Solar powered apparatus having a thermally decoupled solar panel for tracking a portable asset

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 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.

DETAILED DESCRIPTION

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. 1is a functional block diagram illustrating exemplary elements of a system for tracking a portable asset. In an embodiment, the system100includes 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 vehicles102aand102b. Additional fleets (not shown) are contemplated, but not shown. Each vehicle102is capable of bi-directional communication using, for example, a bi-directional communications module200. As an example, the bi-directional communications module200ais associated with vehicle102aand the bi-directional communications module200bis associated with vehicle102b. The bi-directional communications module200can typically be mounted vertically on a forward portion of the vehicle102a, as illustrated by bi-directional communications module200a, or can be mounted on the top of the vehicle102b, as illustrated by bi-directional communications module200b. However, other mounting locations are possible. The bi-directional communications module200may include, for example, the capability for satellite communication, terrestrial communication, radio frequency (RF) communication and other communication methodologies. The bi-directional communication module200may 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 module200may 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 vehicle102is in bi-directional communication with a network management center (NMC)108over at least one communication channel. In the example shown inFIG. 1, each vehicle102is in bi-directional communication with the NMC108over a satellite-based communication system104and a terrestrial-based system106. A satellite-based communication system104can employ, for example, a global positioning system (GPS) communication device and a terrestrial-based communication system106can 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 vehicles102using any combination of the satellite communication system104and the terrestrial-based communication system106. In an embodiment, many different types of data are collected and transferred from the vehicles102to the NMC108. 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 vehicles102is processed via the NMC108. The NMC108can be thought of as a data clearinghouse that receives all data that is transmitted to and received from the vehicles102.

The system100also includes a data center112. The data center112illustrates one possible implementation of a central repository for all of the data received from each of the vehicles102. As an example, as mentioned above many different types of data are transmitted from the vehicles102to the NMC108. All of this data is transmitted via connection111to the data center112. The connection111may 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 center112comprises a number of application servers and data stores, an exemplary one of each being illustrated as a server114and a data store118. Details of the operation of the application server114and data store118are 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 store118communicates with a larger data store, referred to as a “data warehouse”152over connection142. In an embodiment, the data warehouse152can be organized in a multiple-database structure, the details of which are not shown herein for simplicity.

The data warehouse152communicates with a data management and display (DM/DISPLAY) application170. In an embodiment, the data management and display application170implements a set of routines that query the data warehouse152over connection162and that receives data from the data warehouse152over connection164. The data management and display application170captures and provides this data in a usable format over connection172for display on a terminal device174. In an embodiment, the data management and display application170is an analysis engine and is associated with an execution system180over a system bus182. In an embodiment, the execution system180includes a processor184and a memory186. The memory can store the routines that are associated with the data management and display application170. In an embodiment, the processor184can execute the stored routines to implement the functionality of the data management and display application170. Although shown as residing within the data center112, the execution system180may reside elsewhere, and indeed may be implemented as a distributed system in which the memory186and the processor184are located in different places. The terminal device174can 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 user176can view the display provided by the terminal device174.

FIG. 2is a schematic diagram illustrating an embodiment of a bi-directional communication module200ofFIG. 1having a thermally decoupled solar panel for tracking a portable asset. The bi-directional communication module200comprises 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 vehicle102(FIG. 1) or may be a shipping container or any other asset. The bi-directional communication module200comprises a main housing202into which a number of components are integrated. The main housing202contains a battery compartment204in which a rechargeable power source, such as a battery206is located. A connector208electrically couples the main housing202to a vehicle power source to power the bi-directional communication module200when it is coupled to an asset that can provide power. The main housing202also comprises a solar panel210which provides power to the bi-directional communication module200when it is not connected to an asset that can provide power. The solar panel210can also provide charging energy to the battery206. The solar panel210is located beneath a protective solar panel window212. A solar panel gasket214hermetically isolates the solar panel210from atmospheric and ambient conditions.

In an embodiment, the main housing202also comprises a GPS antenna216and a cellular communications antenna218. While only GPS and cellular antennas are illustrated inFIG. 2, other types of communication methodologies may also be supported.

FIG. 3is a schematic diagram300illustrating a cross-section of a portion of the bi-directional communication module200shown inFIG. 2. The cross-section includes a portion of the main housing202, the solar panel window212and the solar panel210. A heat spreader plate315is located adjacent the solar panel210. As illustrated, a recess302is formed in the main housing202. The recess302forms a surface304on 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 plate315, the solar panel210and the solar panel window212.

