Abstract:
The present invention is generally related to providing auxiliary power to long-haul trucks and similar types of transportation vehicles, and more particularly related to an easily installed and maintained auxiliary power unit that provides operational levels of electrical power and HVAC services while simultaneously driving a hydraulic system through an incorporated hydraulic pump assembly.

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
       [0001]    This application is a continuation-in-part of the Cagliari et al. utility application, Ser. No. 11/493,495, filed 25 Jul. 2006, the entirety of which is hereby incorporated by reference. 
     
    
     STATEMENTS AS TO THE RIGHTS TO INVENTIONS MADE UNDER FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
       [0002]    Not applicable. 
       REFERENCE TO A “SEQUENCE LISTING,” A TABLE, OR A COMPUTER PROGRAM LISTING APPENDIX SUBMITTED ON A COMPACT DISK 
       [0003]    Not applicable. 
       BRIEF DESCRIPTION OF THE INVENTION 
       [0004]    The present invention is generally related to providing auxiliary power to long-haul trucks and similar types of transportation vehicles, and more particularly related to an easily installed and maintained auxiliary power unit that provides operational levels of electrical power and HVAC services while simultaneously driving a hydraulic system through an incorporated hydraulic pump assembly. 
       BACKGROUND OF THE INVENTION 
       [0005]    Long-haul trucks transport goods over great distances in all parts of the world. In California alone, there are at least 180,000 transport trucks in operation. Since operators of long-haul trucks spend many days at a time on the road, the cabins for such trucks typically include a bed, as well as microwaves, air conditioners and heaters, refrigerators, televisions, stereos and other electrical appliances that require significant amounts of power. Long-haul trucks equipped with this type of cabin are referred to as sleeper berth vehicles. 
         [0006]    In at least thirty states and the District of Columbia, many different types of vehicles, including sleeper berth vehicles, are not allowed to idle their main engines for a period longer than five minutes, which is why more of these vehicles are installing auxiliary power units (APUs) to run in place of the main engine when the drivers are attempting to sleep or making use of the other convenience features of the vehicles. While these laws are more rigorous in some states, such as California, then other states, emissions standards are becoming increasingly more rigorous nationwide. 
         [0007]    Accordingly, a number of companies have begun to supply APUs to provide climate control and 120-volt power, to cut back on fuel consumption and air pollution, to reduce operating hours on the main vehicles engine, and to improve driver comfort and quality of life when on the road. A typical APU consumes about 0.2-0.3 gallons per hour, with significantly lower annual maintenance costs, thereby saving drivers/truck owners more than $6,900 per year in fuel costs alone. In the European Union, where long-haul trucks only idle about 1,800 hours per year, but fuel costs much more per gallon, the idle cost savings alone are over $8,500 per year. 
         [0008]    The APUs currently on the market, however, share certain features and disadvantages. For example, most APUs use small diesel engines for power, but depending on the size of those engines, they may be able to provide only a limited amount of DC power and BTUs/hour for air conditioning and heating. Likewise, many of these engines are installed as an aftermarket addition to the trucks and are directly connected to the main engine so as to share main engine coolant, which can void warranties and prevent maintenance services from being available for the truck until the APU is removed. Some APUs do not provide for AC power because they do not include a generator, while others are noisy, cost too much to maintain, are too large or heavy, or do not provide for easy management and monitoring of the unit by the driver or the fleet owner. One of the biggest shortcomings of existing APUs is that they lack the ability to provide for concurrent power loads, meaning that drivers often have to manually shut off one electrical appliance or cooling/heating source when they want to use something else. In very cold or hot environments, this factor significantly detracts from the quality of the driver&#39;s life and therefore the attractiveness of the APU. 
         [0009]    Hydraulic systems and machinery utilize fluid power to do the desired work. In a hydraulic system, high-pressure liquid (called hydraulic fluid) is transmitted throughout the system to various hydraulic motors and hydraulic cylinders. The hydraulic fluid is controlled directly or automatically by control valves and distributed through hoses and tubes. Hydraulic machinery is popular because of the very large amount of power that can be transferred through small tubes and flexible hoses, and the high power density and wide array of actuators that can make use of this power. 
         [0010]    The heart of a hydraulic system is the hydraulic pump. A hydraulic pump converts mechanical energy into hydraulic energy, and is the driving force of the overall hydraulic system. Hydraulic pump output is usually measured in gallons of hydraulic fluid pumped per minute (gpm=gallons per minute). The hydraulic pump receives mechanical energy from an outside source and in response forces the hydraulic fluid through the system&#39;s various tubes, hoses, reservoirs, and/or hydraulic motors at relatively high pressure in order to do the desired work. The outside source providing mechanical energy to the hydraulic pump can be an electric motor, an engine, or even human manual power in the case of hydraulic hand pumps. 
