional view of an intake vent  802  from an intake zone (e.g., intake zone  502  of  FIG. 5 ) in a wall (e.g., wall  118  of  FIG. 1 ) of portable electronic device  800 . Intake vent  802  may allow cooler air from outside portable electronic device  800  to be drawn into portable electronic device  800  by a fan (e.g., fans  102 - 104  of  FIG. 1 ) and circulated within portable electronic device  800  before being expelled as exhaust out of one or more exhaust vents (e.g., exhaust vent  702  of  FIG. 7 ) in the wall. 
     Two flows  804 - 806  of air may pass through intake vent  802  while a display of portable electronic device  800  (e.g., a laptop computer) is open. Flow  804  may enter portable electronic device  800  along the bottom of a clutch barrel  810  connecting the display to the bottom of portable electronic device  800 , while flow  806  may enter portable electronic device  800  from the top of clutch barrel  810 . If the display is closed over the bottom of portable electronic device  800 , flow  806  may cease, and all air drawn in through intake vent  802  may flow  804  from an air gap between the bottom of portable electronic device  800  and clutch barrel  810 . 
     Moreover, intake vent  802  may be directed at an upward angle toward a heat-generating component  808  of portable electronic device  800  to facilitate heat dissipation from heat-generating component  808 . For example, intake vent  802  may channel air over the top of a PCB containing video memory to cool the video memory and/or other heat-generating components at the top of the PCB. As a result, air passing through intake vent  802  may dissipate heat from heat-generating component  808  better than air passing through an intake vent that is not angled upwards into the interior of portable electronic device  800 . 
       FIG. 9  shows a gasket  902  (e.g. gaskets  120 - 122  of  FIG. 1 ) in a portable electronic device. As mentioned above, gasket  902  may form a thermal duct between a fan  910  and a set of exhaust vents in wall  118  to prevent exhaust from recirculating inside the portable electronic device and reducing the effectiveness of heat dissipation from heat-generating components in the portable electronic device. 
     As shown in  FIG. 9 , gasket  902  may include three portions  904 - 908 . A rigid portion  904  may be disposed around a bottom of heat pipe  106  to form the duct between fan  910  and wall  118 . Two flexible portions  904 - 906  may then be bonded to rigid portion  904  so that gasket  902  is manufactured as a single component instead of multiple components that require multiple steps to assemble into gasket  902 . For example, flexible portions  904 - 906  may be made of a rubber that is bonded to a rigid portion  904  made of plastic using an overmolding technique. 
     Portion  906  may be a flap that is open during assembly of heat pipe  106  in the portable electronic device to allow heat pipe  106  to be placed over portions  904  and  908 . Portion  906  may then be closed over heat pipe  106  and portions  904  and  908  to seal the duct around heat pipe  106  after the assembly. Portions  904 - 906  may further seal the duct around fan  910 , a bottom enclosure (not shown) of the portable electronic device, a top enclosure  912  of the portable electronic device, and/or exhaust vents in wall  118 . For example, portion  906  may fold over portions  904  and  908  to seal along the top of fan  910 , the top and/or sides of heat pipe  106 , and/or the bottom enclosure. On the other hand, portion  908  may be bonded to one or more edges of portion  904  and seal along the bottom of fan  910 , the bottom and/or sides of heat pipe  106 , top enclosure  912 , and/or wall  118 . Gasket  902  may also include an additional flexible portion  914  that seals the duct along wall  118 . Alternatively, portion  914  may be provided by a separate component (e.g., a gasket) disposed between gasket  902  and wall  118 . 
       FIG. 10  shows flexible portion  906  of a gasket (e.g., gasket  902  of  FIG. 9 ). As mentioned above, portion  906  includes a flap that is open during assembly of heat pipe  106  in the portable electronic device. For example, the portable electronic device may be assembled by placing the gasket into the top enclosure of the portable electronic device with portion  906  open over wall  118 . After the gasket is placed into the top enclosure of the portable electronic device, a part of rigid portion  904  may obstruct one or more vents in wall  118  to separate the intake and exhaust zones of wall  118 . Next, fan  910  may be placed next to the gasket, and heat pipe  106  may be placed on top of rigid portion  904  and/or a second flexible portion (e.g., portion  908  of  FIG. 9 ) of the gasket. 
