Abstract:
An enclosure ( 10 ) contains an APU ( 12 ) and an electrical distribution system ( 14 ) to form a self-contained module that can be mounted at any suitable location on a truck&#39;s exterior, eliminating significant portions of the wire/cable routing that would otherwise typically be required.

Description:
FIELD OF THE INVENTION 
       [0001]    This invention relates generally to electrical systems of motor vehicles, especially large motor vehicles like highway trucks. More particularly, the invention relates to a truck that has an auxiliary power unit (APU) for generating AC electric power. 
       BACKGROUND OF THE INVENTION 
       [0002]    A highway truck that has a sleeper cab may also have an APU that generates electric power, typically at times when the engine that propels the truck is shut off. Because the engines of most highway trucks use diesel fuel, the engine in a typical APU is a diesel engine that draws diesel fuel from the truck&#39;s fuel tanks. 
         [0003]    The APU diesel engine powers an electric generator that develops typical household AC voltage, regulated 120 VAC, 60 hz. Electrical devices and accessories, many of which would be considered common household accessories, can be plugged into receptacles in a truck sleeper compartment that are connected to the regulated AC voltage. The regulated AC voltage can also be used to charge the truck&#39;s battery bank. 
         [0004]    Various APU models are commercially available from different manufacturers. A truck manufacturer or user who wants to equip a truck with an APU must determine an appropriate mounting location for the unit. The manufacturer/user must also determine an appropriate mounting location for a power control unit that is needed to interface the APU with the vehicle&#39;s electrical system, and must then make various wiring connections between the units and various connections with the vehicles electrical system. 
         [0005]    The routing of wiring on a truck can be an added expense of incorporating an APU in the truck because of the amount of wiring needed and the time required to install the wiring and both units. Out of necessity and/or because of space limitations, the wiring may have to be routed in locations where shielding and/or other extra protection is needed. 
       SUMMARY OF THE INVENTION 
       [0006]    One aspect of the present invention relates to a more convenient and efficient way to incorporate an APU in a large truck. This improvement is accomplished by making the electric power distribution system self-contained within an APU. 
         [0007]    This eliminates significant portions of the wire/cable routing that would typically be required when an APU and power distribution unit are separate modules mounted at different locations in a truck. 
         [0008]    In accordance with the present invention, a battery charger, Automatic Transfer Swtich (ATS), fuses, relays, wiring, and other devices are arranged inside an enclosure that further houses a diesel engine that operates an AC generator as an APU. 
         [0009]    One general aspect of the invention relates to a truck comprising a DC electrical system comprising a battery bank, a diesel engine for propelling the truck, and a cab that includes a sleeper compartment. 
         [0010]    An APU comprises an enclosure containing a) an AC generator driven by an auxiliary diesel engine for providing auxiliary electric power for the truck, b) a controller for the auxiliary engine, and c) an electrical distribution system for distributing electric power within the enclosure to satisfy electrical loads in the truck remote from the enclosure by selectively using external shore power and auxiliary power from the generator. 
         [0011]    The electrical distribution system comprises an automatic transfer switch for switching AC shore power to the electrical loads when shore power is being supplied to the enclosure and switching the electrical loads to auxiliary power from the generator when shore power is not being supplied to the enclosure, and a battery charger operated either by auxiliary electric power from the generator or shore power for charging the battery bank 
         [0012]    The foregoing, along with further aspects, features, and advantages of the invention, will be seen in the following disclosure of a presently preferred embodiment of the invention depicting the best mode contemplated at this time for carrying out the invention. The disclosure includes a drawing, briefly described as follows. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]      FIGS. 1A and 1B  show an arrangement of components within the interior of an enclosure in accordance with principles of the invention, the views being from different directions. 
           [0014]      FIG. 2  is a schematic diagram showing various devices related to the invention in a truck. 
