Abstract:
An apparatus for tracking a portable asset includes a solar panel, an electronics assembly integrated into an enclosure, and a heat spreading assembly adjacent the solar panel, the heat spreading assembly located to form an air gap separating the heat spreading assembly from the electronics assembly such that heat generated by the solar panel is dissipated in the air gap before reaching the electronics assembly.

Description:
DESCRIPTION OF THE RELATED ART 
     Systems for tracking a portable asset generally include a radio transmitter, a global positioning system (GPS) device, or another type of communication device capable of periodically or continuously reporting its geographic location and other metrics relating to the portable asset to a receiving device. 
     In an asset tracking application, an integrated outdoor electronics enclosure can comprise a solar energy based power source, such as a solar panel and electronics that enable asset tracking in circumstances where local power may not be readily or permanently available. For example, a portable communication device that includes a solar panel power source and a satellite communication terminal integrated in a single enclosure can be located on trucks, trailers, shipping containers, cargo containers, railroad cars, or other portable or moveable assets, to determine and periodically or continuously report the position or location of the asset, as well as provide other data about the asset. These assets may be uncoupled from a stable power source for periods of time. The solar power source can be used to charge a portable power source, such as a battery, when the asset is not coupled to a stable power source. 
     Integrating a solar panel on an outdoor electronics enclosure is challenging due to limited physical space being available and because of the added heat load generated by the exposure of the solar panel to the sun. When the solar panel is directly coupled to the system electronics, the solar loading from the solar panel increases the internal temperature of the enclosure and the electronics within the enclosure. The increased temperature can damage and/or exceed the limits of the electronics. 
     Therefore, it would be desirable to minimize the amount of heat transferred from a solar panel to an electronics assembly. 
     SUMMARY 
     In an embodiment, an apparatus for tracking a portable asset comprises a solar panel, an electronics assembly integrated into an enclosure, and a heat spreading assembly adjacent the solar panel, the heat spreading assembly located to form an air gap separating the heat spreading assembly from the electronics assembly such that heat generated by the solar panel is dissipated in the air gap before reaching the electronics assembly. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the figures, like reference numerals refer to like parts throughout the various views unless otherwise indicated. For reference numerals with letter character designations such as “ 102   a ” or “ 102   b ”, the letter character designations may differentiate two like parts or elements present in the same figure. Letter character designations for reference numerals may be omitted when it is intended that a reference numeral to encompass all parts having the same reference numeral in all figures. 
         FIG. 1  is a functional block diagram illustrating exemplary elements of a system for tracking a portable asset. 
         FIG. 2  is a schematic diagram illustrating an embodiment of a bi-directional communication module of  FIG. 1  having a thermally decoupled solar panel for tracking a portable asset. 
         FIG. 3  is a schematic diagram illustrating a cross-section of a portion of the bi-directional communication module shown in  FIG. 2 . 
         FIG. 4  is a schematic diagram illustrating a cross-section of a portion of the main housing of  FIG. 3 . 
         FIG. 5  is a plan view illustrating the recess and standoffs of  FIGS. 3 and 4 . 
     
    
    
     DETAILED DESCRIPTION 
     The word “exemplary” is used herein to mean “serving as an example, instance, or illustration.” Any aspect described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other aspects. 
     In this description, the term “application” may also include files having executable content, such as: object code, scripts, byte code, markup language files, and patches. In addition, an “application” referred to herein, may also include files that are not executable in nature, such as documents that may need to be opened or other data files that need to be accessed. 
     The term “content” may also include files having executable content, such as: object code, scripts, byte code, markup language files, and patches. In addition, “content” referred to herein, may also include files that are not executable in nature, such as documents that may need to be opened or other data files that need to be accessed. 
     As used in this description, the terms “component,” “database,” “module,” “system,” and the like are intended to refer to a computer-related entity, either hardware, firmware, a combination of hardware and software, software, or software in execution. For example, a component may be, but is not limited to being, a process running on a processor, a processor, an object, an executable, a thread of execution, a program, and/or a computer. By way of illustration, both an application running on a computing device and the computing device may be a component. One or more components may reside within a process and/or thread of execution, and a component may be localized on one computer and/or distributed between two or more computers. In addition, these components may execute from various computer readable media having various data structures stored thereon. The components may communicate by way of local and/or remote processes such as in accordance with a signal having one or more data packets (e.g., data from one component interacting with another component in a local system, distributed system, and/or across a network such as the Internet with other systems by way of the signal). 
