Abstract:
In general, the disclosure is directed to sealed enclosures and devices that include enclosures for protecting enclosed heat sensitive components from the heat generated by enclosed heat producing components. Heat producing components within the enclosure may be placed to achieve uniform distribution of heat produced by the heat producing components, to optimize the dissipation of heat from the heat producing components to the enclosure, and to minimize the heat experienced by the heat sensitive components. The exterior of the enclosure may be designed to increase thermal dissipation and to protect against thermal radiation.

Description:
TECHNICAL FIELD 
       [0001]    The disclosure relates to a mechanical enclosure, and more specifically relates to a substantially sealed enclosure that encloses electromechanical components. 
       BACKGROUND 
       [0002]    Sensitive electronic components may be protected from harsh operating environments by being enclosed in a substantially air-proof and dust-proof enclosure. For example, in an automotive application, the sensitive electronic components may be subject to harsh vibrations, high temperatures, and environmental contaminants such as dirt, oil, fluids, and the like. While the enclosure keeps contaminants away from the enclosed sensitive electronic components by being substantially sealed, the sealed design of the enclosures may also trap in the heat produced by the enclosed electronic components such as microprocessors and high speed memory. 
       SUMMARY 
       [0003]    In general, this disclosure is directed towards protecting heat sensitive components in a substantially sealed enclosure from the heat generated by heat producing components that are also within the enclosure. Because the enclosure is substantially sealed, convectional heat dissipation techniques such as fan cooling cannot efficiently dissipate heat generated by the heat producing components. Direct heat extraction from a printed circuit board to the enclosure without thermal pads is also not used because reverse current generated during welding of the enclosure can damage the heat sensitive components through ground plane shorting. In addition, heat pipes are also not used because enclosures that include heat pipes are unlikely to pass stringent vibration and drop tests. Instead, heat producing components may be placed within the enclosure to optimally distribute the heat produced by the heat producing components, to optimize the transfer of heat from the heat producing components to the enclosure, and to minimize the heat experienced by the heat sensitive components. Furthermore, the exterior of the enclosure may be designed to increase thermal dissipation and to protect against thermal radiation. 
         [0004]    In one aspect, the disclosure is directed to a device. The device may include an anodized and substantially sealed enclosure, the enclosure including a powder coated exterior, the exterior of the enclosure including a plurality of fins. The device may further include a first printed circuit board disposed within an interior and substantially parallel to a first surface in the interior of the enclosure. The device may further include one or more first heat producing components operably coupled to the first printed circuit board. The device may further include one or more first gap filler thermal pads disposed between the one or more first heat producing components and one or more first portions of the first surface in the interior of the enclosure. The device may further include one or more heat sensitive components disposed within the interior of the enclosure. The one or more first heat producing components in the device may be disposed on a first surface of the first printed circuit board facing away from the one or more heat sensitive components and facing towards the first surface in the interior of the enclosure. 
         [0005]    In another aspect, the disclosure is directed to an enclosure. The enclosure may include an exterior that is anodized and includes a powder coating. The enclosure may further include an interior that is anodized. The enclosure may further include a plurality of fins extending out from the exterior. The enclosure may further include a plurality of heat sensitive components disposed within the enclosure. The enclosure may further include a plurality of first heat producing components disposed within the enclosure, wherein the plurality of first heat producing components are disposed closer to a first portion of the interior than the heat sensitive component. The enclosure may further include a plurality of second heat producing components within the enclosure, wherein the plurality of second heat producing components are disposed closer to a second portion of the interior than the heat sensitive components, wherein the second portion of the interior is substantially parallel to the first portion of the interior. The enclosure may be substantially sealed. 
         [0006]    The details of one or more aspects of the disclosure are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the disclosure will be apparent from the description and drawings, and from the claims. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0007]      FIG. 1A  is perspective view illustrating the exterior of an example enclosure according to aspects of the disclosure. 
           [0008]      FIG. 1B  is a plan view illustrating the exterior of an example enclosure according to some aspects of the disclosure. 
           [0009]      FIGS. 1C-1E  are elevation views illustrating the exterior of an example enclosure according to some aspects of the disclosure. 
           [0010]      FIG. 2A  is an exploded perspective view illustrating an example enclosure according to aspects of the disclosure. 
