Abstract:
An apparatus having an engine-driven generator wherein the fuel tank, engine, air cleaner, muffler and battery are arranged in accordance with a space-saving design, and the size of the fuel tank is maximized. This is accomplished in part by placing the fuel tank and muffler at different elevations, so that the muffler does not limit the footprint of the fuel tank. In particular, the fuel tank is supported at an elevation above the engine, while the muffler is attached to and disposed on one side of the engine. The muffler occupies a space located between the battery and the air cleaner. The muffler outlet is disposed at an elevation lower than the elevation of the engine exhaust port.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    This invention generally relates to engine-driven power supplies. In particular, the invention relates to systems for supplying fuel to engines that drive power supplies, such as power supplies for welders.  
           [0002]    Engine-driven welding power supplies are well known, and may be driven either by a DC generator or an AC generator (also called an alternator-rectifier). An AC generator generally includes, in addition to an alternator, a reactor followed by rectifiers to provide a DC output. Electrical power produced by the generator as the engine drives rotation of the rotor is converted by known electrical components into useable welding power available at terminals.  
           [0003]    Typically the engine is an internal combustion engine that burns gasoline. The engine is started either electrically (using a battery) or manually (by pulling a pull-start cable). Initially the engine may run at an idle speed (e.g., 2,200 rpm), with the speed being increased to a running speed when a load is applied to the generator. To turn off the welding machine, the engine must be turned off. In the case of an electric-start engine, the engine can be turned off by returning a start or ignition switch to its OFF position. In the case of a pull-start engine, the engine can be turned off by pressing a kill switch. In the case of an electric-start engine, the battery can be used to power a fuel cutoff solenoid when the engine is turned off.  
           [0004]    A vital part of an engine-driven generator is the tank that holds the fuel for the engine. In early engine-driven welding machines, the fuel tank was located entirely within the base of the machine. A filler hole was provided in a top wall of the tank. A suitable removable cap could be screwed on to close the filler hole. Upon removing the cap, a fuel nozzle could be inserted into the filler hole for filling the tank with fuel.  
           [0005]    Although such prior fuel tanks served their intended purpose, they possessed certain disadvantages. For example, the top wall of the tank, and thus the filler hole, was at a low height on the welding machine, often only several inches above the floor. Consequently, a person filling the fuel tank was required to bend over to insert the fuel nozzle into the filler hole. A related drawback was that there was very little warning given to the person that the tank was approaching a full condition. As soon as the tank was filled up to the top wall, which was difficult to observe, any additional fuel would spill out the filler hole. The spilled fuel would run down the sides of the fuel tank and into the welding machine base, where it was impractical to wipe up. Fill gauges were often incorporated into the fuel tanks, but they were not sufficiently sensitive to indicate a full tank condition quickly enough to prevent spillover. Also, the filler hole was on one side of the welding machine, so that side of the machine could not be mounted against a wall.  
           [0006]    The Blue Star 3500 engine-driven welder/generator, commercially available from Miller Electric Mfg. Co., Appleton, Wisconsin, has an engine with a metal fuel tank mounted on top. The muffler is also located above the engine, thus limiting the size of the fuel tank.  
           [0007]    There is a continuing need for improvements in the design of engine-driven welders/generators. In particular, there is a need for improvements in the placement of various components of an engine-driven welder/generator that allow the size of the fuel tank to be maximized.  
         BRIEF DESCRIPTION OF THE INVENTION  
         [0008]    The invention is directed to an apparatus comprising an engine-driven generator wherein the engine, fuel tank, and muffler are arranged in accordance with a space-saving design, and the size of the fuel tank is maximized. This is accomplished in part by placing the fuel tank and muffler at different elevations, with the muffler underneath the fuel tank, so that the muffler does not limit the footprint of the fuel tank, and with the fuel tank above the engine.  