     In this description, the terms “communication device,” “wireless device,” “wireless telephone,” “wireless communication device,” and “wireless handset” are used interchangeably. With the advent of third generation (“3G”) and fourth generation (“4G”) wireless technology, greater bandwidth availability has enabled more portable computing devices with a greater variety of wireless capabilities. 
     In this description, the term “portable computing device” (“PCD”) is used to describe any device operating on a limited capacity power supply, such as a battery. Although battery operated PCDs have been in use for decades, technological advances in rechargeable batteries coupled with the advent of third generation (“3G”) and fourth generation (“4G”) wireless technology, have enabled numerous PCDs with multiple capabilities. Therefore, a PCD may be a cellular telephone, a satellite telephone, a pager, a personal digital assistant (“PDA”), a smartphone, a navigation device, a smartbook or reader, a media player, a combination of the aforementioned devices, and a laptop computer with a wireless connection, among others. 
       FIG. 1  is a functional block diagram illustrating exemplary elements of a system for tracking a portable asset. In an embodiment, the system  100  includes fleets of vehicles, each fleet having at least one vehicle. However, typically, a fleet could include many tens, hundreds or thousands of vehicles. An example fleet is illustrated as having vehicles  102   a  and  102   b . Additional fleets (not shown) are contemplated, but not shown. Each vehicle  102  is capable of bi-directional communication using, for example, a bi-directional communications module  200 . As an example, the bi-directional communications module  200   a  is associated with vehicle  102   a  and the bi-directional communications module  200   b  is associated with vehicle  102   b . The bi-directional communications module  200  can typically be mounted vertically on a forward portion of the vehicle  102   a , as illustrated by bi-directional communications module  200   a , or can be mounted on the top of the vehicle  102   b , as illustrated by bi-directional communications module  200   b . However, other mounting locations are possible. The bi-directional communications module  200  may include, for example, the capability for satellite communication, terrestrial communication, radio frequency (RF) communication and other communication methodologies. The bi-directional communication module  200  may comprise one part or element of a larger overall asset tracking system that may include one or more modules that may be located inside of the vehicle, or asset to be tracked, and may include additional network, processing, communication and other elements. For simplicity, the bi-directional communication module  200  may also be referred to herein as an “asset tracking device” and an “integrated electronics enclosure.” However, it is understood that the larger overall asset tracking system includes additional components that are not shown for simplicity of illustration. 
     As an example only, each vehicle  102  is in bi-directional communication with a network management center (NMC)  108  over at least one communication channel. In the example shown in  FIG. 1 , each vehicle  102  is in bi-directional communication with the NMC  108  over a satellite-based communication system  104  and a terrestrial-based system  106 . A satellite-based communication system  104  can employ, for example, a global positioning system (GPS) communication device and a terrestrial-based communication system  106  can employ, for example, a cellular-based communication device. Other communication methodologies may also be employed and are known to those skilled in the art. Depending on many factors, data may be exchanged with the vehicles  102  using any combination of the satellite communication system  104  and the terrestrial-based communication system  106 . In an embodiment, many different types of data are collected and transferred from the vehicles  102  to the NMC  108 . Examples of such data include, but are not limited to, vehicle position, vehicle status, cargo status, driver performance data, driver duty status, truck performance data, critical events, messaging and position data, location delivery data, and many other types of data. All of the information that is communicated to and from the vehicles  102  is processed via the NMC  108 . The NMC  108  can be thought of as a data clearinghouse that receives all data that is transmitted to and received from the vehicles  102 . 
     The system  100  also includes a data center  112 . The data center  112  illustrates one possible implementation of a central repository for all of the data received from each of the vehicles  102 . As an example, as mentioned above many different types of data are transmitted from the vehicles  102  to the NMC  108 . All of this data is transmitted via connection  111  to the data center  112 . The connection  111  may comprise any wired or wireless dedicated connection, a broadband connection, or any other communication channel configured to transport the data. 
