Abstract:
An auxiliary power system for a motor vehicle comprising a first engine having an accessory belt drive system comprising a belt and at least one driven pulley, the belt drivable by a driver pulley, the accessory belt drive system further comprising a motive member for driving the accessory belt drive system, the motive member comprises a motor engaged with the accessory belt drive system, a second engine operable to drive an electric power source, the electric power source electrically connected to the motive member, an alternate power source other than the electric power source connected to the motive member, a switch for selecting between the electric power source and the alternate power source, and the motive member, drivable by the electric power source or the alternate power source in order to drive the accessory belt drive system when the first engine is not operating.

Description:
REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application is a continuation-in-part of and claims priority from U.S. non-provisional application Ser. No. 11/301,310 filed Dec. 12, 2005. 
     
    
     FIELD OF THE INVENTION  
       [0002]     The invention relates to an auxiliary power system for a motor vehicle, namely, an auxiliary power system comprising an accessory belt drive system having a motive member for driving the accessory belt drive system, the motive member comprising an electric motor connectable to at least two alternate electric power sources.  
       BACKGROUND OF THE INVENTION  
       [0003]     Almost two million long-haul trucks deliver various goods throughout the United States each year. The great majority of long haul trucks utilize some form of diesel engine. It is not uncommon for long-haul trucks to be driven 150,000 miles annually.  
         [0004]     During trips as well as during loading and unloading operations truck engines are operated at idle for an average of 1900 hours. Idling large diesel engines is necessary to provide power needed to operate the truck equipment, power lights, appliances, communication gear, and air conditioning or heating for the cab and sleeping area when drivers are resting. Idling the engines for heavy trucks can cost about $2.50/hr in fuel, about $0.09/hr in preventative maintenance, and about $0.09/hr in overhaul costs at current fuel and maintenance rates.  
         [0005]     While idling an engine provides the power needed to maintain a comfortable environment for the driver it has unwanted consequences. Operating a high horsepower diesel engine at low RPM under light load results in the incomplete combustion of fuel and gives off undesirable exhaust emissions. In addition, operating the diesel engine at low speed causes twice the wear of internal parts compared with the road speed RPM.  
         [0006]     Auxiliary power units (APU&#39;s) are known which provide power while significantly reducing the need to idle the primary engine. The incentives for using APU&#39;s include reduced fuel use and engine wear, prolonged engine life and cuts in maintenance costs, and elimination of approximately 70%-90% of diesel emissions during long periods of engine idling.  
         [0007]     Auxiliary power units are portable, truck mounted systems that can provide climate control and power for trucks without the need to operate the primary diesel engine at idle. Prior art systems generally consist of a small internal combustion engine (usually diesel) equipped with a variety of accessories.  
         [0008]     The APU diesel engine uses the same coolant and coolant system as the primary diesel engine. During stops when the primary diesel is turned off the APU diesel circulates the coolant to the primary diesel to keep it warm during winter months for easy starts. The same coolant is also routed to the heater core inside the cabin to provide heat to the drive. The APU alternator can provide power for the interior lights, marker lights, and recharging the battery. An inverter can convert the alternator DC current to 110V AC power for televisions and microwaves. The APU air conditioner compressor uses the primary engine installed refrigerant, expansion valve, evaporator, and blower to provide chilled and dehumidified air to the cabin. The APU has its own condenser to reject the heat from the refrigerant.  
         [0009]     As an example, APU&#39;s are known which comprise a two cylinder diesel engine driving a generator and an alternator. The generator provides power to a 110 v HVAC system (separate from the factory installed air conditioning system) and electrical receptacles for microwaves, TVs, etc. The alternator is used to charge the batteries and run marker lights. In some instances, the small diesel engine drives a water pump that circulates coolant to the large diesel engine to keep it warm for starting during the winter months.  
         [0010]     Another known APU comprises a small diesel engine which drives a generator. The generator provides power for electrically driven accessories such as the air conditioning compressor and the water pump. Since the accessories are driven by electrical motors and are powered by the APU, the primary diesel engine can be off. The speed of each accessory can be individually controlled and, therefore, provide only the conditioned air or such other power needed at that moment. The accessories are not forced to rotate at some fixed speed ratio of the engine speed.  
         [0011]     Representative of the art is U.S. Pat. No. 6,048,288 (2000) to Tsujii et al. which discloses an engine wherein auxiliary machines are operated by a motor generator where the engine is stopped to reduce electric power consumption.  