       FIG. 11  shows flexible portion  906  of a gasket (e.g., gasket  902  of  FIG. 9 ). As shown in  FIG. 11 , portion  906  may be closed over heat pipe  106 , rigid portion  904 , and the second flexible portion after heat pipe  106  is assembled in the portable electronic device. The bottom enclosure of the portable electronic device may then be placed over the gasket to create a compression seal around heat pipe  106 , fan  910 , one or more exhaust vents of wall  118 , and/or the top enclosure of the portable electronic device. In addition, the insulating materials used in the gasket may restrict heat transfer between the exhaust and the enclosure of the portable electronic device, thus facilitating safe operation of the portable electronic device. 
       FIG. 12  shows a flow chart illustrating a method  1200  of facilitating heat transfer in a portable electronic device. During this method, a first thickness to accommodate a heat pipe in the portable electronic device and a second thickness that is greater than the first thickness to increase a spring force between the heat-generating component and the heat pipe are provided in a thermal stage (operation  1202 ). The thermal stage may be made of copper titanium and/or another material with a high thermal conductivity and/or spring constant. The first and/or second thicknesses may be created using a machining technique, a rolling technique, a skiving technique, a forging technique, a coining technique, a chemical etching technique, and/or a casting technique. 
     Next, a TIM is disposed between the heat-generating component and the thermal stage (operation  1204 ). For example, the TIM may be applied to a surface of the heat-generating component and/or the thermal stage. The thermal stage is then disposed along a thermal interface between the heat-generating component and the heat pipe (operation  1206 ), and the heat pipe is joined to the thermal stage using a solder (operation  1208 ). For example, the thermal stage may be placed over the heat-generating component, and the heat pipe may be placed over the thermal stage and soldered to the thermal stage. 
     The thermal stage is also fastened to a surface within the portable electronic device using a set of fasteners (operation  1210 ), and the set of fasteners is used to form a thermal gap between the heat pipe and the enclosure of the portable electronic device (operation  1212 ). For example, the fasteners may include screws with tall heads that form a plenum between the heat pipe and enclosure through which air may flow to further dissipate heat from the heat-generating component. The screws may also separate the heat pipe from the enclosure, thus preventing the heat pipe from transmitting large amounts of heat through the enclosure. Similarly, the heads of the screws may include an insulating material such as plastic to prevent the heat-generating component from thermally contacting the enclosure if the enclosure touches the screws&#39; heads (e.g., as a result of impact between the portable electronic device and a hard surface and/or by design). 
       FIG. 13  shows a flow chart illustrating a method  1300  of facilitating heat transfer in a portable electronic device. During this method, a wall of the portable electronic device that includes an intake zone containing a set of intake vents directed at a first angle toward one or more heat-generating components of the portable electronic device and an exhaust zone containing a set of exhaust vents directed at a second angle out of the portable electronic device is provided (operation  1302 ). For example, the wall may be a rear wall that is integrated into a top case of a laptop computer. The first angle may facilitate the cooling of components at the top of a PCB in the laptop computer, while the second angle may direct exhaust out of the laptop computer so that the exhaust avoids the display of the laptop computer. 
     Next, one or more vents between the intake zone and exhaust zone are obstructed (operation  1304 ). The vents may be obstructed by a portion of a duct between a fan and the exhaust zone and/or another component in the portable electronic device. The obstructed vents may maintain the cosmetic continuity of the portable electronic device while separating the intake and exhaust flows passing through the intake and exhaust zones. 
     Material adjacent to the exhaust vent may also be removed to reduce a temperature of a hot spot in the material during the transfer of exhaust out of the portable electronic device (operation  1306 ). For example, the material may be removed using a T-cut to reduce the amount of heat conducted through the material to the outside of the portable electronic device&#39;s enclosure. The temperature of the hotspot may further be reduced by maintaining the thickness of the material between the exhaust vent and one or more intake vents (operation  1308 ) in the portable electronic device. For example, the thickness of material separating the exhaust vent from an intake vent to the side of the exhaust vent may be maintained to facilitate lateral conduction of heat from the exhaust vent to the intake vent. 