           [0011]      FIG. 2B  is a cross-section view illustrating an example enclosure according to aspects of the disclosure. 
           [0012]      FIGS. 3A-3B  are plan views illustrating an example processor board according to aspects of the disclosure. 
           [0013]      FIG. 3C  is a cross-section view illustrating an example processor board according to aspects of the disclosure. 
           [0014]      FIGS. 4A-4B  are plan views illustrating an example power supply board according to aspects of the disclosure. 
           [0015]      FIG. 4C  is a cross-section view illustrating an example power supply board according to aspects of the disclosure. 
           [0016]      FIGS. 5A-5B  are plan views illustrating plan views of an example sensor board according to aspects of the disclosure. 
       
    
    
     DETAILED DESCRIPTION 
       [0017]      FIG. 1A  is perspective view illustrating the exterior of an example enclosure according to aspects of the disclosure.  FIG. 1B  is a plan view illustrating the exterior of an example enclosure according to some aspects of the disclosure.  FIGS. 1C-1E  are elevation views illustrating the exterior of an example enclosure according to some aspects of the disclosure. As shown in  FIGS. 1A-1E , enclosure  100  may be a substantially rectangular shaped mechanical enclosure that houses electronic components. Enclosure  100  may be substantially sealed, such as by being substantially dust-proof, air-proof, and waterproof and/or by meeting the requirement of IP69K or IP67K ratings as defined by the International Electrotechnical Commission (IEC) 60529 standard, the Deutsches Institut für Normung (DIN) 40050-9 standard, and/or the National Electrical Manufacturers Association (NEMA) standard. These standards may rate the degrees of protection provided against the intrusion of solid objects, dust, accidental contact, and water in mechanical and electrical enclosures. In other examples, techniques of this disclosure may also be applicable to non-seal-proof and/or non-IP67K and non-IP69K enclosure applications. In some examples, enclosure  100  may house one or more sensors and may be used in automotive applications in environments with temperatures of 85° C. and higher, and may also be required to meet specified electrostatic discharge, electromagnetic interference, and electromagnetic compatibility criteria. 
         [0018]    The exterior of enclosure  100  may act as a heat sink by incorporating thermal dissipation features that aids the dissipation of heat produced by the heat producing components such as processors and high speed memory enclosed by enclosure  100 , so that heat sensitive components such as micro-electromechanical systems (MEMS) sensors or other heat sensitive electromechanical components in enclosure  100  remain in an optimal operating temperature range. In some examples, enclosure  100  is a metal enclosure, such as an aluminum alloy enclosure, that is anodized on both its interior and exterior surfaces. In some examples, enclosure  100  is completely anodized. Anodizing enclosure  100  increases thermal dissipation through enclosure  100  and increases thermal conductivity of heat from enclosure  100  to the operating environment. The exterior of enclosure  100  may also be powder coated with a white powder coating over the anodized aluminum. In such examples, the power coating protects enclosure  100  against electrostatic discharge, while the white color of the powder coating protects enclosure  100  against thermal radiation from heat sources in the operating environment of enclosure  100 . The weight of the powder coating may be negligible compared to the weight of enclosure  100 . 
         [0019]    Enclosure  100  may include fins  102 . Fins  102  may increase the surface area exterior to enclosure  100 , thereby decreasing thermal resistance of enclosure  100  and increasing thermal dissipation by enclosure  100  due to the additional surface area provided by fins  102 . As can be seen, enclosure  100  may be a substantially rectangular enclosure, and fins  102  may extend out of one or more exterior surfaces of enclosure  100 , such as sides  108 ,  110 , and  112  of enclosure  100 . Fins  102  may be made of metal, such as aluminum alloy, may be parabolic in shape, and may each have an adiabatic tip (e.g. a completely insulated tip). Like enclosure  100 , fins  102  may also be anodized and powder coated with a white color. The weight of fins  102  may be negligible compared to the weight of enclosure  100 . In some examples, enclosure  100  includes twenty-two fins  102  that extend out of three exterior surfaces  108 ,  110 , and  112  of enclosure  100 , but do not extend out of top surface  104  and bottom surface  106  or surface  114  of enclosure  100 , and are substantially parallel to each other. Each of the twenty-two fins  102 , in some examples, may be 49 millimeters tall, 3.75 millimeters wide, and may extend 7 millimeters from sides  108   110 , and  112 , and may achieve an overall fin efficiency of about 41.3% and a total heat dissipation through the twenty-two fins  102  of about 4.44 watts. Connector  116  may extend out of surface  114  of enclosure  100 . 