A first standoff type illustrated using reference numeral322comprises a standoff having a rubberized or plasticized element, which is used to locate the heat spreader plate315so as to create an air gap310in the recess302. The height of the standoff322locates the heat spreader plate315and the adjacently located solar panel210with respect to the surface304of the recess302.

A second standoff type is illustrated using reference324. The standoff324includes a grommet which securely and removably mounts the heat spreader plate315in the recess302. A third standoff type, referred to using reference numeral326, comprises internal threads which are designed to receive a screw, an example one of which is illustrated using reference numeral332, a number of which attach the solar panel window212to the main housing202. Details of the standoff types322,324and326will be described below.

FIG. 4is a schematic diagram400illustrating a cross-section of a portion of the main housing202ofFIG. 3. The main housing202contains a solar panel210, which is covered by the solar panel window212. The solar panel gasket214hermetically isolates the solar panel210from atmospheric and ambient conditions. The air gap310separates a lower surface317of the heat spreader plate315from the surface304. The surface304also forms an exterior portion of a structural element that forms a wall of an electronics enclosure402. In an embodiment, the electronics enclosure402houses an electronics assembly, which is referred to as a main circuit card assembly (CCA)404.

During operation, solar radiation, illustrated using directional arrow412, impinges on the solar panel window212, which is substantially transparent to solar radiation. The solar radiation412is transferred to the solar panel210. The solar panel210converts the solar radiation412to electricity to charge the rechargeable power source206(FIG. 2). However, a greenhouse effect occurs between the solar panel window212and the solar panel210, as illustrated using arrows418. This greenhouse effect creates heat between the solar panel window212and the solar panel210. In addition to the heat generated by the greenhouse effect, normal operation of the solar panel210results in heat being generated by the solar panel210. The heat spreader plate315is located adjacent to the solar panel210and is designed to transfer heat from the solar panel210to the air gap310, which helps to dissipate the heat and prevent the heat from reaching the main circuit card assembly404. Heat is removed from the heat spreader plate315by convection to the air located in the air gap310, as depicted by the arrows419. Heat is also removed from the heat spreader plate315by radiation and convection from the exposed portions of the heat spreader plate315to the surface304and other plastic portions of the main housing202, standoffs322and the standoffs324.

In addition to dissipating heat generated by the solar panel210via the heat spreader plate315and the air gap310, a heat flow path414is created through the standoffs322and the standoffs324. Further, radiation and conduction heat flow paths are illustrated using reference numeral416. In accordance with an embodiment of the invention, heat spreader plate315and the air gap310cooperate to prevent heat generated by the operation of the solar panel210from reaching the main CCA404via heat flow path416.

FIG. 5is a plan view500illustrating the recess and standoffs ofFIGS. 3 and 4. As described above, the recess302in the main housing202comprises a surface304on which a number of different standoff types are located. The standoffs locate and secure the heat spreader plate315(not shown) and the solar panel window212(not shown). The first standoff type322comprises a body portion512and a cap514. The body portion512can be molded or otherwise provided or installed as part of the main housing202, while the cap514can be a rubberized, plasticized, or other flexible material that is mounted over the body portion512. The surface317(FIG. 4) of the heat spreader plate315rests on a top surface516of the cap514.

A second standoff type324includes a body portion522and a grommet524. The heat spreader plate315is illustrated in dotted line to show how the grommet is received in a hole in the heat spreader plate315. The grommet524then mounts over a post526formed over the body portion522of the standoff324to mechanically isolate the heat spreader plate315from the main housing202. This mounting structure provides a heat flow path414(FIG. 4) to provide heat transfer from the heat spreader plate315to the main housing202in addition to the heat dissipation provided by the air gap310.

A third standoff type326comprises a body portion532that includes internal threads534. Alternatively, a smooth hole or recess may be formed in the body portion532to receive a self-tapping screw. If threaded, the internal threads534are configured to receive the screw332(FIG. 3) that is passed through holes in the solar panel window212to secure the solar panel window212, the solar panel gasket214and the solar panel210to the main housing202without contacting the heat spreader plate315. The heat spreader plate315is illustrated in phantom line inFIG. 5and the air gap310is illustrated as being between the surface304and the rear surface317of the heat spreader plate315. Heat removal from a rear surface317of the heat spreader plate315, via the airgap310, is illustrated using arrows419.