         [0012]     Reference is made to copending U.S. non-provisional application Ser. No. 10/991,548 filed Nov. 18, 2004.  
         [0013]     What is needed is an auxiliary power system comprising an accessory belt drive system having a motive member for driving the accessory belt drive system, the motive member comprising an electric motor connectable to at least two alternate electric power sources. The present invention meets this need.  
       SUMMARY OF THE INVENTION  
       [0014]     The primary aspect of the invention is to provide an auxiliary power system comprising an accessory belt drive system having a motive member for driving the accessory belt drive system, the motive member comprising an electric motor connectable to at least two alternate electric power sources.  
         [0015]     Other aspects of the invention will be pointed out or made obvious by the following description of the invention and the accompanying drawings.  
         [0016]     The invention comprises an auxiliary power system for a motor vehicle comprising a first engine having an accessory belt drive system comprising a belt and at least one driven pulley, the belt drivable by a driver pulley, the accessory belt drive system further comprising a motive member for driving the accessory belt drive system, the motive member comprises a motor engaged with the accessory belt drive system, a second engine operable to drive an electric power source, the electric power source electrically connected to the motive member, an alternate power source other than the electric power source connected to the motive member, a switch for selecting between the electric power source and the alternate power source, and the motive member drivable by the electric power source or the alternate power source in order to drive the accessory belt drive system when the first engine is not operating. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0017]     The accompanying drawings, which are incorporated in and form a part of the specification, illustrate preferred embodiments of the present invention, and together with a description, serve to explain the principles of the invention.  
         [0018]      FIG. 1  is a schematic view of the inventive system.  
         [0019]      FIG. 2  is a chart of available power versus power needed by a truck.  
         [0020]      FIG. 3  is an alternate embodiment of the inventive system.  
         [0021]      FIG. 4  is an alternate embodiment of the inventive system.  
         [0022]      FIG. 5  is an alternate embodiment of the inventive system.  
         [0023]      FIG. 5A  is a detail of the pulley arrangement for the embodiment in  FIG. 5 .  
         [0024]      FIG. 6  is an alternate embodiment of the inventive system.  
         [0025]      FIG. 6A  is a detail of the pulley arrangement for the embodiment in  FIG. 6 .  
         [0026]      FIG. 7  is an alternate embodiment of the embodiment in  FIG. 6 .  
         [0027]      FIG. 8  is an alternate embodiment using a fuel cell. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0028]      FIG. 1  is a schematic view of the inventive system. An auxiliary internal combustion (IC) engine  10  is used to propel an electric generator  20  such as an AC single phase or three phase generator or a DC generator. A belt  11  transmits the power from engine  10  to generator  20 . Engine  10  may comprise either a diesel engine or gasoline engine or any other suitable engine known in the art. The electrical energy produced by generator  20  is used to power AC electrical loads  30  and an AC electric motor  40  via suitable known power management devices such as an inverter/controller unit  85 . The power management device is used to convert power generated in one form and voltage level into other forms and voltage levels.  
         [0029]     AC electric motor  40  is incorporated within the asynchronous belt drive system (ABDS) of a main engine  50 . The main engine comprises any engine used on over the road tractor trailers rigs, or any other vehicle utilizing a large main diesel engine such as busses, freight trucks and the like.  
         [0030]     The ABDS system is the belt driven system that is used to drive various engine and vehicle accessories. It can include various accessories such as an air conditioner compressor  43 , alternator  44 , AC motor pulley  45 , and crankshaft pulley  51 . A belt  41  trained among the accessories engages a pulley attached to each as is known in the art. A tensioner  42  known in the art is used to maintain proper tension in belt  41 .  
         [0031]     During periods when the main engine  50  is not operating but accessory systems are still needed, electric motor  40  becomes the prime mover for the ABDS. An electromagnetic clutch  52  (or in the alternative a one way clutch) is attached to the crankshaft  51 , or power-take-off (PTO), of the main engine  50 . Electromagnetic clutch  52  is known in the art, for example, Ogura Industrial Corp. model no. 515376.  
         [0032]     Clutch  52  enables the AC electric motor  40  to drive the accessories without operating main engine  50  or turning the main engine crankshaft. Alternator  44  provides DC electrical power to recharge the batteries  61  and drive DC electrical loads  60  such as emergency flashers, marker lights, cab lights, radios, fans, and so on. Operation of the air conditioner (AC) compressor  43  makes it possible to deliver cool conditioned air to the truck&#39;s cab when the truck main engine is idle. A one way clutch  45   a  within pulley  45  disengages the motor  40  shaft when the main engine  50  is operating.  