           [0009]    One aspect of the invention is an apparatus comprising: an internal combustion engine; a fuel tank designed to hold fuel for the engine; an electric generator driven by the engine; a muffler coupled to an exhaust port of the engine; and a support frame for supporting the engine, the fuel tank and the generator, wherein the fuel tank is supported at an elevation above the engine. The muffler comprises a canister that is disposed in a space located under and beside respective portions of the engine and a muffler outlet that is lower in elevation than the elevation of the exhaust port. The muffler outlet directs exhaust gas in a lateral direction away from the engine.  
           [0010]    Another aspect of the invention is a power generation system comprising: an internal combustion engine; a fuel tank designed to hold fuel for the engine; a muffler comprising a pipe having an intake port coupled to an exhaust port of the engine, a canister that muffles acoustic noise emitted from the exhaust port of the engine, and a muffler outlet for emitting exhaust gases that have passed through the canister; an electric generator driven by the engine; and a support frame for supporting the engine, the fuel tank and the generator. The muffler is attached to the engine. The muffler outlet is lower in elevation than the elevation of the exhaust port, the muffler outlet directing exhaust gas in a lateral direction away from engine.  
           [0011]    A further aspect of the invention is an apparatus comprising: an internal combustion engine; a fuel tank designed to hold fuel for the engine; an electric generator driven by the engine; a muffler coupled to an exhaust port of the engine; an air cleaner coupled to an air intake of the engine; and a support frame that directly or indirectly supports all of the foregoing components, wherein the fuel tank is supported at an elevation above the engine, while the muffler comprises a canister that is disposed in a space located toward one side of the support frame between the battery and the air cleaner.  
           [0012]    Other aspects of the invention are disclosed and claimed below.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]    [0013]FIG. 1 is a drawing showing an isometric view of an engine-driven welder/generator in accordance with one embodiment of the invention.  
         [0014]    [0014]FIG. 2 is a drawing showing another isometric view of the engine-driven welder/generator of FIG. 1, but with the top cover and muffler cover removed.  
         [0015]    [0015]FIG. 3 is a drawing showing an isometric view (from above) of the fuel tank incorporated in the engine-driven welder/generator depicted in FIG. 2.  
         [0016]    [0016]FIG. 4 is a drawing showing another isometric view (from above) of the fuel tank of FIG. 3.  
         [0017]    [0017]FIGS. 5 and 6 are drawings showing respective elevational views of opposite ends of the fuel tank of FIG. 3.  
         [0018]    [0018]FIG. 7 is a drawing showing yet another isometric view (from above) of the fuel tank of FIG. 3.  
         [0019]    [0019]FIG. 8 is a drawing showing a further isometric view (from below) of the fuel tank of FIG. 3.  
         [0020]    [0020]FIG. 9 is a drawing showing a top view of a heat shield to which the fuel tank of FIG. 3 is mounted. The heat shield is shown prior to being bent into its final configuration.  
         [0021]    [0021]FIG. 10 is a drawing showing a top view of the heat shield of FIG. 9 after bending.  
         [0022]    [0022]FIG. 11 is a drawing showing an elevational view of one side of the heat shield shown in FIG. 10.  
         [0023]    [0023]FIG. 12 is a drawing showing an elevational view of one end of the heat shield shown in FIG. 10.  
     
    
       [0024]    Reference will now be made to the drawings in which similar elements in different drawings bear the same reference numerals.  
       DETAILED DESCRIPTION OF THE INVENTION  
       [0025]    While the present invention will be illustrated with reference to a particular engine-driven welder/generator, it should be understood at the outset that the invention in its broadest scope may be applied to engine-driven generators not used in conjunction with or incorporated in a welding machine.  
         [0026]    One type of known AC generator-driven power supply comprises an engine, a generator having a rotor driven by the engine and having various stator windings for providing welding and auxiliary outputs induced by the driven rotor. An electronic field current controller board regulates the welding and auxiliary outputs of the generator. In a welder/generator, the stator comprises various windings (not shown), including a welding power output winding, an exciter winding and auxiliary power output windings. The welding power output winding provides current to one electrode typically located at the tip of a welding gun, while a ground clamp is attached to the workpiece. The welding power output winding produces a desired voltage potential difference across the welding electrodes.  