         [0011]    Hydraulic systems are most often used in heavy equipment, like cranes or excavators, because of the great level of force which may be generated by the pressured hydraulic fluid. Hydraulic systems are also commonly used to control the movement of various components of aircraft, such as extending and retracting landing gear, positioning flaps, operating hoists, and raising and lowering cargo doors. Hydraulic systems are used in lifting and/or transporting heavy items or cargo. Fork-lifts, order-pickers, and other jacketing equipment utilize hydraulic systems to lift or move items too heavy for human workers to lift themselves. 
         [0012]    It would be advantageous to create an efficient APU that can drive a hydraulic system while simultaneously providing HVAC services and electrical power to a long-haul truck cabin. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
         [0013]      FIG. 1  is a perspective view of the front and left side of an APU, without the presently disclosed hydraulic pump assembly, in its service/maintenance position; 
           [0014]      FIG. 2  illustrates an exemplary embodiment of an APU with an attached hydraulic pump assembly in accordance with the present invention; 
           [0015]      FIG. 3  illustrates the same exemplary embodiment of an APU with an attached hydraulic pump assembly in accordance with the present invention illustrated in  FIG. 2 , but viewed from the side; 
           [0016]      FIG. 4  illustrates a perspective view of the back and right side of the APU with an environmental cover and co-located condenser and fan in accordance with the present invention; 
           [0017]      FIG. 5  illustrates a perspective view of the back and right side of the APU with the environmental cover, but without the co-located condenser and fan, in accordance with the present invention; 
           [0018]      FIG. 6  illustrates a perspective view of the front and right side of the APU with the environmental cover and the optional step assembly, in accordance with the present invention; 
           [0019]      FIG. 7  illustrates a perspective view of the front and right side of the frame assembly illustrating a through-the-frame rail installation, in accordance with the present invention; 
           [0020]      FIG. 8  illustrates a perspective view of the front and right side of the frame assembly illustrating a frame rail bracket installation, in accordance with the present invention; 
           [0021]      FIG. 9  illustrates a perspective view of the front and right side of the frame assembly illustrating an installation for pre-drilled frame rails, in accordance with the present invention; 
           [0022]      FIG. 10  is a block diagram illustrating the interconnection between the ECU, the ECU user interface, the main engine battery, the APU engine, the cabin HVAC system, and the hydraulic pump assembly, in accordance with the present invention; 
           [0023]      FIG. 11  is a block diagram illustrating the interaction between the APU engine, the cabin HVAC system, the hydraulic pump, and a hydraulic system, in accordance with the present invention; and 
           [0024]      FIG. 12  illustrates a plan view of an ECU user interface in accordance with the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0025]    The present invention is directed towards an auxiliary power unit that includes a hydraulic pump assembly. An auxiliary power unit (or “APU”) may alternatively be referred to as an alternative power unit, or an alternate power unit. The herein disclosed APU with a hydraulic pump is capable of driving one or more hydraulic systems, such as hydraulic jacketing equipment, in addition to powering one or more truck auxiliary systems, such as driver-area services like HVAC systems and electrical power, for example. In the preferred embodiment of the present invention, the auxiliary power unit (APU) has a lateral dimension of up to approximately 62 centimeters or 24.5 inches, which is small enough to enable it to be mounted in a variety of positions behind the cabin of the truck without interfering with or taking away space from other components of the truck, although APUs of many different sizes could also be utilized in a similar fashion. Typically, the APU would be mounted close to the truck cabin on one of the two frame rails of the truck, as illustrated in  FIGS. 7 ,  8 , and  9 , but the APU could also be mounted between the frame rails or to some other part of the truck. 
         [0026]    Mounting the APU to one of the frame rails provides a very stable mounting environment for the APU due to the structural integrity of the frame rails. The mounting environment also enables easier installation and access to the APU for maintenance and service. Mounting the APU close to the cabin can reduce the cost of the installation by reducing the length of the umbilical cord (described further below) between the APU and the truck cabin where the main controller for the APU is located. Such placement considerations must be balanced against the potential benefits of locating the APU with a hydraulic pump physically closer to the hydraulic system. For example, if the APU will be utilized to drive hydraulic lifting equipment located in the trailer of the truck, near the goods being hauled, then there may be efficiency losses associated with placing the APU, and the attached hydraulic pump, further away from the trailer. In the preferred embodiment of the present invention, a frame rail mounted APU is disclosed that facilitates access for maintenance and service, as further illustrated in  FIGS. 1  and  FIGS. 4-9 . 