         [0033]     The inventive system is also capable of utilizing shore power  70  at highway rest facilities. Shore power  70  is electrical power (and may sometimes include internet, telephone, and cable connections) made available to vehicles at truck stops. A proposed standard for shore power (currently called the National Truck Stop Electrification Standard) is 240 VAC at 30 amps (See  FIG. 2 ). However, the inventive system can also be configured to operate at 120 VAC and 208 VAC as well.  
         [0034]      FIG. 2  is a chart of available power versus power needed by a truck. The power generation capability of the inventive APU is shown as approximately 5 kW. The next three columns depict different amounts of shore power, namely 240 VAC/30 Amp, 120 VAC/30 Amp, 120 VAC/15 Amp. Lastly, an example column is shown for cab electrical needs. As shown, these can include a battery charging load, blower, condenser, AC compressor or heating needs. The APU can be sized according to the electrical needs of the cab.  
         [0035]     Referring to  FIG. 1 , if shore power  70  is available, there will be no need to operate engine  10 . The power for the AC motor  40  is then provided through the electrical shore power connection  70 . A switch  80  is used to select the source of power—either from generator  20  or shore power  70 . Inverter/converter  85  in  FIG. 1  accommodates the variety of shore power amounts and qualities, thereby allowing use of the full variety of shore power sources for the truck cab needs.  
         [0036]     An alternate embodiment of the proposed invention in  FIG. 1  is to remove alternator  44  and AC motor  40  and replace alternator  44  with an AC/DC inverter  91  and the AC motor  40  with a motor/generator  90  as depicted in  FIG. 3 . Motor/generator  90  is capable of absorbing power, can operate as a motor, or operate as a generator for generating power. Motor/generator  90  is similar to the motor/generators used on mild hybrid vehicles, for example the Toyota Crown™ or PSA C3™.  
         [0037]     AC/DC inverter  91  converts AC power from the motor/generator  90  to DC power when the motor/generator  90  is in generator mode, and thereby providing power to DC loads  60  and battery  61 .  
         [0038]     When used in the motor mode to drive belt  41 , motor/generator  90  is driven by either the shore power  70  or generator  20  via intervening power management device  85 .  
         [0039]     Within the main diesel engine belt drive system, the placement of motor/generator  90  also determines the positions of the tensioner  42  and  46  as well as the desired belt tensions. The ability of motor/generator  90  to provide and absorb power requires use of at least two tensioners for the tensioning system, one on each side of the motor/generator  90  since depending upon the operating mode (motor or generator) the belt loads will be reversed.  
         [0040]     Yet another alternate embodiment of the system described in  FIG. 1  involves providing DC power, not from the alternator  44 , but instead from the generator  20  via an AC/DC converter  100  as shown in  FIG. 4 . Although alternator  44  remains in the main engine belt drive system it does not generate DC power. This is accomplished by removing the alternator rotor winding current. AC motor  40  is only used to propel AC compressor  43 . Motor  40  is driven by either the shore power  70  or AC generator  20  via power management device  85  when motor  40  is used in the motor mode. The size and power requirements of AC motor  40  shown in  FIG. 1  can be reduced in this alternate embodiment. For example, the rating of motor  40  in  FIG. 1  is 20 Nm@3000 RPM and the rating in  FIG. 4  is 10 Nm @3000 RPM. As described in  FIG. 1 , a one way clutch  45   a  disengages the motor  40  shaft when the main engine  50  is running.  
         [0041]     In yet another alternate embodiment, the inventive system involves providing DC power to DC loads  60  and for battery  61  charging when the main engine  50  is not operating. DC power is not obtained from the alternator  44 , but from a DC generator  21  via switch  80  through a DC to DC converter  1001  as shown in  FIG. 5 .  
         [0042]     DC generator  21  may be of any appropriate capacity, however, the capacity selected for this embodiment is approximately 6 kW.  
         [0043]     Although alternator  44  is included in the belt drive system it will not generate DC power when engine  10  is operating and main engine  50  is not operating. Tensioner  52 , known in the art, maintains proper operating tension in belt  41 .  
         [0044]     Power from DC generator  21  transmitted to DC motor  47  is used to propel AC compressor  43  through belt  48  when main engine  50  is not operating. If the power produced by generator  21  is sufficiently compatible that it can be consumed by DC motor  47 , then no intervening power management devices are required. The generator and motor are electrically directly connected to each other. In this embodiment the speed of DC motor  47  will be relatively low, approximately 2000-3000 RPM.  
         [0045]     Clutch  43   b  allows the AC compressor  43  to be disconnected from the main engine belt system when the main engine is not running.  
         [0046]     When shore power  70  is available, switch  80  routes power to the AC/DC inverter  1000 . DC output power from inverter  1000  drives DC motor  47 , as well as provides energy for the battery  61  and the DC loads  60  through DC/DC converter  1001 .  
         [0047]      FIG. 5   a  is a detail of the pulley arrangement for the embodiment in  FIG. 5 . Pulley  44   a  of alternator  44  will not rotate when engine  50  is not operating because the main engine belt  41  will not be propelled by the DC motor  47 . DC motor  47  through one way clutch  49   b  and pulley  49   a  will propel belt  48  and thereby AC compressor  43  through pulley  43   c,  which is directly attached to the armature  43   d  of AC compressor  43 . When engine  50  is not operating electromagnetic clutch  43   b  is disengaged to prevent belt  41  of the main engine belt drive system from rotating. For example, when AC compressor pressures are high, DC motor  47  will be shut off to simply stop rotating the AC compressor armature through pulley  43   c  to thereby relieve the excess pressure.  
         [0048]     When main engine  50  is operating, belt  41  will propel alternator  44  and AC compressor pulley  43   a.  When the AC compressor shaft is to be rotated, electromagnetic clutch  43   b  is engaged and thereby the electromagnetic clutch armature  43   d  which is attached to the AC compressor shaft will be engaged with and rotated with pulley  43   a.  Although pulley  43   c  will also rotate and propel belt  48  and pulley  49   a,  the DC motor  47  shaft will be disengaged and will not rotate because of the decoupling action of the one way clutch  49   b.    
         [0049]     Electromagnetic clutch  43   b  is known in the art, for example, an Ogura Industrial Corp. model 52184900.  
         [0050]     Also, in this alternate embodiment no clutch is needed at crankshaft  51  of the main engine  50 , which makes integration of the system to existing vehicles universal. Namely, any existing or new belt drive system layout is a suitable candidate for use of this system since the interconnection on the main engine  50  requires only installation of the DC motor  47 , clutches/pulleys and belt  48  at the AC compressor  43 .  
         [0051]     Yet another alternate embodiment of the proposed system is shown in  FIG. 6  which comprises omitting the alternator  44  from the system shown in  FIG. 5 . Alternator  44  is omitted and replaced by a high voltage motor/generator  92 .  
         [0052]     When main engine  50  is running, AC compressor  43  is driven by belt  41  through a pulley  43   d  attached to electromagnetic clutch  43   b.  AC compressor  43  rotates when electromagnetic clutch  43   b  is engaged. Electromagnetic clutch  93   c  is declutched when main engine  50  is running to prevent driving belt  410 . However, when main engine  50  is operating motor/generator  92  is operated in generator mode to provide power for the battery and DC loads  60 .  
         [0053]     When engine  10  is running or shore power  70  is available and the main engine  50  is not running, the power coming from the AC/DC inverter  1000  (shore power connected) or the DC/DC converter  1001  (DC generator  21  operating) provides the energy for the DC motor/generator  92  which then functions as a motor to drive belt  410 . Belt  410  is driven by pulley  93   d.  DC motor/generator  92  then propels the AC compressor  43  armature/shaft through engaged electromagnetic clutch  93   c,  through belt  410  and pulley  43   a.  One way clutch  93   b  will be over-running and belt  41  will not rotate. In this embodiment no one-way clutch as described in  FIG. 1  is needed on the crankshaft  51 .  
         [0054]      FIG. 6A  is a detail of the pulley arrangement on motor/generator  92  and AC compressor  43 . Disposed on motor/generator  92  is pulley  93   a  and one-way clutch  93   b  on the belt  41  side, and pulley  93   d  and electromagnetic clutch  93   c  on the belt  410  side. Also disposed on AC compressor  43  is electromagnetic clutch  43   b  and pulley  43   d  on the belt  41  side, and pulley  43   a  on the belt  410  side directly connected to the armature of AC compressor  43 . Electromagnetic clutches  93   c  and  43   b  are known in the art, including for example, Ogura Industrial Corp. model no. 522860.  
         [0055]     When the main engine  50  is not operating motor generator  92  is operated as a motor, and electromagnetic clutch  93   c  is engaged, thereby driving belt  410 . Belt  410  propels Ac compressor  43  through pulley  43   a.  One way clutch  93   b  prevents belt  41  from being driven.  
         [0056]     When the main engine  50  is running, crankshaft  51  is the prime mover through belt  41 . Crankshaft  51  propels the DC motor/generator  92  through belt  41 , pulley  93   a  and one-way clutch  93   b  whereby DC motor/generator  92  functions as a generator. In this embodiment, motor/generator  92  can rotate at much higher speeds, for example approximately 11000 RPM, than the embodiment in  FIG. 5  and must be designed for these conditions. In an alternate arrangement, the diameters of pulley  93   a  and  93   d  can be adjusted to limit speed.  
         [0057]      FIG. 7  is an alternate embodiment of the embodiment in  FIG. 6 . The embodiment in  FIG. 7  is as described for  FIG. 6  with the following exceptions. In this embodiment, battery pack  100  is used in place of the engine  10  and DC generator  21 . The batteries used in battery pack  100  are known in the art.  
         [0058]     Battery pack  100  is used to supply power to the system when main engine  50  is not operating, i.e., to the DC loads  60  and DC motor/generator  92 . Power from battery pack  100  is managed by the power management hardware/software  101  (known in the art) by which the system supplies energy at appropriate voltage levels to DC motor  92  which then propels AC compressor  43  as described elsewhere in this specification for  FIG. 6 . The power management hardware/software also provides energy to the DC loads  60  from the battery pack  100 .  
         [0059]     No battery  61  charging will take place while the system is being operated with the battery pack  100 . In this case battery  61  is electrically disconnected by switch  102 . Battery pack  100  is recharged only when the main diesel engine  50  is operating. When engine  50  is operating switch  102  closes and DC motor/generator  92  operates as a generator to charge battery pack  100 , provide energy to the DC loads  60 , and recharge the main truck batteries  61 .  
         [0060]     Yet another embodiment comprises use of a fuel cell in lieu of batteries.  FIG. 8  is an alternate embodiment using a fuel cell. Fuel cells  220  are connected to switch  80 . The APU system is otherwise described in  FIG. 7 .  
         [0061]     There are several types of fuel cells available. These include but are not limited to phosphoric acid, alkali, and proton exchange membrane (PEM). An example of a PEM fuel cell is the Nextra™ fuel cell from Ballard Power Systems, Inc. For example, assuming a fuel cell power capacity of ˜1.5 kW, then two fuel cell units arranged in parallel will be required to supply enough power for the APU electrical and air conditioning requirements. Of course, any number of fuel cells may be included in the system depending upon the power requirements.  
         [0062]     Fuel cells can operate with approximately 45% efficiency and can use either methanol or gaseous hydrogen as fuel. Because of the toxicity of methanol and water solubility, hydrogen is preferred. Hydrogen is plentiful and can be used directly by the fuel cell (no on board reforming is necessary). For example, approximately 6.8 Kg of compressed hydrogen is required to support the APU for five days assuming operating eight hours/day.  
         [0063]     The output voltage of the fuel cell is variable dependent on the current load. Open circuit output voltage can be approximately 42V while at full current draw the voltage can drop to approximately 25V. A power management system is required to condition the variable 25-42V output voltage level to an appropriate voltage and amperage useable by the electric motor driving the AC compressor and the 12 V DC loads.  
         [0064]     In some instances, motor  92  at start up can have a high initial temporary current draw. If the fuel cell has to produce power sufficient to meet this temporary peak power demand, its power producing capability would have to be much greater, and hence the fuel cell unit would be larger and more expensive. By using a load leveling battery  221  during peak power draws for example during motor starts, the battery then temporarily augments the fuel cell power output. Load leveling battery  221  is connected to the power management unit  101 . Use of the load leveling battery  221  in conjunction with the power management unit  101  enables the fuel cells  220  to be reasonably sized based upon a levelized load, for example 3 kw.  
         [0065]     Although forms of the invention have been described herein, it will be obvious to those skilled in the art that variations may be made in the construction and relation of parts without departing from the spirit and scope of the invention described herein.