Patent Publication Number: US-6660967-B2

Title: Power box

Description:
FIELD OF THE INVENTION 
     The present invention relates to power generating units such as compressors, electrical generators and welding power supplies, and particularly units of this type that can be transported to a work site. 
     BACKGROUND OF THE INVENTION 
     Portable units that can be carried to a site are known, and a typical unit of this type, such as a TS 200, Model 5000 welder/generator sold by Burco/Mosa, includes an open, lightweight frame consisting of a metal shell on which is mounted an internal combustion engine directly connected to an alternator, which generates sufficient amperage to operate direct current welders and to provide some auxiliary alternating current for operating auxiliary equipment. A engine is also mechanically coupled to a compressor that may be used to provide the compressed air needed to operate a plasma cutting torch used in conjunction with the welding equipment. 
     While units of this type operate satisfactorily, they have several disadvantages. First, and most importantly, even though the welder/generator or compressor is portable, it is nevertheless difficult and time consuming to load and unload, then connect up the various components which are included in the system. More specifically, in a typical operation, the portable welder/generator, which may weigh approximately 400 pounds, is lifted onto the bed of a pickup truck. Because it is so heavy, it is usually placed at the rear of the bed to avoid unnecessary lifting, and because it is so big, it creates an obstacle that makes it difficult to place any significant equipment in the pickup truck. Next, the compressor, which is a separate unit and also heavy (e.g. 150 pounds), must be lifted and placed on the bed of the pickup truck. At the job site, these units are generally unloaded from the truck, and in any event, they must be connected to one another, and with the welding and plasma cutting equipment, all of which is time consuming and often requires additional lifting of heavy equipment. 
     Moreover, even though the individual components of the system are relatively heavy, they nevertheless can be stolen and carried away from the back of a pickup truck. Therefore, it is the general practice of those who use such equipment to unload and properly store the equipment in a secure location at the end of each working day, and again, this results is a significant amount of lifting of heavy equipment. The same is true for smaller, auxiliary tools that are used with these units, such as plasma cutters, mig welders and/or welding leads, all of which must also be removed from the truck and stored. 
     Finally, in such known units, the tubular frame in which the internal combustion engine and the alternator are carried is entirely open, and, as a result, workmen and others located near the equipment are constantly exposed to very high levels of noise resulting from the operation of the engine, the alternator, and the associated compressor unit. 
     Colella, U.S. Pat. No. 6,051,809, describes a welder/generator and compressor unit that is sized to fit in the bed of a pickup truck. Specifically, the unit has a generally T-shaped cross section, with a lower housing portion sized to fit between the bed walls of a standard pickup truck bed. The upper portion of the housing is somewhat wider, extending over and resting on the bed walls, thus forming the T-shape. On one end of the upper portion of the housing are controls for connection to the welder/generator and compressor. Within the housing are various components including an internal combustion engine, alternator, and air compressor, as well as a compressed air tank for storing compressed air produced by the compressor, a battery, electrical and compressed air connections and a storage area. The engine, alternator and compressor are mounted in longitudinal alignment, with the drive shaft of the engine directly mechanically driving the shaft of the alternator and also mechanically driving the shaft of the air compressor through a speed-reducing pulley arrangement. 
     The Colella device has the advantage of being easily transportable in the pickup truck bed, and having conveniently located controls and connections to permit use of all of the units without removal from the pickup truck. Furthermore, the enclosed housing provided in the Colella device allows for some reduction of noise. 
     Unfortunately, the device shown in the Colella patent has a number of drawbacks. First, there is no provision in the described device for storage of fuel for the engine. Presumably, a fuel tank would be provided within an unused portion of the housing or in the truck bed adjacent to the unit. In such a position, the tank would be difficult to access for refueling. Furthermore, in typical use, the Colella device would remain within the pickup truck bed at all times. Therefore, when the fuel tank (wherever positioned) is refilled, spilled fuel would fall into the housing or truck bed soiling the bed or housing and creating a potential safety hazard. Similarly, the Colella patent does not describe a purge valve for the compressed air tank which would be needed to purge condensed water from the tank. Typically, such a valve is located on the tank. However, such a location would be inconvenient. Also, when a purge valve on the compressed air tank is opened to purge water from the tank, water is likely to be emitted into the housing, introducing unwanted moisture into the housing. 