       FIG. 14  shows a flow chart illustrating a method  1400  of assembling a portable electronic device. During this method, a gasket containing a rigid portion forming a duct between a fan and exhaust vent of the portable electronic device, with a first flexible portion containing a flap, and a second flexible portion bonded to one or more edges of the rigid portion, is placed within an enclosure of the portable electronic device (operation  1402 ). For example, the gasket may be placed inside a top enclosure of the portable electronic device so that one end of the gasket is flush with a wall (e.g., wall  118  of  FIG. 1 ) containing the exhaust vent, and a fan may be installed in the portable electronic device so that the other end of the gasket is flush with the fan. The rigid portion may be made of plastic, while the first and second flexible portions may be made of a rubber that is bonded to the rigid portion using an overmolding technique. 
     Next, a heat pipe is disposed over the rigid portion and second flexible portion while the flap is open (operation  1404 ). For example, the heat pipe may be assembled in the portable electronic device so that the heat pipe rests on top of the rigid portion and second flexible portion while the flap is open over the wall. 
     Moreover, the flap is closed over the heat pipe, the rigid portion, and the second flexible portion to seal the duct around the heat pipe (operation  1406 ). The first and second flexible portions may also seal the duct around the fan, the bottom enclosure of the portable electronic device, the top enclosure of the portable electronic device, and/or the exhaust vent. The gasket may thus prevent recirculation of exhaust within the portable electronic device, simplify the assembly of the heat pipe and/or portable electronic device, and/or insulate the enclosure of the portable electronic device from the heated exhaust. 
     We now describe additional embodiments.  FIG. 15  presents a block diagram illustrating a side view of a portable electronic device  1500 , such as portable electronic device  700  ( FIG. 7 ). This portable electronic device includes an external housing with a top case  1510  and a bottom case  1512  that each has inner surfaces  1514  that define an internal cavity  1516 . Internal cavity  1516  includes at least an integrated circuit  1518  that generates heat during operation of portable electronic device  1500 . Moreover, one or more heat exchangers  1520  (such as convective-cooling fins) in internal cavity  1516 , which are thermally coupled to integrated circuit  1518 , may passively transfer the thermal power away from integrated circuit  1518 . Furthermore, one or more forced-fluid drivers  1522  (such as one or more fans) in internal cavity  1516  drive one or more fluid flows  1524  (such as a fluid flow in a gas, for example, air) through heat exchanger(s)  1520  and out of portable electronic device  1500  via one or more fluid-flow ports  1526  in the external housing so that, during operation of portable electronic device  1500 , the thermal power is transported away from heat exchanger(s)  1520 . Note that there are vertical gaps  1528  between heat exchanger(s)  1520  and top case  1510  and bottom case  1512  so that, during operation of portable electronic device  1500 , additional fluid flows  1530  (such as an additional fluid flow in a gas, for example, air) through vertical gaps  1528  are located above and below fluid flow(s)  1524 . 
     After passing through heat exchanger(s)  1520  during operation of portable electronic device  1500 , a temperature of fluid flow(s)  1524  may be higher than those of additional fluid flows  1530 . Furthermore, fluid-flow port(s)  1526  may have a length  1532 , and mixing of additional fluid flows  1530  and fluid flow(s)  1524  may be at most partial over length  1532 . 
     As shown in  FIG. 16 , which presents a block diagram illustrating a top view of portable electronic device  1500 , in some embodiments interval cavity  1516  includes an optional heat pipe  1534  thermally coupled to integrated circuit  1518  at an evaporator region  1536  of optional heat pipe  1534 . During operation of portable electronic device  1500 , optional heat pipe  1534  may transport the thermal power from evaporator region  1536  to one or more condenser regions  1538  of optional heat pipe  1534 , and heat exchanger(s)  1520  may be thermally coupled to optional heat pipe  1534  at condenser region(s)  1538 . 
