Abstract:
The present invention is directed to an auxiliary power unit for use with a vehicle, typically a truck. The power unit uses an air-cooled generator and associated auxiliary engine to supply power and air regulation requirements to the truck on demand. The air-cooled auxiliary engine is employed with an electrical generator and a compressor to provide the auxiliary power unit. The unit is self-contained in that it is not interconnected with the vehicle liquid coolant systems. A remote control module directs the operation of the power unit to supply heating and air conditioning to the vehicle interior by a sleeper unit. The sleeper unit provides a heating source and a coolant source that are powered by the power unit. A housing for the power unit is designed to assist in cooling and maintenance of the power unit. A series of air inlets are used to direct cooling air from the surrounding air over the generator, engine, and a condenser, so that operating temperatures of the power unit van be maintained within acceptable parameters. The housing also has an access cover that allows the contained power unit to be removed from the housing on a series of guides or channels, thereby facilitating the serviceability of the unit.

Description:
[0001]    The present application claims priority from U.S. Provisional application No. 60/364,633, filed Mar. 18, 2002. 
     
    
     
       FIELD OF THE INVENTION  
         [0002]    The present invention relates to an apparatus and method for providing auxiliary air conditioning, heating, and power to a vehicle.  
         DESCRIPTION OF THE PRIOR ART  
         [0003]    There is a current need for providing auxiliary cooling, heating, and power to a vehicle, such a transport truck. The air temperature control is normally done by an onboard heating system including a heater in both the cab and sleeper cabin of the truck, and by an air conditioning system including an evaporator in both the cab and sleeper. These liquid cooled systems are driven by the truck engine during daytime operation of the truck. In the event of taking a rest or sleep break, the trucker must continue to run the truck engine in order to maintain operation of the air and heat systems in the sleeper cabin. One advantage of this direct heating and cooling system is that no modification to the existing truck infrastructure is needed to operate the air temperature control. However, this direct system is highly inefficient as the truck engine capacity, when idling, is being used solely for air temperature control. It has been found that it is more efficient to use small auxiliary generators to provide power for heating and cooling, rather than rely upon track engine operation when the truck is stationary.  
           [0004]    Accordingly, cross-country truckers prefer to control the temperature of the ambient air in the sleeper cabin using auxiliary power units, which are connected to the main air treatment systems of the truck. In regions where cold weather is encountered, the engine is often idled when the vehicle is parked in order to keep the truck&#39;s motor oil, diesel fuel, and engine warm so that it will restart. Therefore, it is known to use liquid cooled auxiliary generator/engine systems to keep a turned off truck engine warm by interconnecting, through a complicated series of check valves, the auxiliary liquid coolant lines of the auxiliary engine with the standard coolant lines of the truck engine. The check valve system is used to prevent damage to the auxiliary and truck engine cooling systems in the event they are run simultaneously. One advantage of this system is that a more efficient use of auxiliary engine power is employed to control the air temperature of the cabin while the truck engine is turned off, as well as to keep the truck engine and related components warn with the heat by-products produced by the auxiliary engine. However, the disadvantage is that this system of interconnected liquid coolant lines to distribute the heat by-products may void the warranty of the truck, due to the extensive retrofit that is required to install the interconnections. Further, this system is more costly to maintain due to the greater complexity present in the valving architecture. Another problem with this system is that the operation of the auxiliary engine may be inhibited in the event of a breakdown in the truck coolant lines and associated components, due to the required cooperation between the truck and auxiliary coolant lines.  
           [0005]    Another auxiliary liquid cooled power unit is described by U.S. Pat. No. 5,333,678 by Mellum et al. This patent involves auxiliary refrigerant lines that are separate and distinct from the vehicle&#39;s refrigerant lines, which allows the vehicle&#39;s compressor and the auxiliary compressor to ran simultaneously. Further, the auxiliary liquid coolant lines and the vehicle coolant lines are interconnected, which still allows for the unit to provide heat when the vehicle engine is running or not. However, this system still has some of the above mentioned inherent problems due to the retrofit that is required, as well as maintenance issues due to the complexity of the interconnections.  
           [0006]    Therefore, all of the above described auxiliary power units are liquid cooled units that involve complex interconnections between the vehicle engine and the auxiliary engine. It is desirable to supply power and air temperature control to a vehicle, while minimising the use of extensive retrofits of the original truck infrastructure.  
           [0007]    A further problem common to most current auxiliary power units is serviceability. Even if the units each have a completely removeable cover, the units are often mounted snugly between the truck fuel tank and the front side of the rear wheel under the sleeper cabin. This configuration can prevent several items on the power unit from being serviced, without removing the complete unit from the truck. This can be very time consuming and also costly if the air conditioning system (A.C.) has to be drained and then recharged on re-assembly.  
           [0008]    Other problems typically encountered with current auxiliary power units is that they use belt driven A.C. compressors, or they are completely self-contained roof mounted A.C. units. The belt driven A.C. compressors require an electric clutch in the A.C. sheave to turn it on and off, which adds another maintenance item along with the belt. The roof mounted A.C. units are not compatible with current design truck sleeper cabins as the truck roof is not flat, which is required for a roof mount A.C.  
           [0009]    It is an object of the present invention to provide an auxiliary power unit to obviate or at least mitigate some of the above-presented disadvantages.  
         SUMMARY OF THE INVENTION  
         [0010]    Current auxiliary power units are liquid cooled units that involve complex interconnections between die vehicle engine and the auxiliary engine. It is desirable to supply power and air temperature control to a vehicle, while minimising the use of extensive retrofits of the original truck infrastructure. According to the present invention, an air-cooled auxiliary engine is employed with an electrical generator and a compressor to provide an auxiliary power unit. The unit is self-contained in that it is not interconnected with the vehicle liquid coolant systems. A remote control module directs the operation of the power unit to supply heating and air conditioning to the vehicle interior by a sleeper unit. The sleeper unit provides a heating source and a coolant source that are powered by the power unit.  
           [0011]    The present invention also provides a housing for the power unit that assists in cooling and maintenance. A series of air inlets are used to direct cooling air from the surrounding air over the generator, engine, and a condenser, so that operating temperatures of the power unit van be maintained within acceptable parameters. The housing also has an access cover that allows the contained power unit to be removed from the housing on a series of guides or channels, thereby facilitating the serviceability of the unit. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]    These and other features of the preferred embodiments of the invention will become more apparent in the following detailed description in which reference is made to the appended drawings wherein:  
         [0013]    [0013]FIG. 1 is a side view of a vehicle with a mounted auxiliary power unit;  
         [0014]    [0014]FIG. 2 is a block diagram of the power unit of FIG. 1;  
         [0015]    [0015]FIG. 3 is a remote control module for the power unit of FIG. 2;  
         [0016]    [0016]FIG. 4 is a diagram of the cooling system for the power unit of FIG. 2; and  
         [0017]    [0017]FIG. 5 is a side view of a housing for the power unit of FIG. 1; and  
         [0018]    [0018]FIG. 6 is a second embodiment of the control module of FIG. 3. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0019]    Referring to FIG. 1, an auxiliary power unit  8  for providing air temperature control and power to a vehicle  10  is contained within a housing  20 , which is connected to a rail  18 . Combustable fuel requirements for the power unit  8  are supplied through a fuel line  22 , which is connected to a fuel tank  16  mounted on the vehicle  10 . Liquid refrigerant lines  24  and an electrical power line  26  are connected from the power unit  8  to a sleeper unit  44  (see FIG. 2), mounted within a sleeper cabin  14  of the vehicle  10 . The sleeper unit  44  is used to provide for both the cooling and heating requirements of the ambient air within the vehicle interior  12 . A user of the vehicle  10  controls the sleeper unit  44  by a programmable control module  46  (see FIG. 2) also mounted within the interior  12  of the vehicle  10 . It should be noted that the power unit  8  also has a power cord  28  (see FIG. 2) that is connected to the vehicle battery  30 , in order to supply start-up power to the unit  8  when activated by the control module  46 .  
         [0020]    Referring to FIG. 2, the power unit  8  includes a generator  32  that supplies electrical power at 2 voltages, 110VAC and 220VAC at 60 Hz and 5.4 kW, which are then used directly or converted to 12 VDC as required. The generator  32  can be such as but not limited to a Markon model BL105D. An air-cooled diesel engine  34  is connected to the generator  32  through a shaft  36 , and uses fuel from the fuel tank  16  supplied by the fuel line  22 . The engine  34  can be such as but not limited to a Kubota Model OC95-5 diesel with 9.5 Hp at 3600 RPM. The power unit  8  also has a 220 VAC-3 Hp hermetically sealed air conditioning compressor  38 , which is powered by a 220 VAC power line  40  connected to the generator  32 . The compressor  38  can be such as but not limited to a Danfoss model MTZ36 JG. The power unit  8  also contains an air conditioning condenser  42  that is operatively coupled to the compressor  38  through refrigerant lines (not shown).  
         [0021]    The power unit  8  is connected to the sleeper unit  44  by the liquid refrigerant lines  24  and the electrical power line  26 . The sleeper unit  44  is located within the sleeper cabin  14  to provide air temperature control of the ambient air temperature therein. The sleeper unit  32  has a cabin evaporator  48  run off of the liquid refrigerant, which is supplied by the compressor  38  and then returned thereto through the refrigerant lines  24 . The evaporator  48  is used to regulate the air conditioning of the cabin  14 . The sleeper unit  44  also has a 110 VAC electric heater  50  to provide for heating requirements of the cabin  14 . The heater  50  is powered by the electrical line  26 , which is supplied by the generator  32 . A fan  48  is also included in the sleeper unit  44  to circulate the air within the cabin  14  past the evaporator  46  or the heater  50 , so as to help increase the efficiency of the air temperature regulation.  
         [0022]    Operation of the sleeper unit  44  and the power unit  8  is controlled by the control module  46 , which is accessible within the cabin interior  12  by the user of the vehicle  10 . The module  46  monitors the operation of the power unit  8  through control line  47 , and the sleeper unit  44  through control lines  49 ,  51 ,  53 . Referring to FIG. 3, the module  46  can be such as but not limited to a solid state programmable control module. The module  46  has an engine control button  56 , which can be employed by the user to manually start and stop the auxiliary engine  32  remotely from within the cabin  14 . The module  46  can also have an engine pre-heat indicator  54 , which indicates to the user that the engine  34  is being pre-heated before starting in cold weather conditions. The module  46  also has a fan control  64  for controlling the speed of the fan  52 , such as but not limited to low, medium, and high. The module  46  also has a temperature control  66 , which can be used to regulate the output of the evaporator  48  or the heater  50 . A type selector  68  is provided to select between the evaporator  48  or the heater  50  for temperature regulation.  
         [0023]    The module  46  also has indicators  58  and  60 , which signal to the user that the auxiliary engine  34  is experiencing high temperatures and/or low oil pressures respectively. These indicators  58 ,  60  are connected by line  47  to sensors located on the engine  34 , as is known in the art, which monitors for temperature and pressure alarm conditions. The module  46  also has a safety shut-down switch  62 , which is triggered when the engine  34  operation encounters alarm condition(s). Accordingly, the module  46  also has a fully automatic mode that turns the power unit  8  on and off as required, which could be due to such as but not limited to low truck engine temperatures, low battery  30  voltage, and the cabin  14  temperature lower or higher than the temperature set by the temperature control  66 .  
         [0024]    Referring to FIG. 4, the power unit  8  is contained within the housing  20 , which protects the components of the power unit  8  from adverse weather conditions and guides the cooling air for the engine  34  through selected ducts to optimise cooling. The housing  20  is sealed from outside air entering the interior  70 , except through an air inlet  72  for the combustion air used by the engine  34  through an air filter  73 , a perforated air inlet  74  for directing cooling air over the air conditioning condenser  42  and over cooling fins  83  for cooling the engine  34 , and a cooling air inlet  76  for suppying cooling air to the generator  32 . The housing  20  also has a cooling air outlet  78  to direct the used cooling air from the generator  32  and the engine  34 , as well as to exhaust the engine  34  combustion gases. It should also be noted that the housing  20  is divided into two regions  70  and  71  by a scaled baffle plate  80 . The baffle plate  80  only allows combustion air into the engine intake  72  through the air filter  73 , and the cooling air for the engine  34  through a cooling air intake  82 . A cooling fan  84  draws the engine cooling air first through the perforated air inlet  74  and past the air conditioning condenser  42 . This configuration provides for cooling of the condenser  42  without the need for a separate flow path and fan for the condenser  42 . It should be noted that the condenser  42  was oversized for cooling of the refrigerant processed from the compressor  38 , so as to help keep the air temperature rise across the condenser  42  within limits for subsequent use of the air from the inlet  74 , as the air is then drawn into the inlet  82  by the fan  84  for use as engine cooling air over the fins  83 .  
         [0025]    In operation of the power unit  8 , the engine  34  is first turned on by pressing the engine control button  56  into the on position. The engine  34  then begins a preheat function, as indicated by the preheat indicator  54  on the module  46 , by drawing power through the line  28  from the battery  30 . Once the engine  34  reaches a starting temperature, the battery  30  is used to supply the starting current required to start the engine  34 . It should be noted that the battery  30  no longer supplies power once the engine  34  has started. The engine  34  then turns the generator  32  by the shaft  36 , in order to generate the power required to supply the operation of the compressor  38  through line  40 , the heater  50  and fall  44  through line  26 , and the cooling fan  84 . It should be noted that interruption of the generated power through line  40  is accomplished by the control module  46  connected to the compressor  38  by line  41 .  
         [0026]    Accordingly, the cooling fan  84  then draws cooling air through the inlet  74  and over the condenser  42  for cooling any heated refrigerant supplied by the compressor  38 . This somewhat heated cooling air is then further drawn into the inlet  82  and then passed over the fins  83  to cool the engine  34 . Similarly, the generator  32  directs cooling air through the inlet  76  for cooling. The used cooling air for the engine  34 , generator  32 , and the combustion gasses are then exhausted out of the air outlet  78 . Further, the combustion inlet  72  directs combustion air through the air cleaner  73  and through the baffle plate  80  and into the engine  34 .  
         [0027]    When desired, the user then selects the air temperature on the module  46  by the temperature control  66 , selects the speed of the fan  44  by the speed control selector  64 , and selects either the use of the heater  50  or the evaporator  48  by the switch  68  to enable the air temperature regulation of the ambient air in the cabin  14  interior. The module  46  then regulates the operation of the selected heater  50  or evaporator  48  by turning on or off the power unit  8 , as needed, so that the air temperature in the cabin  14  remains within acceptable boundaries as selected by the temperature control  66 .  
         [0028]    As described above, the power unit  8  is enclosed within the housing  20  so as to protect the unit  8  components from adverse weather, and to direct the cooling air so as to optimise cooling. However, this configuration is typically less than optimal when maintenance is required on failed or worn out components of the power unit  8 . This limited ease of serviceability for the unit  8  is also farther restricted due to the positioning of the housing  20  on the rail  18 .  
         [0029]    Referring to FIG. 5, a side  86  of the housing  20  has been removed for clarity. The power unit  8  is attached to a mounting frame  88 , which can move along a pair of channels  90  by wheels  92 . The wheels  92  are located on either side of the frame  88 . The channels  90  are located on either side of the housing  20  and are fixed to the bottom  93  of the housing  20 . The enclosure  20  also has a front cover  94  that opens approximately 90° between an open position indicated as arrow  95  and a closed position indicated as arrow  96 . The cover  94  is hinged at a pivot point  98  at one end and can be releasably secured at the other end in the closed position  96  by a lock  100 . A suspension cable  102  holds the cover  94  in the open position  95  so that the surface  104  of the cover  94  is in a plane substantially the same as an inside surface  106  of the bottom of the housing  20 . Accordingly, the cover  94  has side flaps  108  that perform as extensions of the channels  90  when the cover  94  is placed in the open position  95 .  
         [0030]    Therefore, when maintenance is desired on the power unit  8 , the front cover  94  is unlocked by releasing the lock  100  and the cover  94  is moved from the closed position  96  to the open position  95 . The flaps  108  act as extensions of the channels  90 , so that the complete power unit  8  situated on the frame  88  can be rolled on the wheels  92  out of the housing  20  and onto the surface  104  of the cover  94 . Accordingly, this removal procedure brings the power unit  8  away from the vicinity of the fuel tank  16 , the truck wheels 17 , and sleeper cabin  14  for servicing. It should be noted that the connections  22 ,  24 ,  26 ,  28 ,  41 , and  47  to the power unit  8  are done by a flexible connector  97 , which allows for movement of the power unit  8  without disassembly or damage to the connections  22 ,  24 ,  26 ,  28 ,  41 , and  47 . Once the servicing is complete, the power unit  8  can be rolled back into the housing  20 , locked into position if desired by a lock (not shown), and then the cover  94  can be returned to the closed position  96  and secured by the lock  100 . It is recognised that fixed mounted units  8  within the housing  20  can be used for those installations of the power unit  8  where enough space is available for servicing.  
         [0031]    The flexible connector  97  can be such as but not limited to a GUS E-Z energy chain, which provides for bundling and containment of the connections  22 ,  24 ,  26 ,  28 ,  41  and  47  within the chain. The flexible connector  97  provides for linear strain relief, and to help support the connections  22 ,  24 ,  26 ,  28 ,  41 , and  47  to permit torsional movements as well.  
         [0032]    Further, the power unit  8  foot print can be rectangular so that the housing  20  and power unit  8  can be mounted on either of 2 sides—a long side or a short side on the rail  18 . The power unit  8  mounting frame  88  in turn could be designed to mount the wheels  92  on all four sides of the frame  88 , so it can be assembled to roll length-wise or cross-wise out of the housing  20 . Different housings  20  are available with the either a side opening or an end opening cover  94 .  
         [0033]    Although the invention has been described with reference to certain specific embodiments, various modifications thereof will be apparent to those skilled in the art without departing from the spirit and scope of the invention as outlined in the claims appended hereto.