         [0027]      FIG. 1  is a perspective view of the front and left side of APU  10  when viewed facing the side of the truck to which the APU  10  is mounted. APU  10  illustrated in  FIG. 1  does not show the hydraulic pump assembly. The APU  10  includes the APU engine  12 , which is a two or three cylinder diesel engine mounted to a frame assembly  14 , which includes a sliding component  16 . The frame assembly  14  is attached to the frame rail  15  of the truck, but the sliding component  16  enables the entire diesel engine  12  to be pulled away from the truck and easily accessed by anyone needing to service the engine, the hydraulic pump, or any other component of the herein described APU. 
         [0028]    As noted,  FIG. 1  illustrates the APU engine  12  without the hydraulic pump assembly, when the sliding component  16  has been pulled away from the frame assembly  14 , such as when it is being serviced. In order for the engine  12  to be pulled away from the truck on the sliding component  16 , certain mechanical and electrical components need to be designed to facilitate this type of movement without breaking down over a number of years. For example, the electrical wiring between the APU  10  and the truck cabin is provided through a spring-shaped umbilical cord consisting of power wires and communication wires. The spring shape of the cord enables it to stretch out when the APU is pulled away from the truck for service, and to shrink back into a smaller size when the APU is in its normal operating position, all without putting undue stress on the wires within the cord. Likewise, the exhaust pipe is connected with a flexible metal hose and a quick-fit connector, rather than welded in place. Additionally, any hydraulic fluid tubes and/or hoses that connect the hydraulic pump assembly (not shown in  FIG. 1 ) to a hydraulic system, such as a lifting system located in the truck&#39;s trailer for example, must be flexible and capable of withstanding the repeated stretching and straining associated with pulling the overall APU away from the truck frame during servicing and pushing the overall APU back into the normal operating position. 
         [0029]    As noted, the APU engine  12  is typically a two or three cylinder diesel engine capable of generating approximately 10-30 horsepower at varying revolutions per minute, such as the YANMAR TNV SERIES engines, although other types and sizes of engines could be utilized. A diesel engine of the indicated power is preferred due to environmental concerns (reduced emissions and noise), economics (better fuel economy while providing more than adequate power) and driver convenience (most long-haul trucks utilize diesel engines, thereby allowing the main engine and the APU to be fueled at the same time). Such a diesel engine also allows for full driver area functionality (HVAC and 110 volt electrical power) while simultaneously driving the hydraulic pump at up to 95% efficiency. Most truck owner/operators prefer to link the APU to the main gas tank(s) for the truck, rather than carry an additional tank for the APU, so using common fuel under such circumstances is essential. It would be preferable, obviously, to provide a separate storage tank for the APU, if the APU engine  12  used a fuel that could not be used by the main truck engine, although this would add significantly to the cost of installing the APU. 
         [0030]    As illustrated in  FIG. 1 , some of the major visible components of the APU engine  12  include a water/coolant radiator  18 , an air cleaner  20 , and fuel filters  22  on the right-hand side of the engine. At the front of the APU engine  12 , driven by the serpentine belt  24  are the engine flywheel  26 , the air conditioning compressor  28 , the AC power generator  30 , and the belt tensioner  31 . The DC power alternator  32  is shown on the back left-hand side of the engine  12 , as is the exhaust pipe  33 . 
         [0031]    A hydraulic pump assembly may be functionally attached to the flywheel  26  shown in  FIG. 1 , or to crankshaft driven components such as a pulley, creating an APU capable of driving a hydraulic system.  FIGS. 2 and 3  illustrate one example of such a configuration. As illustrated in  FIG. 2 , hydraulic pump assembly  201  may be attached on the front side of engine flywheel  26  (which is not visible in  FIG. 2  because it is obscured by the presence of the hydraulic assembly pulley  230  in  FIG. 2 ). Hydraulic assembly pulley  230  may be attached directly onto the face of engine flywheel  26 , as will be apparent to those skilled in the art. Hydraulic assembly belt  220  runs from hydraulic assembly pulley  230  down towards hydraulic pump  210 , which may be bolted onto the lower left portion of APU  10  as positioned in  FIG. 1 . Hydraulic assembly belt tensioner  240  may be utilized to optimize the tension of hydraulic assembly belt  220 , as is known in the art. Hydraulic pump electrical control leads  212  may be run from hydraulic pump  210  to the engine control unit (ECU), which may be utilized to control operation of the hydraulic pump. The engine control unit will be discussed in further detail below. Those skilled in the art will recognize that is possible to achieve substantially similar results by running the hydraulic pump assembly  201  off the back side of the engine, by functionally attaching hydraulic pump  210  to a pulley which itself is functionally attached to the engine&#39;s crankshaft. 