     Referring back to  FIG. 15 , additionally internal cavity  1516  may include one or more optional ducts, such as optional duct  1540 , located above heat exchanger(s)  1520  and mechanically coupled to top case  1510 , which guide the upper additional fluid flows, such as additional fluid flow  1530 - 1  shown in  FIG. 15 , over a top of heat exchanger(s)  1520 . By guiding the upper additional fluid flows in this way, and in particular by keeping the upper additional fluid flows away from top case  1510 , optional duct  1540  may ensure that there is not excessive heating of top case  1510 , which may be noticed by a user of portable electronic device  1500 . 
     In an exemplary embodiment, vertical gap  1528 - 1  has a height  1544  of 2.5 mm, heat exchanger(s)  1520  have height(s)  1546  of 4-5 mm, and vertical gap  1528 - 2  has a height  1548  of 1 mm. Moreover, a space  1550  between heat exchanger(s)  1520  and fluid-flow port(s)  1526  may be 2 mm, length  1532  may be 4 mm, and (as shown below in  FIG. 17 ) there may be a space  1720  ( FIG. 17 ) of 4-5 mm between fluid-flow port(s)  1526  and housing  1716  ( FIG. 17 ). Furthermore, optional heat pipe  1534  may have a thickness  1552  of less than or equal to 1.3 mm. 
     By including vertical gaps  1528 , portable electronic device  1500  may output heat in higher temperature fluid flow(s)  1524  sandwiched between lower temperature, additional fluid flows  1530 . As described below with reference to  FIGS. 17-20 , this may allow a thermal impact of higher temperature fluid flow(s)  1524  on a display (such as a liquid-crystal display) in the portable electronic device to be reduced or eliminated. Therefore, by intentionally reducing the thermal efficiency of heat exchanger(s)  1520  by reducing their height along bypass flows (i.e., additional fluid flows  1530 ), portable electronic device  1500  may reduce or eliminate color changes and other visual artifacts that can degrade the quality of a displayed image on the display. 
     As shown in  FIG. 16 , instead of or in addition to vertical gaps  1528  around heat exchanger(s)  1520 , in some embodiments there may be one or more optional horizontal gaps  1610  between heat exchanger(s)  1520  and wall(s)  1612  of internal cavity  1516  in a horizontal plane  1542  ( FIG. 15 ) of heat exchanger(s)  1520  so that one or more additional fluid flows  1614  flow through optional gap(s)  1610 . Once again, fluid flow(s)  1524  may have a higher temperature than that of additional fluid flow(s)  1614 , and mixing of additional fluid flow(s)  1614  and fluid flow(s)  1524  may be at most partial over length  1532  ( FIG. 15 ) of fluid-flow port(s)  1526 . 
     Furthermore, portable electronic device  1500  may include: one or more components  1616  adjacent to wall(s)  1612  of internal cavity  1516 , where optional gap(s)  1610  are located; and one or more optional duct(s)  1618 , located in optional gap(s)  1610 , which guide additional fluid flow(s)  1614  over component(s)  1616 . For example, component(s)  1616  may be temperature sensitive, and optional duct(s)  1618  may ensure that additional fluid flow(s)  1614  pass over component(s)  1616  without heating them. Thus, once again, the efficiency of heat exchanger(s)  1520  may be intentionally reduced using bypass flows to reduce or eliminate heating of temperature-sensitive components in the portable electronic device. 
       FIG. 17  presents a block diagram illustrating a top view of a portable electronic device  1700 , such as portable electronic device  700  ( FIG. 7 ). This portable electronic device includes a rotatable display  1710  that is mechanically coupled to external housing  1712  by a hinge  1714 . As shown in  FIG. 20 , which presents a block diagram illustrating a side view of a portable electronic device  1700 , rotatable display  1710  ( FIG. 17 ) and housing  1716  have a configurable angular position  2010  relative to a plane  2012  of top case  1510  in external housing  1712  ( FIG. 17 ). 