     A second difficulty with the Colella design is that it is sized to fill the entire width of a pickup truck bed. As a consequence, the unit can only be readily installed adjacent the tailgate of the truck bed, to the rear of the wheel wells, for the reason that the width of the unit prevents sliding the unit past the wheel wells. Although the unit may be lifted over the wheel wells to a forward position in a short bed truck, the unit may be required to be placed in a rearward position for the reason that a short bed truck permits insufficient space (only about one foot) for the Colella unit to fit between the wheel wells and forward end of the truck bed. Positioned in a rearward bed location, the unit limits other uses of the truck bed, as items must be lifted over the bed walls to be placed in the bed, rather than sliding those items into the bed via the tail gate. Furthermore, with the Colella unit in the truck bed, the length of the bed is shortened such that the bed may no longer accommodate typical construction materials such as plywood sheets. 
     A third difficulty with the Colella design arises when fitting the unit to pickup trucks of different makes and models. While there is, to a reasonable extent, a standard pickup bed width, there is no standard height for pickup bed walls. As a result, the intended fit of the Colella unit, to rest on the pickup walls, will likely be correct for only a certain class of pickups. When the unit is installed in other classes of pickups, it is likely to either rest on the floor of the truck bed with the upper housing sections inconveniently elevated above the top of the bed walls, or, alternatively, rest on the top of the bed walls but with a substantial gap between the bottom of the housing and the bed floor. In the former case, the housing floor would need to be designed to distribute weight to prevent damage to either the unit or truck bed when the unit is resting on its bottom surface. The only way to avoid such issues would be to reduce the height of the lower housing of the unit to a height less than the shortest bed wall in which the unit might be used, which would reduce the volume of the housing available for the identified components. 
     In addition to the foregoing difficulties, there is the further complication that the total weight of the various elements called for in the Colella patent can easily approach 800 pounds, exceeding the weight that can be supported by typical truck bed rails, and requiring substantial reinforcement of the upper housing portions to support the unit in the intended manner. 
     A further difficulty with the Colella unit arises from the manner in which elements are positioned within the housing. The longitudinal, mechanically coupled arrangement of the engine, alternator and compressor makes efficient use of the space; however, it hinders the efficient flow of cooling air to those elements since such units are typically designed to obtain or exhaust cooling air in the longitudinal direction, and each element is longitudinally abutting either another element or the housing and truck bed walls. As a consequence, cooling air flow may be restricted and/or heated air may be caused to flow from one unit onto another, limiting cooling. 
     Finally, the Colella unit, while portable, may have limitations in some environments where a pickup truck cannot be positioned close to the work area, for example, where welding is being performed deep within a structure, it may be inconvenient, or detrimental to weld power, to run long electrical leads carrying welder voltages and currents from an externally-parked pickup truck to the work site. 
     SUMMARY OF THE INVENTION 
     The present invention provides a compact, efficient and secure integrated power unit for use in a bed of a pickup truck. The integrated power unit of the present invention is fully self contained, user friendly and relatively quiet in operation. The integrated power unit of the present invention conveniently fits at the forward end of a pickup truck bed and even fits between the rear wheel wells of the truck bed. Further, the integrated power unit of the present invention can be adjustably assembled so that it can be easily installed in a wide range of different pickup trucks. The integrated power unit of the present invention is especially useful where a wide range of power requirements are necessary. The integrated power unit of the present invention readily provides regulated and unregulated compressed air and an electrical power supply, thereby providing power for a wide range of electrically and pneumatically powered tools. 
     According to the principles of the present invention and in accordance with the preferred embodiments, the invention provides an integrated power unit for use with a pickup truck. The power unit has a lower housing located between opposed side walls in the truck and an upper housing that extends from the lower housing and over a sidewall of the truck bed. An electrical power generating unit and a plurality of electrical breakers are also located in the lower housing. 
     In another embodiment, the lower housing of the integrated power unit has a lid movable with respect to the lower housing and a switch mounted in the lower housing to detect when the lid is opened and closed. The switch is electrically connected with the internal combustion engine and disables the engine in response to the lid being opened. 
     In a further embodiment of the invention, the integrated power unit has a compressor located in the lower housing connected to the electrical power generating unit. A compressed air tank is also located in the housing and is connected to the compressor. A control panel has a gauge fluidly connected to the compressed air tank for displaying fluid pressure within the compressed air tank. In one aspect of this invention, the control panel is mounted in the upper housing. In another aspect of this invention, the control panel has a switch for enabling and disabling the compressor. 
     In a still further embodiment of the invention, the integrated power unit has an internal combustion engine and a first air flow path within the lower housing for receiving cooling air from outside the housing and directing the cooling air past the engine to a location outside of the housing. In addition, the integrated power unit has a power converting unit connected to the engine and a second air flow path within the lower housing. The second air flow path receives cooling air from outside the housing and directs the cooling air past the power converting unit to a location outside of the housing. In various aspects of this embodiment, the air flow paths extend through different walls of the integrated power unit. 
     The above and other objects and advantages of the present invention will become more readily apparent during the following detailed description taken in conjunction with the drawings herein. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with a general description of the invention given above and the detailed description of the embodiments given below, serve to explain the principles of the invention. 
     FIG. 1 is a partial perspective view of the rear of an integrated power unit in accordance with the principles of the present invention. 
     FIG. 2 is a top elevation view of the integrated power unit of FIG.  1 . 
     FIG. 3 is a perspective rear view of a bolster disassembled from the integrated power unit of FIG.  1 . 
     FIG. 4 illustrates a control panel of the integrated power unit of FIG.  1 . 
     FIG. 5 illustrates a perspective view of a lower housing of the integrated power unit of FIG. 1 in which major components are shown disassembled therefrom. 
     FIG. 6 is a schematic drawing of one alternative air ventilation flow for the integrated power units of FIGS. 1 and 6. 
     FIG. 7 is a schematic drawing of another alternative air ventilation flow for the integrated power units of FIGS. 1 and 6. 
     FIG. 8 is a schematic drawing of a further alternative air ventilation flow for the integrated power units of FIGS. 1 and 6. 
     FIG. 9 is a schematic drawing of a still further air ventilation flow for the integrated power units of FIGS. 1 and 6. 
     FIG. 10 is a schematic drawing of yet another alternative air ventilation flow for the integrated power units of FIGS. 1 and 6. 
     FIG. 11 is a partial perspective front view of a bolster fuel tank with one end removed as used with the integrated power unit of FIG.  1 . 
    
    
     DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS 
     Referring to FIG. 1, an integrated electrical and mechanical power generating unit in accordance with the principles of the present invention can be further described. An integrated unit  10  is shown positioned within the bed of a full size pickup truck. The integrated unit  10  comprises upper housings  10   a  and  10   b  which form bolsters, and a lower housing  10   c  which rests in the bed of the pickup truck. 
     As will be discussed in further detail below, bolsters  10   a,    10   b  are vertically adjustable in the direction of arrow  12  so that bolsters  10   a,    10   b  may be positioned to rest upon the sidewalls  14   a,    14   b,  respectively, of the pickup truck bed. In this manner, bolsters  10   a,    10   b  rest upon the sidewalls  14   a,    14   b  of the pickup truck bed, while the lower housing  10   c  rests upon the floor  16  of the pickup truck bed. The greatest portion of the weight of the unit rests upon the pickup truck bed, with the bed walls supporting only the weight of the respective bolsters  10   a,    10   b.    
     Lower housing  10   c  includes feet  18   a,    18   b  which rest upon the floor  16  of the pickup truck bed, and thus hold lower housing  10   c  in a position somewhat above the floor  16  of the pickup truck bed. In this way, feet  18   a,    18   b  create a space or gap  20  beneath lower housing  10   c  which may be used for a storage drawer or for elongated cargo such as plywood sheets. 
     The rear surface of lower housing  10   c  includes an access door  24  providing access to a closet space  27  that is used to hold a welding power generator unit  44  (FIGS.  2  and  5 ). The lower housing  10   c  further includes a purging outlet drain  26  (FIG. 2) for emitting moisture purged from pressurized gas tanks within power generating unit  10 , as explained in further detail below. 
     It will be seen that the lower housing  10   c  of the power generating unit  10  is sized so as to fit between the wheel wells  28   a,    28   b  on a conventional full size pickup truck bed. This permits the power generating unit  10  to be positioned at any desired location within the pickup truck bed, including a fully forward position as shown in FIG. 1, a fully rearward position, and a position between the wheel wells  28   a,    28   b.    
     Referring to FIG. 2, details of the internal structure of power generating unit  10  can be explored. A first component within the lower housing  10   c  of the power generating unit  10  is an internal combustion engine  40 , such as an air cooled, two cylinder, gasoline engine, providing mechanical power for the remaining elements of the power generating unit  10 . Engine  40  is arranged longitudinally to produce mechanical torque on a shaft extending outward from engine  40  and into an alternator unit  42  that is separate from the engine  40 . Alternator unit  42  produces electrical power from rotation of the shaft of engine  40 , which electrical power may be used by other elements of the power generating unit  10 . 
     A first element using electrical power is a welding power supply  44  positioned, as noted above, behind door  24  to permit access thereto. Welding power supply  44  converts three-phase alternating current electrical power from alternator unit  42  into welding voltages to be used in electrical welding. Welding unit  44  may be docked into power generating unit  10  in the position shown in FIG. 2, or may be removed via door  24  to a remote location and used at that remote location for welding. In either case, conductors carry three-phase electrical power from alternator unit  42  to welding power supply  44 . 
     Engine  40 , alternator unit  42  and welding power supply  44  are contained within a first baffled compartment of lower housing  10   c.  A longitudinal baffle  47  extending longitudinally across the lower housing  10   c  separates engine  40 , alternator unit  42  and welding power supply  44  from a second baffled compartment containing compressors and air tanks as discussed below. This provides that the compartments have separate air flow paths to facilitate cooling, as is elaborated below. 
     Within this second compartment, air tanks  46   a,    46   b  store compressed air produced by compressors  48 - 51  positioned within the compartment above. Compressors  48 - 51  are electrically powered compressors driven by electrical power produced by alternator unit  42 . The compressors  48 - 51  have internal fans (not shown) that receive cooling air through inlets  101  that are directed toward the front wall  19 . The compressors  48 - 51  are oriented such that the inlets  101  are immediately adjacent the vents  74 - 76  (FIG.  5 ), so that there is a direct and unobstructed ventilation air flow through the vents  74 - 76  to the inlets  101  of the compressors  48 - 51 . Thus, respective longitudinal centerlines of the compressors  48 - 51  are nonperpendicular and angled with respect to a longitudinal centerline of the truck bed  15 . The angular orientation of the compressors  48 - 51  provides a plurality of parallel cooling air flow paths that better direct the cooling air around the welding unit  44  and into a compartment housing the alternator  42 . Compressors  48 - 51  generate compressed air which is stored within tanks  46   a,    46   b  and available as compressed air through a control panel in bolster  10   b  as is described in detail below. 
     Within the same compartment as compressors  48 - 51  and positioned above tanks  46   a,    46   b  is a battery  52  that is used to drive a starter of engine  40 . The battery  52  is supported by a bracket  30  that is mounted to the support plate  78  by fasteners, welding or other known means. The bracket  30  bounds an enclosed volume in which a capacitor pack  32  is located. 
     Referring to FIG. 2, air tanks  46   a ,  46   b  are purged by a hose  54  connected to a manual push button purge valve  108  in bolster  10   b  and a hose  55  connected between the purge valve  108  and purge outlet  26 . To purge excess moisture from air tanks  46   a ,  46   b , this manual purge valve within control panel  25  is actuated, causing compressed air to force moisture through hoses  54 ,  55  and out outlet  26 . 
     Standoff pads  87  are fixed to the front wall  19  of the lower housing  10   c.  The standoffs  87  are made of a resilient material and are used to position the lower housing  10   c  a desired distance from the front wall  23  of the truck bed  15 . The space provided by the standoff pads  87  between the front truck bed wall  23  and the front wall  19  of the lower housing  10   c  permits air to circulate adjacent the front wall  19  and enter the vents  74 - 76  (FIG.  5 ). 
     Referring to FIG. 5, the top of lower housing  10   c  has an opening  105  coverable by a top door or lid  82 . The opening  105  is surrounded by a mounting frame  80  for the lid  82 . The lid  82  may be completely removable from the mounting frame  80  or be pivotally connected to the mounting frame  80  by means of a hinge  83 . One or more latches (not shown) can be used to secure the lid  82  to the lower housing  10   c.  Compressed air lifters (not shown) can be interposed between lid  82  and lower housing  10   c,  so that lid  82  will move to, and hold, an open position when the latch is released. The lid  82  has a peripheral groove inside its outer edge  69  that extends over and mates with a peripheral lip or standing seam  71  on mounting frame  80 . That lip in groove construction provides a tight, rain-proof seal around the lid  82  and directs water away from the interior of lower housing  10   c.  Further, that construction provides greater sturdiness and security to the lid, thus making it more impervious to unauthorized entry. Similarly, surrounding the opening  105  of the lower housing  10   c  is a standing lip or seam (not shown) that fits inside a peripheral groove of the mounting frame  80 . Again, that mechanical construction provides an excellent rain-proof seal and further provides rigidity to the lower housing  10   c,  thereby increasing the security of the lower housing  10   c.    
     An electrical disconnect or “kill” switch  85  (FIG. 2) is mounted in the lower housing  10   c  adjacent an edge of the mounting frame  80  opposite the hinge  83 . The switch  85  changes state in response to detecting the proximity of the movable forward edge of the lid  82 , thereby providing an electrical signal that changes state in response to the lid  82  being opened and closed. The switch  85  is used as an electrical disconnect or “kill” switch for the engine  40 . The switch  85  is electrically connected with electrical components in the internal combustion engine  40  such that when the lid  82  is opened, the switch  85  changes state, thereby terminating the operation of the engine  40 . The switch  85  changes state again when the lid  82  is closed, thereby permitting the engine  40  to be restarted. As will be appreciated, the switch  85  can alternatively be mounted in the lid  82  or disposed at other locations that permit the switch  85  to detect an opening and closing of the lid  82 . As will further be appreciated, the switch  85  can be a limit switch or other suitable proximity switch; and further, the switch  85  can be connected with the wiring of the engine  40  in different ways to achieve the desired result. 
     Opening the lid  82  provides access to the breakers  92  that are mounted within an electrical box or cabinet  93 . As shown in FIGS. 2 and 5, a breaker box  93  is mounted on top of a housing  95  that forms a compartment for the alternator  42 . 
     Referring to FIGS. 2 and 5, a first ventilation air flow path  65  is used to cool the engine compartment  57 ; and a second ventilation air flow path  67  is used to cool the other components in the lower housing  10   c.  The engine compartment  57  is formed by baffles  47 ,  53  and alternator housing  95 , thereby isolating it from the other components in the lower housing  10   c.  Thus, the cooling of the engine  40  is separate from the cooling of the other components within the lower box  10   c.    
     Within the engine compartment  57 , the internal combustion engine  40  has an expanded air inlet duct  59  that supplies both ventilation and combustion air to the engine  40 . The duct  59  is generally conically shaped with an inlet end  61  that is substantially larger than the duct outlet  63 . Thus, any impediment to air flow into the engine  40 , for example, a resistance to air flow presented by a vent  91  in the right end wall  21 , is substantially eliminated. The engine  40  has a generally cylindrically shaped muffler  34  (FIG. 5) that is mounted within a plenum  35 . Air drawn through the duct  59  is blown by a fan in the engine  40  into the plenum  35 , around the muffler  34  and out through an upper portion  36  of an air vent  37  mounted on the rear wall  17 . Thus, the muffler  34  is completely surrounded by cooling and insulating air that is continuously circulated within the plenum  35 . The plenum  35  minimizes a transfer of heat from the muffler  34  to the interior of the lower housing  10   c.  The cooling air flow path around the engine  40  is generally shown by the flow path line  65  in FIG.  2 . 
     The compressors  48 - 51  and other units to the front of the lower housing  10   c  are cooled by air flowing in through vents  74 - 76  located on the front wall  19 . The alternator  42  has a fan  77  disposed within the opening  99  to provide other forced air ventilation within the lower box  10   c.  The alternator fan  77  and fans (not shown) in the compressors  48 - 51  draw cooling air through the vents  74 - 76 , around the compressors  48 - 51 , past the left end wall  23 , past the welding unit  44  and into the alternator housing  95 . The air is discharged through a lower portion  38  of the air vent  37  on the rear wall  17 . The area of the vent  74  is larger than the area of the vent  75  that, in turn, is larger than the area of the vent  76 . The area of the vents  74 - 76  is varied to equalize the flow of ventilation air over the components adjacent the front wall  19 . The cooling air flow path for the compressors  48 - 51 , welding unit  44  and alternator  42  is generally shown by the flow path line  67  of FIG.  2 . 
     As seen in FIG. 5, the air vent  37  has ventilation holes  41  extending through the rear wall  17  of the lower housing  10   c,  thereby directing ventilation air straight out generally parallel to the floor  16  of the truck bed  15 . A second, vent  45  is mounted immediately in front of, but displaced away from, the ventilation holes  41 . The vent  45  is constructed with a plurality of parallel louvers  45  that are mounted at an angle in order to direct exiting ventilation air upward. Without the louvers  45 , heated ventilation air exiting from the ventilation holes tends to circulate in the truck bed, hindering cooling and tending to heat other items stored in the truck bed  15 . To minimize that heating effect, the louvers  45  are used to direct the heated exhaust air up away from the truck bed floor  16 . As will be appreciated, alternatively, the vent holes  41  and vent  45  may be mounted to a panel that is completely removable from, or hinged to, the rear wall  17 . 
     Bolster  10   a  is a tank storing fuel for internal combustion engine  40 . Specifically, tank  10   a  is a fuel tank for storing fuel to be used by engine  40 . The capacity of the fuel tank and bolster  10   a  is sufficient to maintain operation of engine  40  for at least one entire day of operation at a job site. The tank in bolster  10   a  may be refueled through an opening (not shown) in the bolster  10   a  that is closed or sealed in a known manner by a refueling cap  56  mounted on the outside surface of bolster  10   a.  Fuel filler cap  56  is located on a left side of the pickup truck and thus, on a standard pickup, will be adjacent to the fuel filler cap of pickup truck itself. Thus, fuel can be readily dispensed into the fuel tank of the pickup truck as well as into the fuel tank of the power generating unit  10 . It will be further noted that the position of the fuel filler cap  56  is at an outward edge of a bolster  10   a  and further, that the outer edge of bolster  10   a  extends outward of the bed wall of a typical pickup truck. As a consequence, any fuel. spillage that occurs while filling the fuel tank in bolster  10   a  will flow to an area outside of the pickup truck bed, thus minimizing safety hazards from spilled fuel. 
     Referring to FIG. 11, a filler tube  68  has an upper, proximal end contiguous with the opening  107  of the fuel tank and a lower, distal end extending close to the bottom  109  of the fuel tank in bolster  10   a.  The filler tube  68  has a flapper valve (not shown) located at its upper end immediately adjacent the opening  107  in the fuel tank. The flapper valve is normally in a closed position blocking the filler tube  68 , and the flapper valve is opened by a fuel nozzle being inserted therethrough to fill the tank. With the truck upright and the lower end of filler tube  68  near the bottom  109  of the tank, the filler tube  68  functions as a flame arrester by helping to prevent a flame from reaching more volatile vapors that are normally in an upper portion of the tank. 
     Referring to FIG. 3, the adjustability of the bolster position can be further explained by mountings on the opposite surface of the lower housing section can be illustrated. As illustrated in FIG. 3, bolster  10   a  is detached from the lower housing  10   c  to show the connections therebetween. Specifically, bolster  10   b  has on its rear surface six threaded studs  72  which are positioned to fit within six holes  70  on lower housing  10   c.  Washers and nuts  73  are threaded onto stud  72  after stud  72  is inserted through holes  70 , to hold the bolster  10   b  in a desired vertical position. Holes  70  are elongated in a vertical direction thus permitting vertical adjustment in the position of a bolster. Similar connections are used with the bolster  10   a  to provide adjustability of the height of bolster  10   a.  Additional structures such as extender panels, positioned between housing section  10   c  and the bolster, can be used for horizontal adjustment of the position of the bolsters  10   a,    10   b,  if such is desired to permit fitting the power generation unit to a given pickup truck. 
     Referring to FIG. 4, a control panel  25  for the power generating unit  10  is mounted on bolster  10   b.  The alternator  42  provides power for four 120 volt 20 amp, ground fault interrupt (GFI) protected receptacles  81 , a single phase, 230 volt, 30 amp receptacle  89  and a three-phase, 230 volt, 30 amp receptacle  84 . Thus, substantially all of the electrical devices that might be operated with the power generating unit can be connected to an appropriate electrical connection. The three phases of electrical power from alternator unit  42  are protected by the triple circuit breaker  92  (FIG. 2) to provide interruption in the case of excessive current. 
     Further, the control panel  25  has electrical connections in the form of an R, S and T connector set  86  for providing three-phase electrical power used with a welding power supply. As noted above, when welding unit  44  is removed for use at a remote location, connections may be made to connectors  86  to the remote location to provide power to the welder power supply. In such a situation, remote control signals may be provided through a connector  88 . When a welding connection or another high voltage connection is made to the power generating unit, a ground terminal  90  may be used to provide adequate grounding for the unit and the tools being used therewith. 
     In addition, the control  25  panel has controls for the internal combustion engine  40  within the power generating unit. Specifically, a choke control, engine start button and rpm switch  94 ,  96 ,  100 , respectively, are used to start the engine as is known in the art. The engine ignition is enabled by run enable switch  98 , as is also known in the art. Further, readouts provide information on the engine condition. For example, high engine temperature is identified by a warning lamp  102 . A count of the total running hours of the internal combustion engine is provided by a meter  104 . Finally, a low engine oil condition is identified by a warning lamp  106 . 
     As noted above with reference to FIG. 2, a manual purge valve  108  is incorporated into the control panel  25  of the power generating unit. By actuating this control valve on the control panel, an operator may purge the air storage tanks  46   a,    46   b  without need to access those tanks within the power generating unit. This facilitates tank purging and thus insure that the tanks are purged at the appropriate schedule. 
     The control panel  25  also includes controls and readouts for pressurized air produced by the power generating unit. Three connectors  114   a,    114   b,    115  provide pressurized air from the power generating unit. The connectors  114   a,    114   b  are fluidly connected to respective air regulating valves  110   a,    110   b.  The air pressures being provided to the connectors  114   a,    114   b  is measured and displayed by respective air pressure gauges  112   a,    112   b.  The connector  115  provides a source of unregulated tank air that is measured and displayed by pressure gauge  113 . The control panel  25  also has a compressor switch  103  that functions to respectively enable and disable stop the compressors  48 - 51 , for example, turn the compressors  48 - 51  on and off. 
     The control panel may also include a remote actuator for opening a latch holding down a lid or top  82  (FIG. 5) on lower housing section  10   c.  The remote handle may be connected by a cable to the latch so that the lid for the lower housing section  10   c  can be opened from the control panel. 
     Referring to FIG. 5, the assembly of components of the power generating unit can be explained in further detail. Specifically, lower housing  10   c  is assembled by initially mounting each of the power generating units, such as the internal combustion engine  40 , air tanks  46 , compressors  48  and battery  52  onto a support plate  78 . Support plate  78  has cushioned mounting feet  79  to provide vibration reduction when support plate  78  is mounted in lower housing  10   c.  It can be seen that baffle  47  discussed above is inserted between the power generating components on support plate  78  to divert and control the flow of air through compartments of the lower housing  10   c  once the unit is assembled. FIG. 5 further illustrates the removable power welding unit  44 , which is installed into lower housing  10   c  through door  24 . As noted above, welding power supply  44  is portable and can be carried to work site or installed into lower housing  10   c  for use at the location of the power generating unit  10 . 
     In the embodiment described with respect to FIGS. 1-5, two separate ventilation air flow paths are used to cool the engine compartment  57  and the other components in the lower housing  10   c.  As will be appreciated, other ventilation air flow paths may be more effective. For example, referring to FIG. 6, a capped vent  118  can be mounted on the top of the lid  82  to provide a ventilation air discharge path through the top of the lower housing  10   c.  In this embodiment, the air flow path  120  for the engine  40  would be vented into the plenum  35  (FIG. 5) and then vented out the top of the plenum  35  via an appropriate duct. The second air flow path  122  could be vented out of the top of the alternator housing  95  on the left side of the baffle  53  and vented up to the outlet vent  118  (FIG. 6) via appropriate ducting. Alternatively, the ventilation air may be vented out the top of the housing  95  on the right hand side of the baffle  53  and into the plenum  35  to facilitate cooling of the muffler  34  and thereafter, ducted to the outlet vent  118 . As will be appreciated, some relocation of components, for example, breaker box  93 , may be required to accommodate these alternative ventilation air flow paths. 
     Referring to FIG. 7, another embodiment of ventilation air flow paths is schematically illustrated. The air flow path  67  is identical to that previously described with respect to FIG.  2 . However, the engine compartment  57  is cooled by receiving ventilation air from the front side  19  of the lower housing  10   c.  With this embodiment, a vent is added to the front side  19 ; and a duct  124  provides ventilation air along air flow path  126 . Once ventilation air is inside the engine compartment  57 , it is routed to provide a cooling effect in a manner similar to that previously described with respect to ventilation air flow path  65 . The duct  124  would extend from the front wall  19  and between the bracket  30  (FIG. 5) and the right end wall  21 . The duct  124  would also require an appropriate cutaway in the baffle  47  to obtain access to the engine compartment  57 . 
     In a further embodiment of ventilation air flow paths that is schematically illustrated in FIG. 8, the engine compartment  57  is cooled with a ventilation air flow path  65  as previously described. The remainder of the interior of the lower housing  10   c  is cooled by an air flow path  128  that receives ventilation air through vents located in the left end wall  23  of the lower housing. As will be appreciated, such inlet vents in the end wall  23  may be used in place of the vents  74 - 76  in the front wall  19  or in combination with such vents. In that event, the cross-sectional area of the various vents would be adjusted to provide the desired air flow patterns and cooling effect. 
     FIG. 9 is a schematic illustration of another alternative embodiment for providing ventilation air to the lower housing  10   c.  In this embodiment, ventilation air path  130  is provided through a bolster  10   b.  A vent  132  is constructed on top of the bolster  10   b,  thereby allowing ventilation air to circulate through its interior. Contiguous ventilation holes are provided in the rear wall  134  of the bolster  10   b  in the right end wall  21  of the lower housing  10   c  to permit the ventilation air flow path to enter the interior of the lower housing  10   c.  As will be appreciated, the ventilation air flow path  130  may be routed within the lower housing  10   c  to provide cooling for the engine  40 , other components within the lower housing  10   c  or all of the components therein. Air flow through bolster  10   b  can also provide cooling to wiring for the control panel  25  when located in bolster  10   b.    
     A still further embodiment for providing ventilation air is schematically illustrated in FIG.  10 . In this embodiment, one or more ventilation air flow paths  136 ,  138  are provided by ventilation holes in the bottom  140  of the lower housing  10   c.  In addition, ventilation holes would also be provided at appropriate locations in the support plate  78 . As will be appreciated, ventilation air between the support plate  78  and the bottom  140  may be provided by vents at the appropriate location in the side walls of the lower housing  10   c.    
     While the present invention has been illustrated by a description of various embodiments and while these embodiments have been described in considerable detail, there is no intention to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications will readily appear to those skilled in the art. For example, plate  78  might not be used; and in its place, units inside of lower housing section  10   c  could be mounted directly to the floor of lower housing section  10   c.  Each of the vibration-generating units (e.g., the compressors, engine and alternator) could be provided with vibration insulating feet where they mount to the lower housing section  10   c.  Further, in the described embodiment, two upper housings  10   a,    10   b  are attached to the lower housing  10   c.  As will be appreciated, in other embodiments of the invention, only one of the upper housings could be used. Further, the engine  40  is described as an air cooled, gasoline engine. However, as will be appreciated, other types of engines can be used, for example, a liquid cooled engine or a diesel engine, etc. 
     The invention in its broader aspects is, therefore, not limited to the specific details, representative apparatus and method, and illustrative example shown and described. Accordingly, departures may be made from such details without departing from the spirit or scope of Applicant&#39;s general inventive concept.