         [0032]      FIG. 3  illustrates a perspective view of the same hydraulic pump assembly illustrated in  FIG. 2 . Hydraulic assembly pulley  230  is attached to engine flywheel  26  by extender  231 . As described above, the hydraulic pump assembly may alternatively be mechanically attached to, and driven by, a pulley attached to the engine&#39;s crankshaft (not shown in the figures). Hydraulic assembly belt  220  runs from hydraulic assembly pulley  230  down to hydraulic pump  210 , which may be bolted to the frame of the APU, somewhat below engine flywheel  26 . Hydraulic pump inlet and outlet ports  215  are also illustrated protruding from hydraulic pump  210  in  FIG. 3 . Inlet and outlet ports  215  may be connected via hydraulic fluid tubes or hoses to the rest of the hydraulic system (not shown in  FIG. 3 ). 
         [0033]    Any sort of suitable hydraulic pump may be utilized as hydraulic pump  210 , and an optimum hydraulic pump choice mostly depends upon the hydraulic system that hydraulic pump assembly  201  is going to be driving. For example, hydraulic lifting equipment used to lift or move goods at the back of a long-haul truck may properly utilize a 5.5 gpm hydraulic pump or a 7 gpm hydraulic pump at  210  of hydraulic pump assembly  201 . A 5.5 gpm hydraulic pump is preferred for use in combination with a 2-cylinder APU engine  12 , producing an APU capable of providing HVAC services (operating/powering an air conditioning compressor and a coolant-based radiator) and electrical power (operating/powering a DC power alternator and an AC power generator) to the truck cabin (the driver-area of the vehicle, which may alternatively be referred to as the human occupied area of the truck) while simultaneously driving the hydraulic pump at 95% efficiency. Additionally, it may be possible to incorporate hydraulic energy storage technology, well known in the art, to the herein disclosed hydraulic pump assembly for an APU in order to operate at higher levels of hydraulic fluid flow (thereby producing more hydraulic power) while utilizing the same 5.5 or 7 gpm hydraulic pump at hydraulic pump  210 . 
         [0034]    As further illustrated in  FIG. 1 , the backside of the air conditioning condenser and fan  34  is shown. A perspective view of the front and right side of the condenser and fan  34  is illustrated in  FIG. 4 . The condenser and fan  34  need not be co-located with the engine  12 , if space in the area of the APU installation is at a premium, or if the owner/operator prefers to move the condenser and fan  34  as far away from the truck cabin as possible so as to reduce noise inside the cabin. 
         [0035]    In such cases, as illustrated in  FIG. 5 , the condenser and fan could be removed from the frame assembly  14 , with the resulting opening being covered by the plate  38 . The coolant lines from the compressor  28  would then be run to wherever the condenser and fan had been relocated in order for the air conditioning system to operate property. The condenser and fan  34  works in conjunction with the compressor  28  to provide approximately 26,000 BTU/hr of air conditioning for the cabin of the truck when the APU  10  is being utilized in place of the truck&#39;s main engine. The generator  30  is configured to provide between 3.7 Kw to 6.0 Kw of AC power, while the alternator  32  is configured to provide approximately 55 Amps of DC power, although different levels of cooling and power could be configured. APU  10  will continue to provide similar levels of heating, cooling, and electrical power while simultaneously driving hydraulic pump assembly  201  via engine flywheel  26  (or via the engine&#39;s crankshaft). 
         [0036]    In the preferred embodiment of the invention, the cabin is also provided with approximately 26,000 Btu/hr of heat through use of heating coolant from the radiator and a heater core. Heat from the engine  12 , for starting and running in cold climates, is provided by a block heater. In  FIG. 11 , the interaction between the APU engine, the cabin HVAC system, and a hydraulic system will be further described. Also, as further described below with respect to the ECU, the air conditioning and heating system (HVAC) and a hydraulic system can be automatically or manually controlled. 
         [0037]      FIGS. 4 and 5  also illustrate the APU  10  covered by its environmental shell  36  (but without the hydraulic pump assembly  201 ), which further reduces the level of noise produced by the APU engine  12 .  FIGS. 4 and 5  show the APU  10  as positioned in its normal operating position. The environmental shell  36  provides protection to the APU engine  12  when the truck is on the road, while allowing sufficient air to move through the shell, such as through screen  40 . A variety of different shells could be used depending on the owner of the truck and the location of the APU  10 . Owner operated trucks that have the APU  10  installed in a visible location may want a visually appealing cover, such as diamond plate metal or chromed metal. When the APU  10  is not visible, or the owner of the truck is less concerned with appearance, a less expensive thermoplastic (or similar type of material) could be used. Of course, when the hydraulic pump assembly is attached to APU engine  12 , the environmental shell  36  may need to be slightly enlarged in order to accommodate the additional components, such as the hydraulic assembly pulley  230 , hydraulic assembly belt  220 , hydraulic belt tensioner  240 , hydraulic pump  210 , or inlet and outlet ports  215 , which may protrude out further from the APU engine  12  than can be accommodated with the standard environmental shell  36 . 