     Referring back to  FIG. 17 , portable electronic device  1700  includes a housing  1716  (such as a clutch barrel) that at least partially encloses hinge  1714  along an axis of rotation  1718  of rotatable display  1710 . As discussed previously, during operation of portable electronic device  1700 , fluid-flow port(s)  1526  in external housing  1712  direct fluid flows  1524  and  1530  ( FIG. 15 ) out of internal cavity  1516  ( FIG. 15 ). These fluid flows include central fluid flow(s)  1524  ( FIG. 15 ) sandwiched between additional fluid flows  1530  ( FIG. 15 ), where central fluid flow(s)  1524  ( FIG. 15 ) have a higher temperature than those of additional fluid flows  1530  ( FIG. 15 ). Housing  1716  may direct central fluid flow(s)  1524  ( FIG. 15 ) away from rotatable display  1710  over a range of angular positions of rotatable display  1710 . For example, the range of angular positions may include approximately 0° (which is described further below with reference to  FIGS. 18 and 19 ) and approximately between 90° to 110° or 135° (which is described further below with reference to  FIG. 20 , and was also described previously with reference to  FIGS. 7 and 8 ). 
     As shown in  FIG. 18 , which presents a block diagram illustrating a side view of a portable electronic device  1700 , when angular position  2010  ( FIG. 20 ) is approximately 0° (i.e., in a closed position), housing  1716  may direct central fluid flow(s)  1524 , such as fluid flow  1524 - 1 , out of portable electronic device  1700 . In particular, housing  1716  may provide a ramp feature for this purpose. In the process, housing  1716  may ensure that the cooling of portable electronic device  1700  is the same when rotatable display  1710  is in an open or closed position, and therefore that the performance of portable electronic device  1700  is the same independent of angular position  2010  ( FIG. 20 ). This configuration is further illustrated in  FIG. 19 . 
     Furthermore, as shown in  FIG. 20 , when angular position  2010  is approximately between 90° and 110° (i.e., in an open position), housing  1716  may direct central fluid flow(s)  1524 , such as fluid flow  1524 - 1 , into housing  1716 , and may direct additional fluid flow  1530 - 1  to rotatable display  1710  ( FIG. 17 ) and additional fluid flow  1530 - 2  out of portable electronic device  1700 . (Note that when angular position  2010  is less than 90° it may be difficult for a user of portable electronic device  1700  to view information on rotatable display  1710 ) Thus, additional fluid flows  1530  may provide an air curtain around central fluid flow(s)  1524  which is directed toward rotatable display  1710  ( FIG. 17 ) to reduce or eliminate heating of rotatable display  1710  ( FIG. 17 ). 
     Referring back to  FIG. 17 , in some embodiments, during operation of portable electronic device  1700 , housing  1716  may reduce a flow impedance of fluid flow  1620  ( FIG. 16 ) in fluid-flow port  1622  ( FIG. 16 ) into portable electronic device  1700 . For example, there may be an unimpeded path into internal cavity  1516  ( FIG. 15 ), as illustrated by the dotted line in  FIGS. 18 and 20 , which may facilitate fluid flow  1620  ( FIG. 16 ). Note that fluid flow  1620  ( FIG. 16 ) may be separated by regions  1624  ( FIG. 16 ) without fluid flows into or out of portable electronic device  1700 . Additionally, during operation of portable electronic device  1700 , housing  1716  may direct a portion of fluid flow  1620  ( FIG. 16 ) over an integrated circuit, such as integrated circuit  1518  ( FIG. 15 ). 
     We now describe embodiments of methods that can be performed using the preceding embodiments.  FIG. 21  presents a flowchart illustrating a method  2100  for cooling a cavity (such as internal cavity  1516  in  FIG. 15 ) in portable electronic device  1500  ( FIGS. 15 and 16 ). During operation of the portable electronic device, the forced-fluid driver generates the fluid flow through the heat exchanger in the cavity so that thermal power associated with operation of the integrated circuit in the cavity is transported out of the cavity (operation  2110 ). Moreover, the forced-fluid driver generates additional fluid flows through the vertical gaps between the heat exchanger and the walls of the cavity so that the additional fluid flows through the vertical gaps are located above and below the fluid flow (operation  2112 ). 
