Patent Publication Number: US-2006000228-A1

Title: Auxiliary air-conditioning apparatuses and methods for vehicles

Description:
BACKGROUND OF THE INVENTION  
      This invention relates to air-conditioning apparatuses and methods and, in particular, to air-conditioning apparatuses and methods for vehicles having auxiliary power units.  
      Larger vehicles, for example large diesel tractors used for pulling large trailers on highways, are frequently provided with auxiliary power units. These units, which include an auxiliary diesel engine, much smaller than the vehicle engine, and an electrical generating unit, are utilized to provide auxiliary power when the vehicle engine is shut off. The use of such auxiliary power units reduces fuel wastage as well as vehicle emissions.  
      One highly desirable characteristic of auxiliary power units is the ability to operate an auxiliary air-conditioning system for use when the vehicle is parked. Conventionally most trucks are manufactured without auxiliary power units. These are typically sold as a dealer installed option. However, with conventional auxiliary air-conditioning systems it is not feasible to utilize the ducts for the main air-conditioning system which are installed in the cab during original assembly of the vehicle. Adequate cab cooling is not achieved if cooled air from the auxiliary air-conditioning system is simply discharged at the floor of the cab. Accordingly it has been necessary in many cases to install new ducts in the cab for the auxiliary air-conditioning system. This means removing significant portions of the cab interior, both at considerable expense and with the risk of disturbing the integrity and appearance of the original interior. Accordingly, truck owners often find the entire procedure of installing conventional auxiliary air-conditioning units to be unsatisfactory.  
     SUMMARY OF THE INVENTION  
      According to one aspect of the invention, there is provided a method for providing for the installation of an auxiliary air-conditioning system for a vehicle having a vehicle engine for powering the vehicle and a main air-conditioning system powered by the vehicle engine. The main air-conditioning system includes a main compressor powered by the vehicle engine, an evaporator apparatus and a main condenser, the evaporator apparatus and the main condenser being connected to the main compressor by refrigerant conduits suitable for carrying a refrigerant. The method comprises installing independent first and second evaporator conduits in the evaporator apparatus for the main air-conditioning system, the first of the evaporator conduits being connected to the main compressor and to the main condenser. The second evaporator conduit has at least one fitting capable of connecting to an auxiliary compressor of an auxiliary air-conditioning system. The main air-conditioning system is installed in the vehicle at the time of original assembly of the vehicle.  
      There is provided, according to a second aspect of the invention, a method for installing an auxiliary air-conditioning system for a vehicle having a vehicle engine for powering the vehicle and a main air-conditioning system powered by the vehicle engine. The main air-conditioning system includes a main compressor powered by the vehicle engine, an evaporator apparatus and a main condenser. The evaporator apparatus and the main condenser are connected to the main compressor by refrigerant conduits suitable for carrying a refrigerant. The method comprises installing two independent evaporator conduits in the evaporator apparatus, a first of said evaporator conduits being connected to the main compressor and to the condenser. A second of said evaporator conduits has at least one fitting capable of connecting to an auxiliary compressor of an auxiliary air-conditioning system. The main air-conditioning system is installed in the vehicle at the time of original assembly of the vehicle. The auxiliary air-conditioning system is installed subsequent to original assembly of the vehicle. The auxiliary air-conditioning system is powered independently of the vehicle engine and has an auxiliary compressor, the auxiliary compressor is connected to said at least one fitting on the second evaporator conduit.  
      According to a third aspect of the invention, there is provided an air-conditioning apparatus for a vehicle having an engine, the apparatus comprises a main compressor powered by the engine, a main condenser connected to the main compressor, a first refrigerant conduit connecting the main condenser to the main compressor and an evaporator apparatus having two independent evaporator conduits. A second refrigerant conduit connects a first of the evaporator conduits to the main compressor. A third refrigerant conduit connects the first of the evaporator conduits to the main condenser. A second of the conduits of the evaporator has at least one fitting for connecting to an auxiliary compressor which is powered independently of the engine.  