         [0027]    The generator may be either a three-phase or a single-phase generator. In response to current from the field current controller board, the rotor winding creates electromagnetic fields that induce current in the various stator windings. The main output of the power supply may be used for welding or for other purposes, such as plasma cutting or other high power loads. Generally, the auxiliary output windings are used to provide an auxiliary power output (current, voltage and/or power). The auxiliary output is often used to power tools, lights, etc., that require 110 VAC. Thus, the auxiliary output is typically 110 VAC, but may be 240 or 480 VAC.  
         [0028]    An engine-driven welder/generator  2  (without welding attachments) in accordance with one embodiment of the invention is shown in FIGS. 1 and 2. The unit comprises a support frame  4  in the form of a tubular roll cage, a top cover  6 , a welding control box  8 , an engine  10 , a muffler outlet  12 , a battery  14 , an electric generator  16  and an air cleaner  73  that filters ambient air entering the engine. The apparatus further comprises a fuel tank  20  for supplying fuel to the engine. The engine  10 , generator  16  and battery  14  are all mounted to the base of the support frame  4 , while the cover  6 , control box  8  and fuel tank are mounted to a pair of support members  58   a  and  58   b , seen in FIG. 2.  
         [0029]    Referring to FIG. 2, the support frame  4  comprises four generally vertical straight tubular members (only three, designated  50   a ,  50   b  and  50   c , are visible in FIG. 2) located at respective corners of the frame. The bottoms of respective pairs of the vertical tubular members are connected by a pair of tubular base members  52   a  and  52   b , while the tops of respective pairs of the vertical tubular members are connected by a pair of tubular cross members  54   a  and  54   b . As seen in FIG. 2, the support frame further comprises a first tubular support member  58   a  that spans the vertical members  50   b  and  50   c , and a second tubular support member  58   b  that spans the vertical member  50   a , and the fourth vertical member not visible in FIG. 2. The support member  58   a  overlies the base member  52   a , while the support member  58   b  overlies the base member  52   b . The support members each comprise a pair of mutually parallel straight sections offset from each other and connected by an oblique section that increases the bending strength of the support members. The support members  58   a  and  58   b  support a fuel tank assembly comprising a plastic fuel tank  20  mounted to a metal heat shield  21 , as will be explained in more detail below. The support members  58   a  and  58   b  also support the welding control box (not shown in FIG. 2).  
         [0030]    The support frame  4  further comprises a pair of support brackets  60 , only one of which is visible in FIGS. 1 and 2. The ends of the support brackets  60  are respectively welded to the base members  52   a  and  52   b . The engine/generator assembly is supported by the support brackets  60 . The battery  14  is also supported by one of the support brackets, except via the intermediary of a battery mounting tray mounted to the support bracket directly below, but not visible in FIGS. 1 and 2.  
         [0031]    Referring to FIG. 2, the welder/generator further comprises a muffler that reduces the amplitude of the acoustic noise emitted by the engine. The muffler has an outlet  12  that does not project beyond the plane defined by the tubular members  50   b ,  50   c ,  52   a  and  58   a . FIG. 1 shows the muffler outlet  12  protruding through a muffler cover  13  that is attached to a flange on the battery mounting plate by a bracket, while FIG. 2 shows the muffler with the muffler cover removed.  
         [0032]    As seen in FIG. 2, the muffler comprises a canister  71  and a curved pipe  72 . The pipe  72  couples an exhaust port of the engine  10  to an inlet (not shown) of the canister  71 . Typically, the canister  71  and pipe  72  are welded together. The inlet end of the pipe  72  is attached to the exhaust port of the engine  10 , while the muffler canister  71  is mounted to the engine via a bracket welded to the top of the muffler canister and bolted to the engine. The engine exhaust port (i.e., the muffler inlet) is located at an elevation higher than the elevation of the muffler outlet  12 .  
         [0033]    As seen in FIG. 2, the fuel tank  20  is disposed above the engine  10 . The output shaft (not shown) of the engine  10  and the rotor (not shown) of the generator  16  are coaxial. The welding control box occupies the space above the generator  16  in FIG. 2. The canister  71  is disposed in a space located under and beside respective portions of the engine  10 , that space in turn being located between the battery  14  and the air cleaner  73 . The battery  14  is disposed beside the generator  16 .  