     In an illustrative embodiment, the data center  112  comprises a number of application servers and data stores, an exemplary one of each being illustrated as a server  114  and a data store  118 . Details of the operation of the application server  114  and data store  118  are omitted as they are known to those skilled in the art. Although not specifically mentioned, each application server and data store includes a processor, memory including volatile and non-volatile memory, operational software, a communication bus, an input/output mechanism, and other operational systems as known in the art. The data store  118  communicates with a larger data store, referred to as a “data warehouse”  152  over connection  142 . In an embodiment, the data warehouse  152  can be organized in a multiple-database structure, the details of which are not shown herein for simplicity. 
     The data warehouse  152  communicates with a data management and display (DM/DISPLAY) application  170 . In an embodiment, the data management and display application  170  implements a set of routines that query the data warehouse  152  over connection  162  and that receives data from the data warehouse  152  over connection  164 . The data management and display application  170  captures and provides this data in a usable format over connection  172  for display on a terminal device  174 . In an embodiment, the data management and display application  170  is an analysis engine and is associated with an execution system  180  over a system bus  182 . In an embodiment, the execution system  180  includes a processor  184  and a memory  186 . The memory can store the routines that are associated with the data management and display application  170 . In an embodiment, the processor  184  can execute the stored routines to implement the functionality of the data management and display application  170 . Although shown as residing within the data center  112 , the execution system  180  may reside elsewhere, and indeed may be implemented as a distributed system in which the memory  186  and the processor  184  are located in different places. The terminal device  174  can be a user interface portal, a web-based interface, a personal computer (PC), a laptop, a personal data assistant (PDA), a dedicated terminal, a dumb terminal, or any other device over which a user  176  can view the display provided by the terminal device  174 . 
       FIG. 2  is a schematic diagram illustrating an embodiment of a bi-directional communication module  200  of  FIG. 1  having a thermally decoupled solar panel for tracking a portable asset. The bi-directional communication module  200  comprises an externally mounted integrated enclosure that resides outside of or on an exterior portion of an asset to be tracked. The asset ma be a vehicle  102  ( FIG. 1 ) or may be a shipping container or any other asset. The bi-directional communication module  200  comprises a main housing  202  into which a number of components are integrated. The main housing  202  contains a battery compartment  204  in which a rechargeable power source, such as a battery  206  is located. A connector  208  electrically couples the main housing  202  to a vehicle power source to power the bi-directional communication module  200  when it is coupled to an asset that can provide power. The main housing  202  also comprises a solar panel  210  which provides power to the bi-directional communication module  200  when it is not connected to an asset that can provide power. The solar panel  210  can also provide charging energy to the battery  206 . The solar panel  210  is located beneath a protective solar panel window  212 . A solar panel gasket  214  hermetically isolates the solar panel  210  from atmospheric and ambient conditions. 
     In an embodiment, the main housing  202  also comprises a GPS antenna  216  and a cellular communications antenna  218 . While only GPS and cellular antennas are illustrated in  FIG. 2 , other types of communication methodologies may also be supported. 
       FIG. 3  is a schematic diagram  300  illustrating a cross-section of a portion of the bi-directional communication module  200  shown in  FIG. 2 . The cross-section includes a portion of the main housing  202 , the solar panel window  212  and the solar panel  210 . A heat spreader plate  315  is located adjacent the solar panel  210 . As illustrated, a recess  302  is formed in the main housing  202 . The recess  302  forms a surface  304  on which a number of structural elements are provided. In an embodiment, the structural elements are referred to as standoffs, a number of different designs of which are provided for locating and mounting the heat spreader plate  315 , the solar panel  210  and the solar panel window  212 . 
     A first standoff type illustrated using reference numeral  322  comprises a standoff having a rubberized or plasticized element, which is used to locate the heat spreader plate  315  so as to create an air gap  310  in the recess  302 . The height of the standoff  322  locates the heat spreader plate  315  and the adjacently located solar panel  210  with respect to the surface  304  of the recess  302 . 
     A second standoff type is illustrated using reference  324 . The standoff  324  includes a grommet which securely and removably mounts the heat spreader plate  315  in the recess  302 . A third standoff type, referred to using reference numeral  326 , comprises internal threads which are designed to receive a screw, an example one of which is illustrated using reference numeral  332 , a number of which attach the solar panel window  212  to the main housing  202 . Details of the standoff types  322 ,  324  and  326  will be described below. 