      According to a fourth aspect of the invention, there is provided a vehicle having a vehicle engine and an air-conditioning apparatus. The air-conditioning apparatus comprises a main compressor powered by the engine, a main condenser connected to the main compressor, a first refrigerant conduit connecting the condenser to the main compressor and an evaporator apparatus having two independent evaporator conduits. A second refrigerant conduit connects a first of the evaporator conduits to the main compressor. A third refrigerant conduit connects the first of the evaporator conduits to the condenser. A second of the evaporator conduits has at least one fitting for connecting to an auxiliary compressor which is powered independently of the engine.  
      According to a fifth aspect of the invention, there is provided a vehicle having a vehicle engine, a cab and an air-conditioning apparatus. The air-conditioning apparatus comprises a main compressor powered by the engine, a main condenser connected to the main compressor, a first refrigerant conduit connecting the main condenser to the main compressor and an evaporator apparatus having two independent evaporator conduits. A second refrigerant conduit connects a first of the evaporator conduits to the main compressor. A third refrigerant conduit connects the first of the evaporator conduits to the condenser. A second of the evaporator conduits has at least one fitting for connecting to an auxiliary compressor which is powered independently of the engine. A common duct in the cab delivers cooled air when the main compressor is operational and when the auxiliary compressor is operational.  
      According to a sixth aspect of the invention, there is provided a vehicle having a vehicle engine, a cab and a main air-conditioning apparatus including a main compressor powered by the engine, a main condenser connected to the main compressor, and an evaporator apparatus connected to the main compressor and to the condenser. An auxiliary air-conditioning apparatus includes an auxiliary compressor powered independently of the vehicle engine. A common duct in the cab is used to deliver cooled air for both the main air-conditioning apparatus and the auxiliary air-conditioning apparatus.  
      According to a seventh aspect of the invention, there is provided a vehicle having a vehicle engine, a cab having an interior and a main air-conditioning apparatus including a main compressor powered by the engine, a main condenser connected to the main compressor, and an evaporator apparatus connected to the main compressor and to the main condenser. An auxiliary air-conditioning apparatus includes an auxiliary compressor powered independently of the vehicle engine, the auxiliary air-conditioning apparatus utilizing said evaporator apparatus; and ducts in the cab to deliver cooled air to the interior of the cab.  
      The invention offers significant advantages compared to the prior art. Mainly it allows an auxiliary air-conditioning system, powered by an auxiliary power unit, to be installed in the cab of a vehicle subsequent to the original assembly of the vehicle, but without requiring disassembly or alterations of the vehicle interior. This is accomplished because the subsequently installed auxiliary air-conditioning system can utilize the original ductwork installed for the main air-conditioning system. All this can be done without requiring alterations or replumbing of the main air-conditioning system.  
      Embodiments of the invention can utilize the original evaporator apparatus installed with the main air-conditioning system. Therefore they can utilize the original ductwork. This can be done by having the truck manufacturer install an evaporator apparatus with an additional conduit or coil. Refrigerant conduits for the auxiliary air-conditioning system can be connected to the additional coil without disturbing connections to the coil utilized for the main air-conditioning system.  
      One of the main advantages achieved is lower overall costs. The cost of an evaporator apparatus according to the invention is slightly more than a conventional evaporator, but much greater savings are made in simplified installation of the auxiliary air-conditioning system. No separate ductwork is required, no or little disassembly of the vehicle interior is necessary, and the cost of an additional evaporator is eliminated. This results in significant saving of space occupied by the auxiliary air-conditioning system. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      In the drawings:  
       FIG. 1  is a schematic view of an air-conditioning system for a vehicle including a main air-conditioning system operated by the vehicle engine and an auxiliary air-conditioning system operated by an auxiliary power unit independently of the engine, the main air-conditioning system having a condenser fan driven by an electric motor;  
       FIG. 2  is a view similar to  FIG. 1 , showing a variation of the invention where the main air-conditioning system has a condenser fan driven by the engine;  
       FIG. 3  is a simplified, diagrammatic side view of a tractor unit including an air-conditioning system as shown in  FIG. 1 ; and  
       FIG. 4  is a fragmentary, diagrammatic view of an evaporator apparatus according to an alternative embodiment of the invention having two heat exchangers. 