         [0034]    The fuel tank assembly will now be described with reference to FIGS. 1 and 2. As seen in FIG. 2, the fuel tank  20  is mounted to a generally horizontal heat shield  21 , which is in turn attached to and spans the support members  58   a  and  58   b  of the support frame. The fuel tank  20  is filled via a threaded fill neck  22 . A gas cap (not shown) will be threadably coupled to the fill neck  22  to close the fuel tank. As seen in FIG. 1, the top cover  6  has a circular cutout  74  to allow access to the fill neck  22 , as well as a cutout  76  on the side of the cover to provide access to the spark plug (not shown) of the engine. The cutout  76  (see FIG. 1) in the cover  6  aligns with the relief  32  (see FIG. 2) in the fuel tank.  
         [0035]    The structure of the fuel tank is shown in detail in FIGS. 3-8. The fuel tank  20  is a generally box-shaped plastic structure made by a rotomolding process, whereby the thickness of the tank walls is relatively constant throughout the structure. The fuel tank  20  has a length and a width that are substantially greater than its height. The tank comprises a top and a bottom connected on four sides. The top has a fill neck  22  with external threads for screwing on the gas cap.  
         [0036]    Referring to FIGS. 3, 4 and  7 , the top comprises walls  24  and  34  that are domed toward the central fill point to allow air to escape. The top further comprises a lattice of stiffening ribs  26 . The top wall area  34 , which surrounds the fill neck  22 , is bordered on two sides and along a semicircular arc by stiffening ribs  26 , thus forming a fuel spillover trough. Since the wall is domed toward the fill inlet, any fuel that spills into the spillover trough will flow toward the edge of the fuel tank under the influence of gravity. At the end of the spillover trough, the fuel tank is in contact with the top cover. A drainage channel  36  (see FIGS. 4 and 7) formed on one side of the fuel tank provides an escape route for fuel spilled onto the spillover trough, thereby preventing fuel from pooling on top of the fuel tank. The drainage channel  36  is formed on the side of the fuel tank that faces away from the side of the welder/generator on which the muffler is disposed, thus allowing excess fuel to run down the side of the tank under the machine&#39;s cover and away from ignition sources.  
         [0037]    Referring to FIG. 8, the bottom comprises a lattice of stiffening ribs  46  that prevent the tank bottom from warping; a first cup-shaped molded structure  38  that forms a clearance trough inside the fuel tank for placement of a float gauge; and a second cup-shaped molded structure  40 , having an opening at the bottom, that forms a clearance trough for placement of a fuel shutoff valve. The opening in trough  40  receives the fuel line to the engine.  
         [0038]    Side wall  42  (see FIG. 3) comprises spaced bar-shaped regions that are semi-transparent, these bars forming a “sight” fuel gauge allowing someone to see the fuel level inside the tank through the semi-transparent regions. A relief  28  (see FIGS. 3 and 7) is provided along the edge where the side wall  42  meets the top of the tank, which relief faces the tubular cross member  54   b  shown in FIG. 2 and provides room for a person to grab cross member  54   b , for example, when manually moving the welder/generator. The side wall  42  is opposed by an opposite side wall  44  (see FIG. 4). The other side walls, running generally perpendicular to side walls  42  and  44 , are respectively shown in FIGS. 5 and 6.  
         [0039]    [0039]FIG. 5 shows the drainage channel  36  in flow communication with the spillover trough  34 . The edge of the tank can be raised at the end of the spillover trough so that the only avenue for fuel discharge is into the discharge channel.  
         [0040]    [0040]FIG. 6 shows the side of the fuel tank that is on the same side of the welder/generator as the muffler. As best seen in FIGS. 3 and 8, a relief  32  is molded into this side of the tank to provide access to the engine spark plug. As previously mentioned, the top cover  6  (see FIG. 1) has a cutout  76  that is aligned with the relief  32  at the side of the fuel tank.  