         [0038]    As previously noted, sliding component  16  of the frame assembly  14  enables the entire APU engine  12  to slide out from its operating position on the rollers of the sliding component  16  when it is necessary to maintain and service the APU  10 . To prevent the APU engine  12  from sliding out during operation, the sliding component and engine need to be locked into position, using bolts or some similar form of fixation. The bolt heads should preferably be located at the front of the APU so they can be easily accessed and removed when maintenance or service is required. The environmental shell  36  could also be bolted down, or the tie downs  42  on either side of the shell, connecting the frame assembly  14  to the environmental shell  36 , could be utilized to provide a quick release mechanism for the shell. 
         [0039]      FIGS. 4 and 5  further illustrate a step assembly  44  that could be affixed to the APU  10 , which is better illustrated in  FIG. 6 . The step assembly is optional, but when provided, enables someone to climb the steps on the APU  10  to get on top of the APU  10  or the upper portion of the truck.  FIG. 6  does not show the herein disclosed hydraulic pump assembly  201 , but when a hydraulic pump assembly is utilized, step assembly  44  may also have to be modified to accommodate inlet and outlet ports  215  or other hydraulic pump assembly components. 
         [0040]    As previously noted, in the preferred embodiment of the present invention, the APU  10  is mounted to the frame rail  15  of the truck.  FIGS. 7 ,  8 , and  9  illustrate three ways in which such mounting is achieved. In  FIG. 7 , the frame assembly  14  is affixed to the frame rail  15  by a series of bolts  50  and nuts  52 . The bolts  50  are inserted into holes  53  that have to be drilled through the frame rail  15  for the purpose of mounting the APU  10 . In some applications, it may be desirable to distance the frame assembly  14  from the frame rail, for example to provide extra space for the condenser and fan  34  when that item is mounted to the APU  10  instead of in a remote location, or to provide space necessary for inlet and outlet ports  215  of hydraulic assembly  201 . In such cases, different length spacers  54  could be utilized between the bolts  50  and nuts  52 . When utilizing spacers  54  to create additional space for the APU  10 , caution must be exercised to prevent the APU  10  from extending too far away from the side of the truck, lest it collide with another object when the truck passes by the object. 
         [0041]    Some truck owners object to drilling holes in the frame rails out of concern for the structural integrity of the rails or due to a general unwillingness to make any permanent alterations to the truck&#39;s body. For fleet operators, business arrangements regarding the ownership and/or financing of the trucks can lead to long delays and special permissions being required in order to drill holes in the frame rails. In such cases, the bracket arrangement illustrated in  FIG. 8  can be utilized. As shown in  FIG. 8 , a front bracket  60  is attached to a rear bracket  61 , with the frame rail  15  situated in-between the brackets, by bolts  62  and nuts  64 . The frame assembly  14  is then affixed to the front bracket  60  by the bolts  66  and the nuts  68 . As discussed in  FIG. 7 , spacers  70  could also be utilized to provide extra space for the APU  10 . A wide variety of different means of attaching the frame assembly  14  to the frame rails  15  or the truck could also be utilized. 
         [0042]    In many European countries, the frame rail  15  of the truck is pre-drilled with holes for a number of different reasons, including mounting accessory equipment such as an APU.  FIG. 9  illustrates an example of a pre-drilled frame rail  15 , where the pre-drilled holes do not necessarily line up with the mounting components of the frame assembly  14 . In such a case, conversion brackets  72  would be utilized to form an interface between frame assembly  14  and the frame rail  15 . For example, the frame assembly  14  would be bolted to one side of bracket  72 , with holes in that one side of the bracket designed to line up with holes in the frame assembly  14 , while the other side of bracket  72  would be bolted to the frame rail  15 , with holes in that other side of the bracket designed to line up with holes in the frame rail  15 . 
         [0043]    The APU  10 , the hydraulic pump assembly  201 , and other aspects of the invention are controlled by an engine control unit (ECU) or engine management system (EMS), which is a microprocessor controlled electronic device that enables programmed or external control of the APU engine  12  and other electronically controlled components. ECUs are commonly used to control vehicle engines and are well known in the art. The ECU includes a variety of electrical components on a printed circuit board, including the aforementioned microprocessor that processes inputs from the engine and hydraulic pump assembly sensors in real time and controls the hardware (including all of the electro-mechanical components of the APU, including the in-cabin HVAC system and the hydraulic pump) in accordance with operator inputs and/or programmed instructions in the form of software or firmware. The typical ECU of an engine can read many different sensors associated with the engine and use that information to control various aspects of the engine&#39;s operation. This might include the ignition systems of the engine so as to improve fuel efficiency, regulate power, and lower pollution levels. The ECU can also compensate for many engine operation variables, such as ambient temperature, humidity, altitude, and fuel octane ratings. 
         [0044]    As shown in  FIG. 10 , with respect to the present invention, the ECU  80  is utilized to control various operational aspects of the APU engine  12 , as well as the main engine battery  82  of the truck, the truck&#39;s in-cabin HVAC system  84  associated with the APU, and the hydraulic pump assembly  201 . The ECU  80  is in turn partly or fully controlled by the ECU user interface and control system  86 . Preferably, the ECU user interface and control system  86  is multifunctional, depending on who is using it and how the various interfaces to the control system  86  are provided. For example, the control system  86  can have an electro-mechanical user interface in the cabin of the truck that can be accessed by the driver of the truck. Alternatively, control system  86  can have a separate or an additional electro-mechanical user interface located back in the trailer portion of the truck, close in proximity to a hydraulic lifting system and the goods that need to be lifted. It may also be advantageous to separate the user interface and control system  86  into two user interfaces, one located in the cabin for the driver to control in-cabin HVAC system  84  and other cabin area services (a cabin user interface) and one located in the trailer for controlling a hydraulic lifting system (a hydraulic system user interface). 
         [0045]    This type of user interface for the control system  86  utilizes a simple visual display or electrical touch screen and/or a series of basic tact switches that allow the truck driver to control some basic functions of the APU  10  through the ECU  80 . An example of a user interface with an alphanumeric display and tact switches is further illustrated in  FIG. 12 . Since many truck drivers are older and less comfortable with electronic interfaces than many younger drives, they may prefer toggle switches, rotary switches and encoders, which are the switches typically utilized in modern automobiles and trucks used to control radios and heating/cooling systems. 
         [0046]    In addition to the electro-mechanical user interface, one or more additional types of interfaces, such as a USB interface, are preferably provided, with any and all types of user interfaces being referred to herein as a user interface unless otherwise states. The advantage of the USB interface is that it will enable direct and remote connection of a computer to the ECU  80 . A directly connected computer could be utilized when performing maintenance and service on the truck, or when first installed or upgrading the APU  10 . Remote computer connections, for example, through a wireless Ethernet connection to the ECU  80 , would provide long-range remote diagnosis and maintenance on the APU  10 , as well as computerize setup, upgrade, testing and diagnosis of the APU  10 . Additional wireless connections could be provided through an Internet connection, a Bluetooth connection or even through a cell phone network. Drivers could even be provided with some sort of wireless remote control device, like for a television set, which would enable them to perform simple operations while sitting in a dinner near their truck. 
         [0047]    While the driver&#39;s user interface might be structured to only allow the driver to control some very basic operations, such as turning the APU on and off, setting the temperature for the air conditioning or heating within the truck cabin, turning a fan on or off, turning the hydraulic pump on or off and adjusting hydraulic fluid flow, and perhaps checking on certain basic maintenance items, such as whether the APU is in need of oil, computer-based user interfaces could provide a broader range of control options. Irrespectively of the control means, all such control devices would perform certain similar functions, such as setting operating times and conditions, and providing input/output data associated with usage, service and support information. 
         [0048]    The broader range of access and control provided by remote computers enables some unique features associated with the APU. For example, a different level of access could be provided to a truck owner (other than the driver) or to a fleet operator, thereby enabling the owner/operator to monitor the truck, the APU  10  and to control both to some degree. The owner/operator could limit the high or low temperatures that could be selected by the driver, or the amount of time the APU is allowed to run, or perform system checks to make sure the APU is not in need of service or maintenance. The owner/operator could similarly limit use of the attached hydraulic pump assembly. Likewise, the owner/operator could set certain controls that could not be overridden by the driver (or only overridden in case of emergency with the proper code), such as when the APU is turned on. For example, some drivers many not want to use the APU, preferring instead to idle the main truck engine, but the owner/operator might want the APU used instead to save money and to cut down on the operating time of the main truck engine. In some fleet trucks, the owner/operator may even prefer to prevent the driver from having any control over the APU through a user interface at all, leaving all such control for preprogrammed operation or remote control by the fleet operator. 
         [0049]    The driver/owner/operator could program the APU to turn on and off at scheduled times, such as turning the APU on for one hour every morning when the truck is not in use. In other cases, the owner/operator could use the programming of the APU to control the driver&#39;s utilization of the APU and associated cabin-area services such as HVAC and electrical power. For example, the owner/operator could set the APU user interface  86  to turn the APU  10  on after the truck has idled for more than five minutes, to see whether the main truck engine is still running, and if necessary to turn off the main truck engine. Providing a wiring connection to the ignition of the truck and the truck&#39;s main battery would readily enable this function. Monitoring the battery would tell the owner/operator whether the main truck engine was still running, thereby enabling the owner/operator to remotely kill and disable the ignition of the truck. 
