Abstract:
A generator support plenum and engine-generator set for installation on a pickup truck in an RV or on a boat, for example, sits in or under or forms a part of an enclosure for the engine-generator set and defines cool air flow paths into the set for cooling the engine and generator and aspirating the engine. The plenum also defines a warm air outlet duct for escape of the cooling air. In the outlet duct a diffuser couples to the exhaust of the engine to mix hot exhaust with the much cooler escaping cooling air that has passed over the engine and generator. The diffuser eliminates the effect of the extreme hot exhaust gas and muffles the engine sound. Insulation coating the internal surfaces of the plenum further suppresses engine noise.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority from the provisional patent application Ser. No. 60/470,011 filed May 12, 2003 in the name of Gerald S. Piercey, III entitled “Compressor Mount Plenum” incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    This invention relates to an intake and exhaust plenum for a generator and more particularly to a plenum that supports the generator. 
       BACKGROUND 
       [0003]    Generators used with recreational vehicles (RVs), on boats and those mounted on trucks for use at a worksite more often than not are intrusively noisy and direct hot exhaust fumes where they should not. In older RV parks, for example, insufficient electrical service often is available for when the park is well-filled with newer RVs that boast a multiplicity of electrical appliances, air conditioners and the like. Where that is the case, RV owners typically crank up their own generators. Generally these are too noisy for use in a crowded RV park, and often gasoline engine exhaust is directed out the side directly towards the next door neighbor. When the generator is in or on the RV itself, vibrations as well as noise will plague the RV occupant. Moreover, an on-board generator is (or can be) a fire hazard. 
         [0004]    Likewise, at a worksite, noise and noxious exhaust fumes can, again, annoy persons in the neighborhood of a truck-mounted generator. And the generator may be run for hours on end. Emission of very hot exhaust from the internal combustion engine of an engine-generator set is a hazard to neighbors, pets and close-by objects in a tightly populated camp site or RV park. 
         [0005]    A further problem that has arisen in connection with engine-generator sets used to power electrical appliances on houseboats, yachts and the like has been the collection of carbon monoxide in living and sleeping quarter. In at least one locality where vacationers regularly rent houseboats, sickness and fatalities have occurred. 
         [0006]    RV owners who would appreciate relocation of a noisy generator may not want an engine-generator set sitting on the tow vehicle. A metal toolbox spanning the bed of a pickup truck directly behind the cab is viewed as aesthetically permissible by RV users and other pickup truck owners, but a freestanding, installed generator is not necessarily so-viewed. 
         [0007]    There is a need, therefore, for a generator housing and support that reduces noise, correctly directs and dilutes engine exhaust and has a neat and acceptable appearance. 
       BRIEF SUMMARY 
       [0008]    The invention relates to a plenum that (1) cools hot exhaust exiting an engine-generator set, (2) channels engine cooling air and air for combustion into the generator enclosure, (3) mounts or supports the generator neatly inside a pickup toolbox or other enclosure, and (4) reduces noise. In one embodiment, a generator support truck for example, the plenum fits within a containment box which is the toolbox of a pickup and opens through openings formed in a wall of the box. (By “wall” is meant the box&#39;s bottom, lid or any of its upright walls.) In another embodiment the plenum supports the toolbox itself within which the generator is contained and communicates through openings through a toolbox wall. In a third embodiment the plenum and toolbox are combined into a single unit. Removal of the generator to the tow vehicle, away from the RV, reduces the risk of fire and eliminates the vibration of the RV. Exhaust can be directed away from the RV and any neighbor. 
         [0009]    In the case where an engine-generator set must be located in the generator compartment of an RV, the containment box and plenum of the invention can still improve the problems of noise and hot exhaust gas being wrongly directed. In several exemplary preferred embodiments, the box and plenum with air intake ducts opening to atmosphere draw in air to aspirate the engine and cool the engine and generator, while cooling air being exhausted is intermixed with hot exhaust before expulsion from the generator-containing box. In one case the box protrudes through the floor of the RV generator compartment and has openings into the plenum and out of the plenum through sidewalls just below the floor of the compartment. In another case floor openings in an RV generator compartment align with openings into the air intake duct and out of the air outlet duct. 