         [0020]      FIG. 2A  is an exploded perspective view illustrating an example enclosure according to aspects of the disclosure.  FIG. 2B  is a cross-section view illustrating an example enclosure according to aspects of the disclosure. As shown in  FIGS. 2A and 2B , enclosure  100  may include bottom surface  106  and top surface  104  opposite to bottom surface  106 , and the interior surface of top surface  104  may be opposite and substantially parallel to the interior surface of bottom surface  106 . Similar to the exterior surface of enclosure  100 , the interior surface of enclosure  100  may also be anodized. Enclosure  100  may include heat producing components  208  and heat sensitive components  210 , so that heat producing components may be disposed within enclosure  100  closer to the interior surface of either top surface  104  or bottom surface  106  than heat sensitive components  210 . 
         [0021]    Enclosure  100  may enclose power supply board  202 , processor board  204 , and sensor board  206 . Heat producing components  208  are operably coupled to power supply board  202  and processor board  204 , while heat-sensitive components  210  are operably coupled to sensor board  206 . Power supply board  202 , processor board  204 , and sensor board  206  may be printed circuit boards and may be disposed substantially parallel to top surface  104  and bottom surface  106  of enclosure  100 . 
         [0022]    Heat producing components  208  operably coupled to power supply board  202  may include a computer automotive network transceiver, a low dropout regulator, diodes, transistors, a DC-DC converter, and the like. Power supply board  202  may also include a connector  116 . Heat producing components  208  operably coupled to processor board  204  may include processors, memory, a power management integrated circuit, a low drop out regulator, and the like. Heat sensitive components  210  operably coupled to sensor board  206  may include one or more gyroscopes, an accelerometer, a magnetometer, and the like. Sensor board  206  may also include dampers  212 , such as elastomeric dampers, that are coupled to enclosure  100  to dampen the vibration felt by heat sensitive components  210  on sensor board  206  and to further isolate those components  210  from heat generating components  208 . 
         [0023]    As can be seen, sensor board  206  may be disposed between power supply board  202  and processor board  204 . Power supply board  202  is disposed closer to the interior surface of bottom surface  106  within the interior of enclosure  100  than sensor board  206 , and processor board  204  is disposed closer to the interior surface of top surface  104  in the interior of enclosure  100  than sensor board  206 . In some example, power supply board  202  may be closer to the interior surface of bottom surface  106  than power supply board  202  is to sensor board  206 , and processor board  204  may be closer to the interior surface of top surface  104  than processor board  204  is to sensor board  206 . 
         [0024]    Heat producing components  208  operably coupled to power supply board  202  and processor board  204  may be disposed on the respective surfaces of power supply board  202  and processor board  202  facing away from sensor board  206 , so that the heat producing components  208  face towards interior surfaces of enclosure  100 . For example, the heat producing components  208  of power supply board  202  may face towards the interior surface of bottom surface  106  of enclosure  100 , while the heat producing components  208  of processor board  204  may face towards the interior of top surface  104  of enclosure  100 . 
         [0025]    Edges of power supply board  202  and processor board  204  may abut portions of the interior surface of enclosure  100 , and those boards may also be clamped to enclosure  100 , while sensor board  206  is not clamped to enclosure  100 . Thermal pads  216 , such as silicon thermal pads, may be disposed between enclosure  100  and the edges of power supply board  202  and processor board  204  to extract heat from power supply board  202  and processor board  204 , and to electrically insulate power supply board  202  and processor board  204  from contact with surfaces of enclosure  100 , thereby preventing possible problems such as damaging the components disposed on power supply board  202  and processor board  204  due to, for example, ground plane shorting. Thus, thermal pads  216  may be disposed between conductive material on the surfaces of processor board  204  and power supply board  202  and portions of the interior of enclosure  100 . 