       FIG. 4  is a schematic diagram  400  illustrating a cross-section of a portion of the main housing  202  of  FIG. 3 . The main housing  202  contains a solar panel  210 , which is covered by the solar panel window  212 . The solar panel gasket  214  hermetically isolates the solar panel  210  from atmospheric and ambient conditions. The air gap  310  separates a lower surface  317  of the heat spreader plate  315  from the surface  304 . The surface  304  also forms an exterior portion of a structural element that forms a wall of an electronics enclosure  402 . In an embodiment, the electronics enclosure  402  houses an electronics assembly, which is referred to as a main circuit card assembly (CCA)  404 . 
     During operation, solar radiation, illustrated using directional arrow  412 , impinges on the solar panel window  212 , which is substantially transparent to solar radiation. The solar radiation  412  is transferred to the solar panel  210 . The solar panel  210  converts the solar radiation  412  to electricity to charge the rechargeable power source  206  ( FIG. 2 ). However, a greenhouse effect occurs between the solar panel window  212  and the solar panel  210 , as illustrated using arrows  418 . This greenhouse effect creates heat between the solar panel window  212  and the solar panel  210 . In addition to the heat generated by the greenhouse effect, normal operation of the solar panel  210  results in heat being generated by the solar panel  210 . The heat spreader plate  315  is located adjacent to the solar panel  210  and is designed to transfer heat from the solar panel  210  to the air gap  310 , which helps to dissipate the heat and prevent the heat from reaching the main circuit card assembly  404 . Heat is removed from the heat spreader plate  315  by convection to the air located in the air gap  310 , as depicted by the arrows  419 . Heat is also removed from the heat spreader plate  315  by radiation and convection from the exposed portions of the heat spreader plate  315  to the surface  304  and other plastic portions of the main housing  202 , standoffs  322  and the standoffs  324 . 
     In addition to dissipating heat generated by the solar panel  210  via the heat spreader plate  315  and the air gap  310 , a heat flow path  414  is created through the standoffs  322  and the standoffs  324 . Further, radiation and conduction heat flow paths are illustrated using reference numeral  416 . In accordance with an embodiment of the invention, heat spreader plate  315  and the air gap  310  cooperate to prevent heat generated by the operation of the solar panel  210  from reaching the main CCA  404  via heat flow path  416 . 
       FIG. 5  is a plan view  500  illustrating the recess and standoffs of  FIGS. 3 and 4 . As described above, the recess  302  in the main housing  202  comprises a surface  304  on which a number of different standoff types are located. The standoffs locate and secure the heat spreader plate  315  (not shown) and the solar panel window  212  (not shown). The first standoff type  322  comprises a body portion  512  and a cap  514 . The body portion  512  can be molded or otherwise provided or installed as part of the main housing  202 , while the cap  514  can be a rubberized, plasticized, or other flexible material that is mounted over the body portion  512 . The surface  317  ( FIG. 4 ) of the heat spreader plate  315  rests on a top surface  516  of the cap  514 . 
     A second standoff type  324  includes a body portion  522  and a grommet  524 . The heat spreader plate  315  is illustrated in dotted line to show how the grommet is received in a hole in the heat spreader plate  315 . The grommet  524  then mounts over a post  526  formed over the body portion  522  of the standoff  324  to mechanically isolate the heat spreader plate  315  from the main housing  202 . This mounting structure provides a heat flow path  414  ( FIG. 4 ) to provide heat transfer from the heat spreader plate  315  to the main housing  202  in addition to the heat dissipation provided by the air gap  310 . 
     A third standoff type  326  comprises a body portion  532  that includes internal threads  534 . Alternatively, a smooth hole or recess may be formed in the body portion  532  to receive a self-tapping screw. If threaded, the internal threads  534  are configured to receive the screw  332  ( FIG. 3 ) that is passed through holes in the solar panel window  212  to secure the solar panel window  212 , the solar panel gasket  214  and the solar panel  210  to the main housing  202  without contacting the heat spreader plate  315 . The heat spreader plate  315  is illustrated in phantom line in  FIG. 5  and the air gap  310  is illustrated as being between the surface  304  and the rear surface  317  of the heat spreader plate  315 . Heat removal from a rear surface  317  of the heat spreader plate  315 , via the airgap  310 , is illustrated using arrows  419 . 
     Although selected aspects have been illustrated and described in detail, it will be understood that various substitutions and alterations may be made therein without departing from the spirit and scope of the present invention, as defined by the following claims.