       FIG. 22  presents a flowchart illustrating a method  2200  for cooling a cavity in the portable electronic device  1500  ( FIGS. 15 and 16 ). During operation of the portable electronic device, the forced-fluid driver generates the fluid flow through the heat exchanger in the cavity so that thermal power associated with operation of the integrated circuit in the cavity is transported out of the cavity (operation  2110 ). Moreover, the forced-fluid driver generates an additional fluid flow through the gap between the heat exchanger and the wall of the cavity in a horizontal plane of the heat exchanger so that an additional fluid flow flows through the gap (operation  2212 ). 
       FIG. 23  presents a flowchart illustrating a method  2300  for cooling a cavity in the portable electronic device  1700  ( FIGS. 17-20 ). During operation of the portable electronic device, the forced-fluid driver generates fluid flows through the fluid-flow port so that thermal power associated with operation of at least an integrated circuit in the cavity is transported out of the cavity (operation  2310 ), where the fluid flows include the central fluid flow sandwiched between two additional fluid flows, and the central fluid flow has the higher temperature than those of the additional fluid flows. Moreover, the housing directs the central fluid flow away from the rotatable display in the portable electronic device that at least partially encloses the hinge that facilitates the configurable angular position of the rotatable display relative to the plane of the top case in the portable electronic device (operation  2312 ). Note that the central fluid flow is directed away from the rotatable display over the range of angular positions of the rotatable display. 
     In some embodiments, the housing optionally reduces the flow impedance of the other fluid flow in the other fluid-flow port into the portable electronic device. Additionally, the housing may optionally direct the portion of the other fluid flow over at least the integrated circuit. 
     In some embodiments of methods  1200  ( FIG. 12 ),  1300  ( FIG. 13 ),  1400  ( FIG. 14 ),  2100  ( FIG. 21 ),  2200  ( FIG. 22 ) or  2300  there may be additional or fewer operations. Moreover, the order of the operations may be changed, and/or two or more operations may be combined into a single operation. 
     The above-described heat transfer mechanisms can generally be used in any type of electronic device. For example,  FIG. 24  illustrates a portable electronic device  2400  which includes a processor  2402 , a memory  2404  and a display  2408 , which are all powered by a battery  2406 . This portable electronic device may include: one or more program modules or sets of instructions stored in an optional memory subsystem (not shown). These sets of instructions may be executed by an optional processing subsystem (such as one or more processors) on a motherboard (not shown). Note that the one or more computer programs may constitute a computer-program mechanism. Moreover, instructions in the various modules in the optional memory subsystem may be implemented in: a high-level procedural language, an object-oriented programming language, and/or in an assembly or machine language. Furthermore, the programming language may be compiled or interpreted, e.g., configurable or configured, to be executed by the optional processing subsystem. 
     In some embodiments, functionality in these circuits, components and devices may be implemented in one or more: application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), and/or one or more digital signal processors (DSPs). Moreover, the circuits and components may be implemented using any combination of analog and/or digital circuitry, including: bipolar, PMOS and/or NMOS gates or transistors. Furthermore, signals in these embodiments may include digital signals that have approximately discrete values and/or analog signals that have continuous values. Additionally, components and circuits may be single-ended or differential, and power supplies may be unipolar or bipolar. 
     Portable electronic device  2400  may include one of a variety of devices that can include memory, including: a laptop computer, a media player (such as an MP3 player), an appliance, a subnotebook/netbook, a tablet computer, a smartphone, a cellular telephone, a network appliance, a personal digital assistant (PDA), a toy, a controller, a digital signal processor, a game console, a device controller, a computational engine within an appliance, a consumer-electronic device, a portable computing device, a digital camera, a personal organizer, and/or another electronic device, such as another type of battery-powered electronic device. 
     In order to cool heat-generating components in portable electronic device  2400 , portable electronic device  2400  may include a heat pipe that conducts heat away from the heat-generating components and/or one or more fans that expel the heat out of portable electronic device  2400 . 