         [0050]    The control system  86  would also preferably include a real time clock that would enable timed runs of the APU, the current time to be displayed on the display  106 , the APU engine hours to be tracked for maintenance purposes, and for time-stamped logs to be created. The time-stamped logs could be used to log events such as failures, warnings, run time intervals, telemetry, etc. The control system  86  would also preferably include a means of connecting the J1939 bus that is common to most modern tractor/trailer trucks. This bus controls various sub-systems within the truck and could be used by the APU  10  to likewise interface with and control these same systems, such as the running of the main truck engine, the recharging of the battery, etc. As previously noted, the APU  10  could receive power from a battery, such as the main truck engine battery or a separate battery just for the APU  10 . Likewise, a backup battery could be provided within the control system  86  box to keep the ECU and the clock running even when power is lost from the other batteries on the truck. 
         [0051]    As previously noted, remote control of the control system  86  would also enable the owner/operator to perform less nefarious activities, such as monitor oil and coolant levels, monitor hydraulic pump use or performance, perform other diagnostics, perform remote upgrades and maintenance, etc., or to even communicate with the truck driver through the in-truck user interface. Diagnostics provided by the ECU would include various fault codes that correspond to typical engine faults that can either be stored in a log when they occur or remotely transmitted to a central control facility while the truck is on the road. Usage patterns could also be recorded or transmitted to enable fleet operators to facilitate budgeting and planning, or to prevent overuse or abuse. Any of these different levels of control would be associated with different levels of access, such as through a user name and password, such that the driver would have one level of access and control, the operator a second level of access and control, the owner a third level, and the manufacturer or service provider for the APU a fourth level. 
         [0052]    To better explain the temperature control features of the APU, reference is now made to  FIG. 11 , where the cabin HVAC system  84  is explained in detail. The cabin HVAC system  84  is part of the APU  10  and is located within or in close proximity to the cabin of the truck so that it can efficiently transfer hot and cold air into the cabin as required. It is important to note that the APU  10  of the present invention is “passive” to both the main engine of the truck and to the HVAC system associated with that main engine. In other words, the APU  10  (including the HVAC system) does not rely upon any major subsystem or component of the main truck for operation, such as the coolant, refrigerant and oil lines, the HVAC system, the electrical system, etc. The APU  10  can be configured to connect to the truck&#39;s electrical system to provide back-up power and recharge of the truck&#39;s battery or to kill the truck&#39;s engine, but the APU  10  does not rely upon any such connection for its own operation. 
         [0053]    To provide heat to the cabin of the truck, hot water is routed out of the radiator of the APU engine  12  to an electro-mechanical valve  90  within the cabin HVAC system  84  and then to a heater coil  92 . A blower fan, not shown in  FIG. 11 , blows air through the heater coil and into the cabin of the truck to provide heat. Control of heat within the truck is controlled by the valve  90 , which is in turn controlled by the user interface and control system  86 . When a higher temperature is selected by the driver (or remotely) using the control system  86 , the valve  90  is opened further. Likewise, when a lower temperature is desired, the valve  90  may be further closed, or the fan speed could be lowered. 
         [0054]    In extremely cold climates, such as Alaska, parts of the United States, Canada and Europe, an additional heating feature might be required to warm the engine. Inserting an electric heater inside the radiator coolant hose of the APU engine  12  provides this feature. Providing power to the electric heater heats the coolant within the hose and makes it easier for the engine of the APU to start in cold weather. 
         [0055]    The cabin HVAC system  84  provides air conditioning within the cabin of the truck in a similar fashion. The APU engine  12  drives the engine flywheel  26 , which is connected to the air conditioning compressor  28  by the serpentine belt  24 . The air conditioning compressor, which is basically a pump, is responsible for compressing and transferring refrigerant gas to the condenser  34 . The intake or suction side of the compressor  28  draws refrigerant gas from the outlet of the evaporator  94 , further explained below. That refrigerant gas is then compressed and sent to the condenser  34 , where it can transfer the heat that is absorbed from the inside of the vehicle. 
         [0056]    The condenser  34  is like a radiator. It is designed to radiate heat. As previously noted, it can be located in a variety of different locations relative to the APU engine  12  so as to improve air flow through the condenser  34  and to reduce noise from the condenser fan near the cabin of the truck. As hot compressed gasses are introduced into the condenser  34 , they are cooled off. As the gas cools, it condenses and exits the condenser  34  as a high-pressure liquid. This high-pressure liquid is then routed to the receiver-drier  96 , which is designed to separate gas and liquid and to remove moisture and filter out dirt from the refrigerant. The refrigerant is routed from the receiver-drier  96  to the electro-mechanical expansion valve  98 , which can sense both temperature and pressure and can therefore be used to regulate the flow of refrigerant to the evaporator  94 . Hence, to control the air conditioning within the cabin of the truck, the ECU  80  regulates the operation of the compressor  28  and the fan (not shown) through the controls specified by the user interface and control system  86 . 