           [0015]      FIG. 3  is a schematic diagram relating components within the interior of the enclosure to each other and to certain external devices. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0016]    The drawings show a module  10  within which are disposed an APU  12  and an electrical distribution system (EDS)  14  in accordance with principles of the present invention. Module  10  is entirely self-contained for mounting at any suitable location on a truck&#39;s exterior.  FIGS. 1A and 1B  show the module&#39;s cover having been removed so that the interior components can be seen. 
         [0017]    APU  12  comprises an AC generator  16  driven by an auxiliary diesel engine  18  for providing auxiliary electric power for the truck. A controller  20  for auxiliary engine  18  is mounted on a power distribution board  22 . Engine  18  comprises various conventional electrical devices that include an oil pressure sensor, a coolant temperature sensor, a speed sensor, glow plugs, and a starter motor. A DPF sensor is associated with a diesel particulate filter in the engine exhaust system. 
         [0018]    A fuel line  24  runs from engine  18  to one of the truck&#39;s fuel tanks  26  that holds fuel for the diesel engine that propels the truck. Fuel is pumped to engine  18  via a fuel pump  27 . The truck&#39;s coolant system provides coolant for auxiliary engine  18  that is circulated by an electric operated coolant pump  28 . 
         [0019]    The truck&#39;s battery bank  30  is connected via a fuse  32  with the engine starter motor and with a battery charger  34  that is a component of electrical distribution system  14 . Within module  10  battery power is supplied through a fuse  36  to a power controller relay and through a fuse  38  to power distribution board  22 . Battery power is supplied directly to a starter relay. Fuses  36 ,  38 , the power controller relay, the starter relay, and a fuel throttle relay are all disposed inside a fuse and relay box  40  within module  10 . 
         [0020]    Electrical distribution system  14  distributes electric power within module  10  to satisfy electrical AC loads  44 ,  46  in the truck remote from the module by selectively switching external AC shore power and auxiliary AC power from generator  16 . The switching is performed by an automatic transfer switch (ATS)  42 . When shore power is being supplied to module  10  via a respective plug connected into one both receptacles  48 ,  50 , ATS  42  switches the electrical AC loads to shore power. When shore power is not being supplied to the receptacles, generator  16  supplies regulated AC via a regulator  52 . 
         [0021]    Battery bank  30  is typically kept charged by the truck&#39;s alternator. However, when the truck&#39;s engine is not running, battery charger  34  can keep the battery bank charged via either shore power or generator  16  when the latter is being operated by auxiliary engine  18 . 
         [0022]    An interface  54  within the sleeper compartment of a truck cab communicates with APU  12  and electrical distribution system  14  via a CAN data link  56  using a defined protocol. When a person uses the interface to start APU  12 , an APU power request message is issued by the interface. Upon regulated AC power being generated, an APU Power Confirm message is sent to the interface. 
         [0023]    The module comprises a structural frame  60  having metal uprights  62 ,  64 , preferably steel, at opposite sides as shown in  FIGS. 1A and 1B . A horizontal beam  66  bridges the upper ends of the two uprights. 
         [0024]    The battery charge is unique in that it can produce  75 A of current in an environment of 85° C. with no ventilation. Power distribution system  14  has a capacity of 6 KW. 
         [0025]    For enabling battery charger  34  to perform in such an environment, the circuitry is housed within its own metal enclosure, preferably aluminum, that mounts directly against a face of beam  66 . Flow of heat generated internally of the battery charger occurs through the aluminum enclosure to the steel beam. 
         [0026]      FIGS. 1A and 1B  show engine  18  to have an airfilter housing with an air inlet  70  that is open to the exterior of the module when the module&#39;s cover is in place. 
         [0027]    Upright  62  has a hole  72  through which engine exhaust passes out of the module. Upright  62  also serves to mount receptacles  48 ,  50  for shore power input to the module. 
         [0028]    While a presently preferred embodiment of the invention has been illustrated and described, it should be appreciated that principles of the invention are applicable to all embodiments that fall within the scope of the following claims.