         [0026]    Gap filler thermal pads  220 , such as silicon gap filler thermal pads, may be disposed between heat producing components  208  facing an interior surface of enclosure  100  and one or more portions of that surface in the interior of enclosure  100 , to directly extract heat from those heat producing components  208  to the environment via enclosure  100 . For example, gap filler thermal pad  220  may be disposed between heat producing components  208  disposed on processor board  204  and a portion of top surface  104  of enclosure  100 , and between heat producing components  208  disposed on power supply board  204  and a portion of bottom surface  106  of enclosure  100 . 
         [0027]    Gap filler thermal pads  220  may be compressed by about 40% between heat producing components  208  and the portion of the interior surface of top surface  104  to achieve optimal thermal transfer from the heat producing components  208  to enclosure  100 . To ensure uniform compression of the thermal pads, the interior surfaces of enclosure  100 , such as the interior surfaces of top surface  104  and bottom surface  106  may include protrusions  120  of variable height, so that gap filler thermal pads  220  disposed between those protrusions  120  and heat producing components  220  of different heights can be equally compressed by about 40%. Thermal pads  216  and gap filler thermal pads  220  may also enhance vibration damping of processor board  204  and power supply board  202 . 
         [0028]      FIGS. 3A-3B  are plan views illustrating an example processor board according to aspects of the disclosure.  FIG. 3C  is a cross-section view illustrating an example processor board according to aspects of the disclosure. As shown in  FIG. 3A , processor board  206  may be a printed circuit board (PCB) and may include fastening points  316  where processor board  206  is mounted to enclosure  100 . Processor board may include surface  302 , which may be the surface of processor board  204  that faces the interior surface of top surface  104  of enclosure  100 . Heat producing components such as processor  304 , flash memory  306 , double data rate (DDR) memory  308 , and power management integrated circuit (PMIC)  310  may be disposed on surface  302 . Processor  304 , flash memory  306 , DDR memory  304 , and PMIC  310  may be arranged on surface  302  to evenly distribute the heat produced by those components and to optimize the placement of hot spots. 
         [0029]    Surface  302  of processor board  204  may also include thermal pads  312 . Thermal pads  312  may include thermal pads  216  and may be disposed on surface  302  on top of exposed conductive material, such as exposed copper (not shown), so that thermal pads  312  may conduct the heat from the exposed conductive material to enclosure  100 . Thermal pads  312  may also provide enhanced vibration damping of processor board  204 . Surface  302  may also include holes  314  that may be filled with thermal epoxy to connect the exposed copper to a ground plane (not shown) for processor board  204 . Similar to gap filler thermal pads, such as gap filler thermal pad  220  shown in  FIG. 2 , thermal pads  312  may also be compressed by about 20% near fastening points  316  to optimize heat transfer to enclosure  100 . 
         [0030]    As shown in  FIG. 3B , processor board  204  may include surface  320  on the opposing side of processor board  204  from surface  302 . As can be seen, mounting points  316  may be hollow areas of processor board  204 , so they may carry through both surface  302  and surface  320  of processor board  204 . Although surface  320  may face towards sensor board  206  and heat sensitive components  210 , one or more heat producing components, such as low dropout (LDO) regulator  322  may be disposed on surface  302 . Heat generating components disposed on surface  320  of processor board  204  may generally produce much less heat than heat generating components disposed on surface  302 , such as processor  304 , and thus may only have less effect on the temperature of heat sensitive components  210 . 
         [0031]    As shown in  FIG. 3C , processor board  204  may include a ground plane  324  between surface  302  and surface  320 . Ground plane  324  may be made of copper and may appear as an infinite ground potential to signals. Heat producing components  208  on surface  302  and surface  320  may directly connect to ground plane  324 , while holes  314  filled with thermal epoxy may connect exposed conductive material on surface  302  to ground plane  324 . 
         [0032]      FIGS. 4A-4B  are plan views illustrating an example power supply board according to aspects of the disclosure.  FIG. 4C  is a cross-section view of an example power supply board according to aspects of the disclosure. As shown in  FIG. 4A , power supply board  202  may be a printed circuit board and may include fastening points  408  where power supply board  202  is mounted to enclosure  100 . Power supply board  202  may include surface  402 , which may be the surface of power supply board  204  that faces away from the interior surface of bottom surface  106  of enclosure  100 , and faces towards sensor board  206  when power supply board  202  is mounted in enclosure  100 . Heat producing components such as catch diode  410 , DC-DC converter  412 , and MOSFET diodes  416  may be disposed on surface  402 . Although these heat producing components face towards sensor board  206  when mounted in enclosure  100 , these heat producing components may produce less heat than the heat producing components on the opposite surface of power supply  202 . 
         [0033]    Thermal pads  406  may also be disposed on surface  402  over exposed conductive material (not shown), so that thermal pads  406  may conduct the heat from those exposed conductive material to enclosure  100 . Thermal pads  406  may also provide enhanced vibration damping of power supply board  202 . Surface  402  may also include holes  418  that may be filled with thermal epoxy to connect the exposed conductive material to a ground plane (shown in  FIG. 4C ) for power supply board  406 . Similar to gap filler thermal pads, such as gap filler thermal pad  220  shown in  FIG. 2 , thermal pads  406  may also be compressed by about 40% near fastening points  408  to optimize heat transfer from power supply board  202  to enclosure  100 . 
         [0034]    As shown in  FIG. 4B , power supply board  202  may include surface  420  on the opposing side of power supply board  202  from surface  402 . Surface  420  may be the surface of power supply board  202  that faces the interior surface of bottom surface  106  shown in  FIG. 2 , of enclosure  100 , and thus faces away from sensor board  206 . Heat producing components such as computer automotive network (CAN) transceivers  422  and low dropout regulator  424  may be disposed on surface  402 . In general, these heat producing components disposed on surface  420  may generate much more heat than heat producing components disposed on surface  402  of power supply board  202 . 
         [0035]    Thermal pads  406  may also be disposed on surface  420  over exposed conductive material (not shown), so that thermal pads  406  may conduct the heat from those exposed conductive material to enclosure  100 . Thermal pads  406  may also provide enhanced vibration damping of power supply board  202 . Surface  402  may also include holes  418  that may be filled with thermal epoxy to connect the exposed conductive material to a ground plane (shown in  FIG. 3C ) for power supply board  406 . Similar to silicon based thermal pads, such as thermal pad  216  shown in  FIG. 2B , thermal pads  406  may also be compressed by about 20% near fastening points  408  to optimize heat transfer from power supply board  202  to enclosure  100 . 
         [0036]    As shown in  FIG. 4C , power supply board  202  may include a ground plane  426  between surface  402  and surface  420 . Ground plane  426  may be made of copper and may appear as an infinite ground potential to signals. Heat producing components  208  on surface  402  and surface  420  may directly connect to ground, while holes  418  filled with thermal epoxy may connect exposed conductive material on surface  402  and surface  420  to ground plane  426 . 
         [0037]      FIGS. 5A-5B  illustrate views of an example sensor board according to aspects of the disclosure. As shown in  FIG. 5A , one or more heat sensitive components such as magnetometer  506 , accelerometer  508 , and gyro  510  are disposed on surface  502  of sensor board  206 . Surface  502  of sensor board  206  may face towards processor board  204  and therefore faces away from power supply board  202 . One or more heat producing components may also be disposed on surface  502  of surface  206 . For example, heat producing components such as analog to digital converter  512  and operational amplifier  514  may be disposed on surface  502 . Although one or more heat producing components may be operably coupled to sensor board  206 , the heat producing components coupled to sensor board  206  may generally produce much less heat than heat producing components coupled to power supply board  202  or processor board  204 . The heat producing components and the heat sensitive components may be uniformly spread on sensor board  206 . 
         [0038]    As shown in  FIG. 5B , surface  520  of sensor board  206  is on the opposite side of sensor board  206  from surface  502 , and one or more heat sensitive components may also be disposed on surface  520  of sensor board  206 . For example, heat sensitive components such as gyroscopes  522  and  524  may be disposed on surface  520 . One or more heat producing components may also be disposed on surface  520  of sensor board  206 . For example, heat producing components such as low dropout regulator  526  may be disposed orthogonal to surface  520 . Surface  520  of sensor board  206  may face towards power supply board  202  and away from processor board  204 . 
         [0039]    Sensor board  206  may also include dampers  212 , such as elastomeric dampers, that are coupled to enclosure  100  to dampen the vibration felt by sensors on sensor board  206  and to further isolate the sensors from heat generating components. 
         [0040]    Various aspects of the disclosure have been described. These and other aspects are within the scope of the following claims.