         [0057]    The evaporator  94  serves as the heat absorption component of the cabin HVAC system  84 . Its primary duty is to remove heat from inside the cabin and to dehumidify the air inside the cabin. As warm air is sucked out of the cabin by the fan (not shown), it travels through the aluminum fins of the cooler evaporator coil, the moisture contained in the air condenses on its surface. And, as refrigerant enters the evaporator and warm air passes through the evaporator fins, the refrigerant boils, causing it to absorb large amounts of heat, which is then carried off with the refrigerant to air conditioning compressor  28 . As the heat is absorbed from the air blowing through the evaporator that air is cooled and in return blown back into the cabin of the truck. 
         [0058]    At the same time that engine flywheel  26  is driving compressor  28  via serpentine belt  24 , engine flywheel  26  is also driving hydraulic pump  210  via hydraulic assembly belt  220 . As described above, the hydraulic pump assembly  201  is a part of the overall APU  10 . Hydraulic pump  210  provides hydraulic pressure to a hydraulic fluid, thereby forcing the hydraulic fluid out through inlet port  215  (not shown in  FIG. 11 ) to hydraulic system  1100 , which as explained above may be a hydraulic lifting system located in the truck&#39;s trailer and used for lifting/moving the goods being shipped, such as automobiles on a car hauler. The hydraulic fluid may return from hydraulic system  1100  and re-enter hydraulic pump  210  via outlet port  215  (not shown in  FIG. 11 ). Alternatively, hydraulic pump  210  may be mechanically coupled to the engine&#39;s crankshaft (not shown in the Figures). For example, hydraulic pump  210  can be driven via a belt functionally attached to a pulley that is itself attached to the crankshaft. 
         [0059]    As previously noted, the ECU  80  is controlled through operation of the user interface and control system  86 .  FIG. 12  illustrates an example of an in-truck user interface  100 . So as to reduce environmental stress and in order to consolidate the location of the various aspects of the control system  86  and the ECU  80 , these two components would be preferably collocated, and referred to herein collectively as the control system  86 , within the cabin of the truck in a chassis of some type. The control system  86  would be contained within a plastic or metal box that would be mounted in a convenient location somewhere within the cabin of the truck, and connected to the APU engine  12 , the cabin HVAC  84 , the hydraulic pump  210 , and the other components of the APU  10  through various wires, although wireless interconnections could also be utilized. The ECU could also be mounted within a separate box somewhere within the cabin and inaccessible to the driver. 
         [0060]    Within either the ECU box or the control system box, would be the microprocessor or controller of the ECU that would interface to the user interface  100 . This user interface would preferably be mounted to the front of one of the boxes within the cabin and be comprised of a series of buttons  102 , a speaker  104  and a display panel  106 . The buttons  102  enable the user to scroll through a series of displayed instructions or results and to make necessary selections. The buttons  102  also enable the user to start and stop the APU engine  12 , select air conditioning or heating, control a fan, turn the temperature in the cabin up or down, turn the hydraulic pump on or off and adjust the hydraulic fluid flow to and from the pump, and access a main menu system on the display  106 . As previously noted, many different types of controls can be utilized in place of buttons, such as dials, knobs, and a wide variety of switches. As shown in  FIG. 10 , the buttons  102  are tact switches that provide a small amount of tactile feedback to the user when operated. Additional feedback could be provided in the form of some tone or audible message to the user to indicate that a button  102  has been fully depressed when making a selection. This tone would be routed through the speaker  104 . 
         [0061]    One of the buttons  102  on the user interface  100  is the start/stop button, which is used to turn the APU engine  12  on and off. When the APU is not running and the start/stop button is selected, the APU engine  12  will be started, and vice versa, when the button is selected when the APU engine  12  is running, then the APU engine will be stopped. However, before the APU engine can be started or stopped through control of the user interface  100 , the ECU needs to be running. Normally, the ECU is booted up when power is provided to the APU system, such as through a battery or through the truck&#39;s electrical system. 
         [0062]    While the present invention has been illustrated and described herein in terms of a preferred embodiment and several alternatives, it is to be understood that the techniques described herein can have a multitude of additional uses and applications. Accordingly, the invention should not be limited to just the particular description and various drawing figures contained in this specification that merely illustrate a preferred embodiment and application of the principles of the invention.