     Portable electronic device  2400  may also include a thermal stage disposed along a thermal interface between a heat-generating component and the heat pipe. The thermal stage may include a first thickness to accommodate the heat pipe and a second thickness that is greater than the first thickness to increase the spring force between the heat-generating component and the heat pipe. The thermal stage may also be fastened to a surface within portable electronic device  2400  by a set of fasteners that form a thermal gap between the heat pipe and the enclosure of portable electronic device  2400 . 
     Moreover, in order to further facilitate cooling of the heat-generating components, a wall of portable electronic device  2400  may include an intake zone containing a set of intake vents directed at a first angle toward one or more of the heat-generating components. The wall may also include an exhaust zone containing a set of exhaust vents directed at a second angle out of the electronic device (e.g., to avoid a display of the electronic device). One or more vents may be obstructed between the intake and exhaust zones to separate the intake and exhaust zones. In addition, the temperature of a hot spot near an exhaust vent may be reduced by removing material adjacent to the exhaust vent and/or maintaining a thickness of the material between the exhaust vent and one or more intake vents. 
     Furthermore, a gasket may prevent the recirculation of exhaust inside the electronic device. The gasket may include a rigid portion that forms a duct between a fan and an exhaust vent. The gasket may also include a first flexible portion bonded to the rigid portion, as well as a second flexible portion bonded to one or more edges of the rigid portion. The first flexible portion may be a flap that is open during assembly of the heat pipe in the electronic device and closed over the heat pipe and the rigid portion to seal the duct around the heat pipe after the assembly. The first and second flexible portions may further seal the duct around the fan, the bottom enclosure of the electronic device, the top enclosure of the electronic device, and/or the exhaust vent. 
     While a portable electronic device was used as an illustration in the preceding discussion, in other embodiments the heat-transfer technique is included in an electronic device, such as a server, a desktop computer, a mainframe computer and/or a blade computer. 
     Additionally, one or more of the components may not be present in the  FIGS. 1-11 and 15-20 . In some embodiments, the preceding embodiments include one or more additional components that are not shown in  FIGS. 1-11 and 15-20 . Also, although separate components are shown in  FIGS. 1-11 and 15-20 , in some embodiments some or all of a given component can be integrated into one or more of the other components and/or positions of components can be changed. 
     In the preceding description, we refer to ‘some embodiments.’ Note that ‘some embodiments’ describes a subset of all of the possible embodiments, but does not always specify the same subset of embodiments. 
     The foregoing description is intended to enable any person skilled in the art to make and use the disclosure, and is provided in the context of a particular application and its requirements. Moreover, the foregoing descriptions of embodiments of the present disclosure have been presented for purposes of illustration and description only. They are not intended to be exhaustive or to limit the present disclosure to the forms disclosed. Accordingly, many modifications and variations will be apparent to practitioners skilled in the art, and the general principles defined herein may be applied to other embodiments and applications without departing from the spirit and scope of the present disclosure. Additionally, the discussion of the preceding embodiments is not intended to limit the present disclosure. Thus, the present disclosure is not intended to be limited to the embodiments shown, but is to be accorded the widest scope consistent with the principles and features disclosed herein.

Metadata:
Filing Date: 20190715
Publication Date: 20210316
Grant Date: 20210316
Priority Date: 20120608
Inventors: DEGNER, BRETT W.
ANDRE, BARTLEY K.
BATAILLOU, JEREMY D.
NIGEN, JAY S.
LIGTENBERG, CHRISTIAAN A.
HOPKINSON, Ron A.
SCHWALBACH, CHARLES A.
CASEBOLT, MATTHEW P.
RUNDLE, NICHOLAS A.
LIANG, FRANK F.
Assignee: APPLE INC
CPC Classifications: [{"code": "G06F1/203", "inventive": true, "first": true, "tree": "[]"}, {"code": "Y10T29/49002", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K7/2039", "inventive": true, "first": false, "tree": "[]"}, {"code": "Y10T29/49002", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F1/203", "inventive": true, "first": true, "tree": "[]"}, {"code": "H05K7/20145", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K7/2039", "inventive": true, "first": false, "tree": "[]"}, {"code": "Y10T29/49002", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F1/203", "inventive": true, "first": true, "tree": "[]"}, {"code": "H05K7/20145", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 49714367