    
    
     DETAILED DESCRIPTIONS OF THE PREFERRED EMBODIMENTS  
      Referring to the drawings, and first to  FIG. 3 , this shows a tractor unit  1  of the type conventionally used for hauling trailers on highways. It includes a chassis  2 , a cab  3  with an interior  4 , front wheels  5  and rear wheels  6 . Only one wheel of each of the pairs of wheels is shown. There is also a trailer hitch  7  for connecting to a trailer. The vehicle has a factory-installed main air-conditioning apparatus  8  which includes ducts  9  for delivering cooled air to the cab as shown at  50 .  
      There is also an auxiliary power unit  25  which, in this example, is installed after assembly of the vehicle. Typically it may be included as a dealer installed accessory when the vehicle is new or added later, some time after the vehicle has been first used. An auxiliary air-conditioning compressor  27  is driven by the auxiliary power unit and may comprise part of the auxiliary power unit or may be separate.  
      Referring to  FIG. 1 , this shows details of the air-conditioning system including main air-conditioning apparatus  8  installed during original assembly of the vehicle and an auxiliary air-conditioning apparatus  42  usually installed later, typically by the vehicle dealer.  
      The main air-conditioning apparatus  8  includes a main compressor  10  powered, in this example, by continuous belt  11  connected to the vehicle engine  12 . The air-conditioning apparatus includes an evaporator apparatus  16  and a condenser  18  which, in this example, is associated with a condenser fan  44  driven by an electric motor  46 . In this example, as may be seen in  FIG. 1 , the evaporator apparatus includes a single heat exchanger  14 . The evaporator apparatus has a fan  91  powered by an electric motor  93  and forces warm air drawn from the cab of the vehicle over the conduits or coils of the evaporator apparatus where it is cooled and discharged into the ductwork  9  of the cab shown in  FIG. 3 . The evaporator apparatus is connected to the compressor by first refrigerant conduit  13 . The compressor is connected to the condenser by second refrigerant conduit  21 . Third refrigerant conduit  19  connects the condenser to the evaporator apparatus. As described thus far, the system is conventional and accordingly is not described in more detail.  
      The system departs from the conventional by having two conduits  15  and  23  in the evaporator apparatus  16 . For illustrative purposes these conduits are shown as being entirely separate, but they may be intertwined in an actual evaporator apparatus. The conduits  15  and  23  have first ends  50  and  52  respectively and second ends  54  and  56  respectively. In this example the conduits  15  and  23  are tubular coils, but could be other types of conduits, typically convoluted conduits which carry the refrigerant.  
      The embodiment of  FIG. 1  also departs from the conventional by having two conduits  17  and  33  in condenser  18 . As with the evaporator, the conduits are shown entirely separate for illustrative purposes, but actually may be intertwined. The conduits  17  and  33  have first ends  60  and  62 , respectively, and second ends  64  and  66 . The illustrated ends of these conduits, and the ends of the evaporator conduits described above, are fittings for connecting to other components, but the fittings may also be threaded or quick connect fittings or other types of fittings known in the art. As with the evaporator conduits, the condenser conduits in this example are tubular coils, but could be other types of conduits, typically convoluted conduits as shown.  
      There is a refrigerant conduit  35  which connects second end  56  of the second evaporator coil  23  with the second end  66  of second condenser coil  33 . All of the components described thus far would normally be provided by the vehicle manufacturer and would be installed in the factory during original assembly of the vehicle. Both the evaporator apparatus and the condenser in this example have second coils which are interconnected by the conduit  35 , the latter preferably also provided by the vehicle manufacturer and installed at the time of original vehicle assembly. However the second coils are not usually operational in the vehicle as originally assembled.  
      The auxiliary power unit  25  is conventionally installed subsequent to original assembly of the vehicle, often by the vehicle dealer. These units are well known and accordingly are not described in detail. They normally include a small diesel engine which is connected to the vehicle fuel supply. The small diesel engine is connected to an electrical generator or alternator for producing electricity to power the vehicle when engine  12  is stopped. In this particular example an auxiliary air-conditioning compressor  27  is incorporated into the auxiliary power unit. However the compressor may also be installed as a separate unit, but powered by electricity from the generator of the auxiliary power unit. The compressor  27  has an input port  70  receiving refrigerant through conduit  29  which is connected to first end  52  of the second coil  23  of the evaporator apparatus. The compressor has an output port  71  which is connected to first port  62  of second coil  33  of the condenser by conduit  31 .  
      In brief, the dealer or other person installing the auxiliary power unit and accompanying auxiliary air-conditioning system, installs, besides the auxiliary power unit  25  itself, the compressor  27  which may be part of the auxiliary power unit or separate. Also installed at the same time are the conduits  29  and  31 . The rest of the auxiliary air-conditioning apparatus  42  comprises pre-existing components installed by the vehicle manufacturer including the condenser  18  with its second coil  33 , evaporator apparatus  16  with its second coil  23  and the conduit  35  which connects the second coils of the evaporator and condenser.  
      A variation of the invention is shown in  FIG. 2  where like parts have like numbers with the additional designation “ 0 . 1 ”. In this example the main condenser  18 . 1  has fan  44 . 1  powered directly by engine  12 . 1  instead of by an electric motor such as electric motor  46  of the previous embodiment. Therefore the fan  44 . 1 , unlike fan  44  of the previous embodiment, cannot be operated when the engine is stopped. Thus neither compressor  10 . 1 , nor condenser  18 . 1  is utilized when the engine is stopped. However this variation is similar to the previous embodiment in having an evaporator apparatus  16 . 1  with two coils  15 . 1  and  23 . 1 . Coil  15 . 1  is utilized by the main air-conditioning system in a manner similar to the previous embodiment. Likewise coil  23 . 1  is utilized by the auxiliary air-conditioning system  42 . 1 .  
      This embodiment includes a separate auxiliary condenser  43  having a fan  45  powered by an electric motor  47  which receives power from the auxiliary power unit. The condenser has a single conduit or coil  79  with a first end  80  and a second end  81 . First end  80  of the coil is connected to first end  52 . 1  of second coil  23 . 1  of the evaporator apparatus by a conduit  90 . A conduit  91  connects second end  81  of the coil of the auxiliary condenser to port  70 . 1  on compressor  27 . 1  of the auxiliary power unit. Port  71 . 1  of the compressor is connected to second end  56 . 1  of the second evaporator coil by conduit  94 . This embodiment works in a manner similar to the previous embodiment, but requires the installation of the separate auxiliary condenser  43  along with its motor  47  and fan  45 . Only the evaporator apparatus is shared by the main air-conditioning apparatus  8 . 1  and the auxiliary air-conditioning apparatus  42 . 1 .  
      It may be understood with reference to  FIGS. 1 and 3  that the ductwork  9  in the cab of the vehicle is used in common by both the main air-conditioning apparatus  8  and the auxiliary air-conditioning apparatus  42  because the ductwork  9  receives cooled air from the evaporator apparatus  16  for the embodiment of  FIG. 1  and likewise evaporator apparatus  16 . 1  of the embodiment of  FIG. 2 , and the evaporator apparatus is shared by the main air-conditioning apparatus and the auxiliary air-conditioning apparatus in both embodiments.  
      A further embodiment is illustrated in the fragmentary view of  FIG. 4 . In this example, where like parts have like numbers as the embodiment of  FIG. 1  with the additional designation “ 0 . 2 ”, evaporator apparatus  16 . 2  includes two separate heat exchangers  90  and  92 . In this particular example the heat exchangers  90  and  92  are slightly spaced apart, but are positioned so air blown by fan  40 . 1  is directed over both heat exchangers. Alternatively the heat exchangers  90  and  92  can be sandwiched together or can be constructed as a single unit. They could also have separate fans. In this example evaporator conduit  15 . 2  comprises part of heat exchanger  90 , while evaporator conduit  23 . 2  comprises part of heat exchanger  92 . As with the previous embodiments, the evaporator conduits in this example are convoluted tubes within the heat exchangers, but could be other types of conduits in alternative constructions where, for example, the heat exchangers are cast with interior baffles or are fabricated from sheet metal. It should also be understood that alternative structures, similar to those discussed above, could be employed for the condenser  18  in the embodiment of  FIG. 1 .  
      It will be understood by someone skilled in the art that many of the details described above are given by way of example only and can be deleted or altered within the scope of the invention as set out in the following claims.