         [0041]    The heat shield  21 , shown in FIGS. 9-12, also has a cutout  60  that aligns with the relief, but at the bottom of the fuel tank, again to allow spark plug access. During welder/generator assembly, first the fuel tank is fastened to the heat shield, and then the fuel tank/heat shield assembly is fastened to the support frame. This is accomplished as follows.  
         [0042]    As previously described, the fuel tank is rotomolded from plastic material. In one embodiment of the present invention, a plurality of tapped inserts made of aluminum alloy (not shown in the drawings) are insert-molded into the bottom of the plastic fuel tank. These inserts are arranged to align with clearance holes in the heat shield when the bottom of the fuel tank is placed on the heat shield.  
         [0043]    The heat shield comprises a generally rectangular sheet of metal (e.g., steel) that is cut as shown in FIG. 9. The cuts include the cutout  60  for spark plug access as well as a pair of circular clearance holes  62  and  64  for passage of the cup-shaped structures ( 38  and  40  in FIG. 8) projecting from the bottom of the fuel tank. A small cutout, which will later align with the drainage channel on the fuel tank, is made on the side of the sheet opposite to the cutout  60 . In addition, the corners of the metal sheet are cut out as shown in FIG. 9. It should be noted that the margin  70  has longer cuts to provide clearance for the support members  58   a  and  58   b  (see FIG. 2) on that side of the heat shield. The margins  66 ,  68  and  70  of the heat shield are then folded in the same direction to positions substantially perpendicular to the plane of the sheet. Three views of the folded sheet are presented in FIGS. 10-12. The folded margins  66  at both ends of the heat shield serve to capture the support members  58   a  and  58   b , on which the heat shield will be seated, as explained below.  
         [0044]    After the fuel tank and the heat shield have been separately fabricated, the heat shield is mated with the bottom of the fuel tank, with cutout  60  in the heat shield aligned with relief  32  in the fuel tank, and with the molded structures  38  and  40  respectively passed through the clearance holes  62  and  64  in the heat shield. Then the heat shield and fuel tank are fastened together using screws. Each screw passes through a respective clearance hole in the heat shield and threadably engages a respective tapped insert in the molded fuel tank. Optionally, the inserts are not tapped and self-threading screws are used.  
         [0045]    The resulting heat shield/fuel tank assembly is then mounted to the support frame  4  as shown in FIG. 2, with the heat shield  21  disposed between the engine  10  and the fuel tank  20 . Opposing sections of the tubular support members  58   a  and  58   b  are captured between the folded margins  66  (see FIG. 9) of heat shield  21 . Those same folded margins are fastened to the support members using self-threading screws. The relief  32  in the fuel tank provides access to the engine spark in the space behind the opposing section of the tubular support member  58   a . The top cover  6  is then fastened to the support members  58   a ,  58   b  (see FIG. 1), also using self-threading screws.  
         [0046]    The invention provides numerous advantages. The fuel tank disclosed herein has a storage capacity greater than that of the fuel tank typically provided by the engine manufacturer. This allows the welder/generator disclosed herein to run for a longer period of time without refueling. In addition, the stiffening ribs on the bottom of the fuel tank prevent warping of the fuel tank bottom and, by raising the tank bottom away from the heat shield, provide air-insulated pockets that insulate the fuel tank from the heat generated by the engine. A further advantageous aspect is that the molded fuel tank is molded with a relieved area to provide access to the spark plug of the engine in the final assembly. Also the fuel tank is molded to have a spillover trough on the top and a discharge channel on the side that allows excess fuel to run down the side of the tank under the machine&#39;s cover and away from ignition sources.  
         [0047]    In accordance with an alternative embodiment of the invention, the heat shield can be eliminated. In this case, the fuel tank is not fastened to the support frame and instead is trapped between the support members  58   a  and  58   b  (see FIG. 2) and the top cover  6  (see FIG. 1).  
         [0048]    While the invention has been described with reference to preferred embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for members thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation to the teachings of the invention without departing from the essential scope thereof. Therefore it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims.