Abstract:
A system and method for building an electronic system with line-replaceable units (LRUs) is presented. The system includes a first LRU electronic module with a first connector on a side of the first LRU electronic module and a second LRU electronic module with a second connector on a side of the second LRU electronic module. To build the electronic system, the first connector on the first LRU electronic module is connected to the connector on the second LRU electronic module to form a first LRU electronic module and a second LRU electronic module combination with the first connector and the second connector interior to the module combination formed by the first LRU electronic module and the second LRU electronic module. The first connector and the second connector cannot be seen from outside the module combination formed by the first LRU electronic module and the second LRU electronic module.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application claims priority from U.S. Provisional Application Ser. No. 61/630,631, filed Dec. 14, 2011; the disclosure of which is incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of Invention 
     The current invention relates generally to apparatus, systems and methods for connecting together electronic equipment. More particularly, the apparatus, systems and methods relate to connecting line-replaceable units (LRUs) together. Specifically, the apparatus, systems and methods provide for connecting electronic modules together using hidden connectors and/or an elongated bridge connectors. 
     2. Description of Related Art 
     Many electronics packaging approaches are in use today, each having advantages and disadvantages. For applications that require modularity, efficient cooling, high degree of structural integrity, low cost, minimum size, module to module interconnects and host interfaces on a common face, the options are few. One common approach is the single box approach with installed shop replaceable units (SRUs) and side wall heat exchangers. This approach has significant costs involved in producing the chassis and the interconnect. A packaging approach with modules stacked front to back results in serial cooling inefficiencies and space penalties for interconnects front to back and limited access to a host front panel. A need, therefore, exists for a module packing approach with improved space and cooling characteristics. 
     SUMMARY 
     In the preferred embodiment, an adaptable slice/side-to-side modular approach allows electronic modules to receive interconnect directly from the front panel. Side finned heat exchangers can provide parallel cooling front to back. Module to module interfaces are accomplished through side blind mating connectors and interconnection is accomplished through module front panel connections and cables. Minimal costs associated with interconnection are achieved with minimal volume allocation. Additionally, this adaptable slice approach allows, for example, a radio or other device to be upgraded with new and different slices to address different applications, functions and host interfaces while maintaining commonality with core sections of the radio. 
     The preferred embodiment can also be configured as a system built with line-replaceable units (LRUs). The preferred embodiment includes a first LRU electronic module with a first connector on a side of the first LRU electronic module and a second LRU electronic module with a second connector on a side of the second LRU electronic module. The second connects to the first connector when the first LRU electronic module is connected to the second LRU electronic module to form a first and second LRU electronic module combination. The first and second connectors are completely interior to the module combination when it is connected together. 
     In some configurations of the preferred embodiment, a third connector can be located on a side of the second LRU electronic module. The system can include a third LRU electronic module with a fourth connector on a side of the third LRU electronic module and it can connect to the third connector when the second LRU electronic module is connected to the third LRU electronic module. The third connector and the fourth connector are completely interior to an LRU module combination formed by the first LRU electronic module, the second LRU electronic module and the third LRU electronic module. The connections between the first and second connectors and the third and fourth connectors are completely hidden from view when the combination of the first, second and third modules are attached together. 
     Another configuration of the electronic system built with LRUs includes notches in the first, second and third LRU electronic modules. An elongated bridge connector can be placed in the first, second notch and third notches and electrically connects together the first LRU electronic module to the third LRU electronic module through the bridge connector. The elongated bridge connector passes through a notched area of the second LRU electronic module and does not electrically connect to the second LRU electronic module. However, fastening devices connect the elongated bridge connector to the second LRU electronic module. 
     Another configuration of the preferred embodiment includes a fan adapted to cool the first, second and third LRU electronic modules. The fan spans across the first LRU electronic module, the second LRU electronic module and the third LRU electronic module. First, second and third patterns of cooling fins are located respectively in each of the first, second and third LRU electronic modules. The first pattern of cooling fins is different than the second pattern of cooling fins, and the second pattern of cooling fins is different than the third pattern of cooling fins. This provides for cooling fins for each of the three LRU electronic modules to have custom cooling in areas where it is most needed. In operation, the fan pulls air across the first pattern of cooling fins, the second pattern of cooling fins and the third pattern of cooling fins. 
     In general, when the electronic system built with LRUs is assembled the first, second and third LRU electronic modules to form an LRU module combination that is generally rectangular in shape. The electronic system can be a radio with the first LRU electronic module being a power supply, the second LRU electronic module being a radio core, and the third LRU electronic module being a power amplifier. The radio created using LRU electronic modules can be mounted in an electronic chassis. 
     Another configuration of the preferred embodiment is a method for connecting electronic modules that are line-replaceable units (LRUs). The method begins by aligning a connector on the side of a first electronic module with a connector on the side of a second electronic module. The first electronic module and the second electronic module are pushed together so that the connector on the side of a first electronic module is electrically connected to the connector on the side of a second electronic module. When the first electrical module and the second electrical module are connected together, the connector on the right side of a first electronic module and the connector on the left side of a second electronic module are hidden from view and are connected without requiring any cables. 
     The method can optionally perform some other tasks. For example, the method can install a fan that spans both the first electrical module and the second electrical module. The fan pulls air through the first electronic module and the second electronic module. The routes that air travels through both modules can be custom designed so that air routed through the first electronic module is routed in a way that is best for the first module and air is routed through the second electronic module differently that the first electronic module but in a way that best for the second module. An elongated connector bridge can be placed in notches formed in the first electrical module and the second electrical module. The connector bridge is elongated with a first and a second end with connectors located at the first end and the second end. The connector located at the first end of the connector bridge is connected to a connector located in the notch of the first electronic module and the connector located at the second of the connector bridge end is connected to a connector located in the notch of the second electronic module. The first electrical module and the second electrical module can be fastened together to create an assembled electronic module that can be installed into an electronic chassis. For example, the modules can be fastened together with threaded fastening devices such as bolts or screws. 
    
    
     
       BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS 
       One or more preferred embodiments that illustrate the best mode(s) are set forth in the drawings and in the following description. The appended claims particularly and distinctly point out and set forth the invention. 
       The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate various example methods, and other example embodiments of various aspects of the invention. It will be appreciated that the illustrated element boundaries (e.g., boxes, groups of boxes, or other shapes) in the figures represent one example of the boundaries. One of ordinary skill in the art will appreciate that in some examples one element may be designed as multiple elements or that multiple elements may be designed as one element. In some examples, an element shown as an internal component of another element may be implemented as an external component and vice versa. Furthermore, elements may not be drawn to scale. 
         FIG. 1  illustrates a right side isomeric view of the preferred embodiment of an electronic system built with line-replaceable units (LRUs). 
         FIG. 2  illustrates a right side exploded isomeric view of the preferred embodiment of the electronic system built with LRUs. 
         FIG. 3  illustrates a bottom side exploded perspective view of the preferred embodiment of the electronic system built with LRUs. 
         FIG. 4  illustrates an embodiment of a method for connecting electronic modules that are LRUs. 
     
    
    
     Similar numbers refer to similar parts throughout the drawings. 
     DETAILED DESCRIPTION 
       FIG. 1-3  illustrate an example electronic system  1  that includes three electronic modules  3 A-B. The electronic modules  3 A-C are sometimes called “slices”. For example, the electronic system  1  can be radio system where electronic module  3 A is a radio power supply, electronic module  3 B is the core radio and electronic module  3 C is the power amplifier of the radio. In some configurations of the preferred embodiment, the electronic modules  3 A-C can be connected together to form the electronic system  1  and then this system can be plugged or mounted into an electronic chassis housing a larger electronic system. Each electronics module  3 A-C has a respective top side  5 A-C, bottom side  7 A-C, front side  9 A-C, back side  11 A-C, left side  13 A-C and right side  15 A-C. Each module  3 A-C can also have one or more connectors  17  on the front to allow it to be connected to a host system. Of course, the electronic system  1  could have more than three electronic modules or as few as two electronic modules. 
     In the preferred embodiment, the electronic modules  3 A-C can be line-replaceable (or lowest-replaceable) units (LRUs) or line-replaceable components (LRCs). The electronic modules  3 A-C can also be referred to as a first LRU electronic module  3 A, a second LRU electronic module  3 B and a third LRU electronic module  3 C. Line (or lowest) replaceable units (LRUs) are modular components used in, for example, airplanes, ships, vehicles, spacecraft and the like. These modules are designed to be replaced quickly at an operating location. A line-replaceable unit (LRU) is usually a sealed unit such as a radio or other auxiliary equipment. LRUs are typically assigned logistics control numbers (LCNs) or work unit codes (WUCs) to manage logistics operations. 
     LRUs improve maintenance operations, because they can be stocked and replaced quickly from on-site inventory, restoring the system to service, while the failed (unserviceable) LRU is undergoing maintenance. Because they are modular, they also reduce system costs and increase quality, by centralizing development across different models of vehicles. The term LRU has been in use for decades, For example the military document MIL-PRF-49506, Notice 1 of 18 Jan. 2005, the Performance Specification for Logistics Management Information defines an LRU as: “An LRU is an essential support item which is removed and replaced at the field level to restore the end item to an operational ready condition. Conversely, a non-LRU is a part, component, or assembly used in the repair of an LRU, when the LRU has failed and has been removed from the end item for repair.” 
     LRUs are designed to specifications to assure that they can be interchanged, especially if they are from different manufacturers. Usually a class of LRUs will have coordinated environmental specifications (i.e. temperature, condensation, etc.). However, each particular LRU will also have detailed specifications describing its function, tray size, tray connectors, attachment points, weight ranges, etc. It is common for LRU trays to have standardized connections for rapid mounting, cooling air, power and grounding. The mounting hardware is often manually-removable, standard screw-detent quick-release fittings. Front-mounted electrical connectors are often jacks for ring-locked cannon plugs that can be removed and replaced (R&amp;R) without tools. Specifications also define the supporting tools necessary to remove and replace the unit. Many require no tools, or a standard-sized Frearson screwdriver. Frearson is specified for some vehicles and many marine systems because Frearson screws are not designed to cam-out, and the same screwdriver can be used on many sizes of screws. Many LRUs also have handles, and specific requirements for their bulk and weight. LRUs typically need to be “transportable” and fit through a door or hatchway. There are also requirements for flammability, unwanted radio emissions, resistance to damage from fungus, static electricity, heat, pressure, humidity, condensation drips, vibration, radiation and other environmental measurements. 
     LRUs may be designed to Aeronautical Radio Incorporated&#39;s (ARINC&#39;s) 700-series standards. The form factor of LRUs comply with ARINC Standards, ARINC 404 and ARINC 600. LRUs are also defined by manufacturers like Airbus and Boeing and by various military organizations. In the military, electronic LRUs are typically designed to interface according to data bus standards such as MIL-STD-1553. On the International Space Station, LRUs are referred to as Orbit Replaceable Units. 
     When assembled the electronic modules  3 A- 3 C can be connected together with fastening devices  19 . For example, the electronic modules  3 A- 3 C can be connected together using complementary bolts that are threaded together near the corners of the electronic modules  3 A-C. When assembled, mounting brackets  21  can be mounted to the electronic system  1  at various positions. For example, Aeronautical Radio Incorporate (ARINC) type of mounting device can be attached to the electronic system. 
     Historically electronic modules were constructed as completed modular units that only provided for electrical connections on their front sides and rear sides. However, the preferred embodiment of the electronic system  1  provides for blind mating connectors that provide for a way to connect the electronic modules  3 A-C together by providing one or more connectors on the right side  15 A-C to be connected to another connector(s) on the left side  13 A-C of another module at a time the modules  3 A-C are connected together. For example,  FIGS. 2 and 3  illustrate a connector  23  on the right side  15 A of electronic module  3 A that is connected to connector  25  on the left side  13 B of electronic module  3 B. Similarly, a connector  27  on the right side  15 B of electronic module  3 B that is connected to connector  29  on the left side  13 C of electronic module  3 C. These connectors may be pairs of male and female connectors or other types of electronic connectors. Preferably, the connectors are each rigidly attached to their respective electronic modules  3 A-C an positioned so that when the electronic modules  3 A-C are properly positioned and connected together to form the electronic system  1  that the pairs of respective connectors are each properly aligned and then fastened together. One or more of the electronic modules  3 A-C can contain holes  64  and/or guide pins  62  to further align and assist with connecting the modules and connectors to each other. 
     The electronic system  1  can also include an electronic connector bridge  31  as best seen in  FIG. 2 . The electronic connector bridge  31  is used to make further electrical connections between two different electronic modules  3 A-C. For example, the illustrated electronic connector bridge  31  is placed in notches  33 A-C located in the bottom sides  7 A-C of the electronic modules  3 A-C. The electronic connector bridge  31  contains connectors  35 A,  35 B with required wiring between these connectors  35 A, and  35 B. When the electronic system  1  is assembled, the connectors  35 A,  35 B of the electronic connector bridge  31  are connected to complementary connectors  36 A,  36 C adjacent upper portions of the notches. In the preferred embodiment, the electronic connector bridge is formed with a solid body portion  47  that includes a first portion  47 A and a second portion  47 B that are connected together and house internal wiring that connects connectors  35 A and  35 B together. The electronic connector bridge  31  is formed with a top side  49 A, bottom side  49 B, front side  49 C, back side  49 D, right side  49 E, and left side  49 F. The electronic connector bridge  31  can have recessed areas  51  between where the top side  49 A meets the front side  49 C and the back side  49 D. It can have other recessed areas where the bottom side  49 B meets the front side  49 C and the back side  49 D. Screws  55  or other fastening devices can be located in these recessed areas  51  that can be used to attach the electronic connector bridge  31  to one or more of the electronic modules  3 A-C. In other configurations, these screws can be or can act like guide pins for aligning the electronic connector bridge  31  with the electronic modules  3 A-C while attaching it to them. The electronic connector bridge  31  can also contain one or more guide pins  57  used solely for that purpose. 
     The Figures illustrate one example using an electronic connector bridge  31  to electrically connect the left electronic module  3 A to the right electronic module  3 C; however, in other examples and configurations the central electronic module  3 B could be connected to the left electronic module  3 A and/or right electronic module  3 C. Of course if more than three electronic modules are used, then an electronic connector bridge could span any number of those electronic modules and electrically connect any number of those electronic modules together. Also, more than one electronic connector bridge could be used in the electronic system  1 . Additionally, the electronic connector bridge  31  could be located in notches in the top sides  5 A-C or in other sides of the electronic modules  3 A-C. 
     The electronic system  1  further includes a fan  37  with a power connector  39  the can be plugged into the power supply module  3 A to provide power for the fan  37 . The fan  37  spans all three electronic modules  3 A-C in the preferred embodiment. In other configurations, the fan  37  may span a different number of electronic modules or can span a portion of a number of electronic modules making up an electronic system  1 . When the system  1  is assembled, the fan  37  fits within fan notches  41 A-C or cutouts in the electronic modules  3 A-C. The fan  37  can be fastened to the electronic modules  3 A-C with bolts or fastened to the electronic modules  3 A-C in another appropriate way. 
     Each electronic module has air input openings  43 A-C in their front sides  9 A-C that allow the fan  37  to pull cooling air into through the electronic system  1  when the electronic system  1  is assembled and functioning. When the electronic system  1  is disassembled as shown in the exploded views of  FIGS. 2 and 3  these opening appear as notches. Air passes from the openings  43 A-C through guide routes as guided by guide fins  45 A-C until the air exits out the rear back sides  11 A-C of the electronic modules  3 A-C. In other configurations, the fan might not span all electronic modules  3 A-C if some of the electronic modules  3 A-C do not need air cooling and in other configurations air may flow from the rear back sides  11 A-C to the front sides  7 A-C or can enter and exit the electronic system from other places. By having a modular electronic system  1  it is now possible for each electronic module  3 A-C to independently route its cooling air through its own module in a way that best cools each module. 
     As mentioned earlier and now summarized here, the preferred embodiment also provides parallel cooling front to back via module side finned heat exchangers. Module to module interfaces are accomplished through side blind mating connectors and interconnection is accomplished when electronic module slices are connected together. Therefore, minimal costs associated with interconnection are achieved with minimal volume allocation because no interconnect cables are needed. Additionally, this adaptable electronic module slice approach allows, for example, a radio or other device to be upgraded with new and different slices to address different applications, functions and host interfaces while maintaining commonality with core sections of the radio. 
     Those skilled in the art will appreciate that the electronics packaging approach of this invention provides low cost interconnect, even cooling through separate finned heat exchanger for each module and low volume allocated to interconnect. 
     Example methods may be better appreciated with reference to flow diagrams. While for purposes of simplicity of explanation, the illustrated methodologies are shown and described as a series of blocks, it is to be appreciated that the methodologies are not limited by the order of the blocks, as some blocks can occur in different orders and/or concurrently with other blocks from that shown and described. Moreover, less than all the illustrated blocks may be required to implement an example methodology. Blocks may be combined or separated into multiple components. Furthermore, additional and/or alternative methodologies can employ additional, not illustrated blocks. 
       FIG. 4  illustrates a method  400  for connecting electronic modules that are line-replaceable units (LRUs). The method  400  begins by aligning a connector and hole on the right side of a first electronic module with a connector and alignment pin on the left side of a second electronic module, at  402 . The first electronic module and the second electronic module are pushed together, at  404 , so that the connector on the right side of a first electronic module is electrically connected to the connector on the left side of a second electronic module. When the first electrical module and the second electrical module are connected together, the connector on the right side of a first electronic module and the connector on the left side of a second electronic module are hidden from view and are connected without requiring any cables. 
     The method  400  can optionally perform some other tasks. For example, the method can install a fan, at  406 , that spans both the first electrical module and the second electrical module. The fan pulls air through the first electronic module and the second electronic module. The routes that air travels through both modules can be custom designed so that air routed through the first electronic module is routed in a way that is best for the first module and air is routed through the second electronic module differently that the first electronic module but in a way that is best for the second module. An elongated electronic connector bridge can be placed in notches formed in the first electrical module and the second electrical module, at  408 . The electronic connector bridge is elongated with first and second ends with connectors located at each end. At  410 , the connector located at the first end of the electronic connector bridge is connected to a connector located in the notch of the first electronic module and the connector located at the second of the electronic connector bridge end is connected to a connector located in the notch of the second electronic module. The first electrical module and the second electrical module can be fastened together, at  412 , to create an assembled electronic module that can be installed into an electronic chassis. For example, the modules can be fastened together with threaded fastening devices such as bolts or screws. 
     In the foregoing description, certain terms have been used for brevity, clearness, and understanding. No unnecessary limitations are to be implied therefrom beyond the requirement of the prior art because such terms are used for descriptive purposes and are intended to be broadly construed. Therefore, the invention is not limited to the specific details, the representative embodiments, and illustrative examples shown and described. Thus, this application is intended to embrace alterations, modifications, and variations that fall within the scope of the appended claims. 
     Moreover, the description and illustration of the invention is an example and the invention is not limited to the exact details shown or described. References to “the preferred embodiment”, “an embodiment”, “one example”, “an example”, and so on, indicate that the embodiment(s) or example(s) so described may include a particular feature, structure, characteristic, property, element, or limitation, but that not every embodiment or example necessarily includes that particular feature, structure, characteristic, property, element or limitation. Furthermore, repeated use of the phrase “in the preferred embodiment” does not necessarily refer to the same embodiment, though it may.