         [0010]    Hot exhaust from the internal combustion engine is mixed with warmed cooling air that, while warm, is nevertheless very much cooler than the exhaust, and the intermixed gasses are dispersed from an outlet duct formed by the plenum. Diffusers of various shapes and designs can be connected to the tailpipe of the internal combustion engine driving the generator. Holes along the length of the diffuser emit the hot exhaust into the cooler, cooling air that is on its way to atmosphere. Thus intermixed, the gaseous output from the box that houses the engine-generator set is far cooler and safer than hot exhaust. 
         [0011]    The above and further objects and advantages of the invention will be better understood from the following detailed description of at least one preferred embodiment of the invention, taken in consideration with the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]      FIG. 1  is a perspective view of a toolbox-style enclosure for a generator and housing a generator support plenum; 
           [0013]      FIG. 2  is a fragmentary perspective view of the enclosure of  FIG. 1  with the generator removed to expose the plenum; 
           [0014]      FIG. 3  is a fragmentary perspective view of the enclosure of  FIG. 1  and the plenum and illustrates aligning openings through the enclosure into the plenum; 
           [0015]      FIG. 4  is a perspective view of the plenum of  FIG. 3 ; 
           [0016]      FIG. 5  is a top plan view of the plenum of  FIG. 3 ; 
           [0017]      FIG. 6  is a front elevation view of a further embodiment of the enclosure of  FIG. 1  with parts broken away for clarity; 
           [0018]      FIG. 7  is a side cross-sectional view of a further embodiment of an enclosure and plenum according to the invention; 
           [0019]      FIG. 8  is a front elevation view of the enclosure and plenum of  FIG. 7 ; 
           [0020]      FIG. 9  is a fragmentary cross-sectional view of an exhaust diffuser located in a duct within a plenum in accordance with the invention; 
           [0021]      FIG. 10  is a top plan view, partly in cross-section, of the diffuser of  FIG. 9 ; 
           [0022]      FIG. 11  is a fragmentary perspective view of a further exhaust diffuser in a duct in the plenum of the invention; 
           [0023]      FIG. 12  is a cross-sectional view of the diffuser of  FIG. 11 ; 
           [0024]      FIG. 13  is a fragmentary cross-sectional view of a further embodiment of a diffuser in a duct in a plenum according to the invention; 
           [0025]      FIG. 14  is a top plan view, partially in cross-section, of the diffuser of  FIG. 13 ; 
           [0026]      FIGS. 15 and 16  are fragmentary perspective views of a toolbox with generator support and cooling provisions in accordance with a further embodiment of the invention and showing in  FIG. 15  the box open and in  FIG. 16  the box closed, both installed in a pickup truck; 
           [0027]      FIG. 17  is a diagrammatic illustration of a toolbox-style generator installation in accordance with the invention mounted on a house boat; 
           [0028]      FIG. 18  is a fragmentary cross-sectional and diagrammatic view illustrating a toolbox-type enclosure and plenum for a generator installed through the floor of an RV generator compartment; 
           [0029]      FIG. 19  is a fragmentary cross-sectional and diagrammatic view of a toolbox and plenum generator installation installed within an RV generator compartment and opening through holes in the compartment floor; 
           [0030]      FIG. 20  is a cross-sectional top view of a plenum illustrating a spiral wound diffuser; 
           [0031]      FIG. 21  is a top cross-sectional view of a plenum illustrating a generally U-shaped diffuser; 
           [0032]      FIG. 22  is a cross-sectional side view of a plenum diagrammatically illustrating the U-shaped diffuser of  FIG. 21 ; 
           [0033]      FIG. 23  is a fragmentary end view of the box of  FIGS. 15 and 16 ; 
           [0034]      FIG. 24  is a top plan view of the box of  FIGS. 15 and 16  with lid open; 
           [0035]      FIG. 25  is a perspective view with parts broken away for clarity of a further embodiment of the combined generator plenum and enclosure of the invention; and 
           [0036]      FIG. 26  is a fragmentary perspective view of the plenum and enclosure of  FIG. 24  showing the cool air intake opening therein. 
       
    
    
     DETAILED DESCRIPTION 
       [0037]    In  FIG. 1  an engine-generator set  10  supported by the plenum  20  in a toolbox  15 . The engine-generator set  10  is referred to on occasion here as the generator  10  or the “generator” as such usage is common. A central wall  22  ( FIG. 2 ) conforms a pair of ducts  23  and  24  to the gas intake and output provisions (not shown) of the engine-generator set  10  having an outer case  11 . 
         [0038]    The duct  23  of  FIG. 2  is the air intake duct and fits under openings in the case  11  ( FIG. 1 ) through which the generator  10  draws cooling air into the generator enclosure and over the internal combustion engine and generator. It, the duct  23 , also fits under and opens into an ignition air intake opening in the generator case  11  that provides air for combustion within the internal combustion engine that drives the generator. 
         [0039]    The duct  24  is the air outlet duct that allows the escape of the cooling air and also the exhaust of the generator driving engine. Into the duct  24  flows the cooling air exiting the generator enclosure and the hot exhaust from the engine&#39;s tail pipe. The escaping cooling air is ordinarily warm, but far cooler than the hot exhaust from the engine. The term “warm cooling air” used herein means simply cooling air raised in temperature by its passage over and around the generator and engine. The mixing of air and exhaust to cool the exhaust is safer for individuals and objects near to the emergent gases, and it also protects sound-proofing applied to interior duct surfaces for noise abatement. In a preferred embodiment a diffuser assures the thorough mixing of the hot exhaust into the much cooler escaping cooling air. Specific diffusers for this purpose are discussed below in connection with  FIGS. 9-12 . 
         [0040]    In  FIG. 3  openings  26  and  27  of the plenum can be seen. With the plenum in place in the box  15 , the opening  26  that draws in air aligns with an opening  29  in the face of the box. The opening  27  of the plenum aligns with an opening  30  for emission of the intermixed cooling air and exhaust. The central wall  22  stands as a partition between the cool intake air in duct  23  ( FIG. 5 ) and the much warmer and mixed air and exhaust in duct  24  ( FIG. 5 ). A suitable resilient seal runs along the top of the wall  22  to engage the bottom of the generator case  11  between the intake and outlet openings. Not shown in  FIG. 5 , the seal may be a soft rubber or rubber-like tubular seal  326  like the seal of  FIG. 24 . Four short angle irons  35  upstanding at the top of the plenum engage corners of the generator case  11  to hold the generator  10  in place. These are best seen in  FIGS. 4 and 5 . Any suitable alternative feature can be used for locating the generator and keeping it in place such as a continuous rim around the bottom of the generator case  11 . Such a rim is shown in  FIG. 26  at  408 , for example. 
         [0041]    In an alternative embodiment of the invention, as shown in  FIG. 6 , a plenum  37  supports the entire toolbox  15 . The interior ducts and the openings  26  and  27  are similar to those described above. Openings  38  and  39  are cut into the bottom wall of the box  15 . These conform generally in size and shape to the openings  19  and  21  of the plenum as shown in  FIG. 2 . In this embodiment as well as in that previously described, within the ducts  23  and  24  suitable soundproofing  25  covers every interior surface. The soundproofing  25  may be a commercially available duct insulation and may afford a degree of heat insulation as well, keeping the box outer surface relatively cool. 
         [0042]    In yet another alternative embodiment as shown in  FIGS. 7 and 8 , the toolbox and plenum are constructed together as a single unit. The toolbox  45  is shown with a lid  46 . The toolbox bottom  48  serves as the bottom wall of the plenum ducts  50  and  51 . The location of the engine-generator set and enclosure is indicated in broken lines at  53 . A rear wall  54  for the box  45  serves also as the back wall of the plenum at  56 . A wall  57  partitions the cool intake air at  50  from the hot gases escaping at  51 . In  FIG. 7 , at  58  can be seen the opening by which air passes from the upper surface of the plenum. Two or more upright generator locating brackets  61  serve to locate the generator and keep it in place. A seal  60  runs along the top of the wall  57  sealing and engaging the bottom of the generator enclosure. As in the boxes of  FIGS. 1-5 , a pair of openings, here  63  and  64 , through the face of the box front wall  65  open into the ducts  50  and  51 , respectively. Soundproofing is visible at  66 . The bend in the wall  57  evident in the wall  22  of  FIG. 2  is seen at  68  in  FIG. 7 . 
         [0043]    It is also envisioned that if the air intake openings, the cooling air outlet opening and the tail pipe of the generator open through a lid, front, back, side wall or bottom of the generator enclosure, a similar plenum will stand upright next to that wall or have a portion thereof standing upright next to the wall and be conformed to supply air into the openings and receive air and exhaust from within the generator enclosure. Again soundproofing is applied to interior duct surfaces. The plenum toolbox combination may simply be positioned in the basement of an RV or in an RV generator compartment to discharge the mixed, quieted discharge in the downward direction for the RV user who cannot put the box in his truck but still wants a quiet, sound-proofed installation. The plenum intake and discharge may be in the downward or underside of the generator enclosure as described below. 
         [0044]      FIGS. 18 and 19  illustrate two alternate arrangements for use of the box and plenum combination of the invention in an RV generator compartment. In  FIG. 18  a box  135  includes a lower plenum  137  that supports the engine-generator set as previously described. A number of mounting flanges  139  secured to sidewalls  140  of the box  135  secure the box  135  in an opening  142  in the floor  144  of the RV generator compartment  150 . 
         [0045]    The lowermost portion of the box  135  that contains the plenum  137  protrudes below the floor  144  of the generator compartment. Cooling air intake opening  148  leads into cooling air intake duct  149 . The duct  149  communicates with the engine-generator set through a pair of openings  152  and  154 , providing combustion and cooling air as previously described. Cooling air exits the environment of the engine-generator set through an opening  156  and an exhaust diffuser  158  as previously described. This diffuser  158  disperses exhaust into the lower temperature cooling air within the air outlet duct  160  for emission through a further opening  162 . 
         [0046]    In an alternative embodiment seen in  FIG. 19 , the box  135 ′ containing the engine-generator set is contained entirely within the RV generator compartment  150 . One or more openings  166  formed in the floor  144  of the compartment  150  provide air intake to the intake duct  149 . That air acts as described in connection with  FIG. 18  to aspirate the engine and cool the generator and engine. Cooling air escapes through the opening  156  into the duct  160  formed in the plenum and out an opening  168  formed in the floor  144  of the generator compartment. Suitable securing means  170  may be provided to retain the box  135 ′ in place within the compartment  150 . 
         [0047]    Gasoline and battery power can be taken from the truck or tow vehicle or can be separately installed in the box  15  of  FIG. 1 . With a separate fuel tank and battery installed in this box, a completely independent power source is provided that can be used at a cabin or, e.g., mountain retreat, but that goes home with the owner, for theft prevention, and for further uses away from the cabin or retreat. In  FIG. 6  the box  15  is equipped with the generator&#39;s off/on switch  31  and/or ignition key switch  32  and/or a RF remote  33  and remotely activated ignition switch  34 . Also mounted are such meters  36 - 38  as may be desired. These typically would include engine hours of use, temperature, oil pressure, amperage, without limitation. The RF remote  33  and RF activated switch  34  are particularly desirable features allowing activation of the generator  10  from within an associated RV, for example. 
         [0048]      FIGS. 9 and 10  illustrate an embodiment of a diffuser providing for good mixing of hot exhaust gas with the cooler, but warm, cooling air exiting the generator through the duct  24 . The diffuser  260  includes an exhaust pipe  261  having linearly arranged openings  263  on opposite sides of the pipe along a length of a pipe extending within the duct  24 . A solid or vented end plate  265  is welded across the end of the pipe  261 . A pair of heat shields  267  and  268  protect the plenum walls and its soundproofing from the heat of the pipe  261  and the escaping exhaust. The diffuser  260  affords good mixing of the exiting cooling air (indicated at  269 ) with the hot exhaust from openings  263  of the pipe  261 , indicated by the unnumbered arrows in  FIG. 10 . A set of welds  270  affix a top heat shield  267  to the pipe  261  and a set of welds  271  affix a lower, larger heat shield  268  to that pipe. 
         [0049]    The diffuser  260  of  FIGS. 9 and 10  is preferable for a relatively shallow duct  24  as depicted in  FIG. 9 . Where greater depth in the duct  24  is available, as depicted in  FIG. 11 , a diffuser  280  as illustrated in  FIGS. 11 and 12  can be used. Like the diffuser of  FIGS. 9 and 10 , the diffuser  280  has an exhaust pipe  281 . A series of holes  283  open from within the pipe  281 . Unlike the diffuser of  FIGS. 9 and 10 , the holes  283  are not arranged in just a single linear array, but open, in this exemplary embodiment, in several directions on each side of the pipe  281  as best seen in  FIG. 12 . The pipe  281  has a closed end  285 . At the closed end  285 , a circular plate  286  extends radially outward from the pipe  281 . Connected with the plate  286  is a cylindrical shell  288  encircling the location of the pipe  281  that has the holes  283 . The plate  286  may close the end of the pipe  281  and the end of the shell  288 . The plate may have openings venting the pipe and shell ends. The cylindrical shell  288  has a series of openings  289  larger than the openings  283  in the pipe  281 . These open out of the shell radially in, for example, four directions on each side of the shell as best seen in  FIG. 12 . Although shown as circular in cross-section, the diffuser of  FIG. 11  can be oval, square, rectangular, etc., in its cross-section. The outer shell  288  provides heat shielding and gives additional mixing of air and exhaust. 
         [0050]    Air that is cooler than the hot exhaust and that is being moved by an engine cooling blower or fan in the generator enclosure is driven into the outer shell  288 . It mixes with hot exhaust and the intermixed air and exhaust exits the shell through the openings  289  at a moderated temperature. Good mixing of the cooler engine cooling air and hot exhaust results, protecting the walls of the duct  24  and its soundproofing. 
         [0051]    An alternative diffuser embodiment and gas flow arrangement appear in  FIGS. 13 and 14 . The diffuser  290  includes an exhaust pipe  292  onto which a head  293  is affixed. Multiple openings  295  in the head emit hot exhaust against the flow of cooler engine cooling air entering the plenum at  296 . The mixed gasses escape downward through an opening  298 . 
         [0052]    Further exemplary diffuser embodiments are shown in  FIGS. 20 ,  21  and  22 . In  FIG. 20  a rolled exhaust dispersion tube  175  is shown. An exhaust connection is diagrammatically indicated at  177  and a series of inward directed holes  179  emit hot exhaust in the directions indicated by the unnumbered arrows. The diffuser  175  of  FIG. 20  is seen from above looking down into the air outlet duct  24 . 
         [0053]    In  FIG. 21  a further, generally U-shaped diffuser  185  is seen, again looking downward into the air outlet duct  24 . An exhaust connection to the diffuser is diagrammatically indicated at  187 . Holes  189  along the length of the diffuser direct hot exhaust in the directions indicated by the unnumbered arrows. 
         [0054]    A side view of the diffuser  185  of  FIG. 21  is illustrated in  FIG. 22 . There the tailpipe  190  of the generator-driving internal combustion engine (not shown) is seen extending through an upper surface of the plenum where a coupling  192 , that may be welded in place, connects the tailpipe  190  to the diffuser  185 . In the case of the diffuser  185  shown in  FIG. 22 , the diffuser is formed from cut and welded sections. Various shapes and configurations, suited to particular installations, can be obtained. 
         [0055]    Use of a diffuser such as the diffusers  260 ,  280 ,  290 ,  175  and  185  results in well-mixed gases escaping the duct  24  without hot spots. In addition, each of the diffusers  60 ,  80 ,  90 ,  175  and  185  converts the typical “putt, putt” exhaust sound to a steady hum. 
         [0056]      FIGS. 15 and 16  illustrate a further embodiment of the combination generator and toolbox. In  FIG. 15  the generator  10  can be seen residing in its own compartment in the toolbox  115 . A gas output duct  117  directs the mixture of exhaust and cooling air directly upward. An opening  119  in the lid  118  of the box  115  aligns with the duct  117 . In a separate compartment  121  a dedicated gas tank  122  is shown in broken lines. Alternatively a smaller tank than that shown may be provided leaving room for a tool area or other storage. Access to the interior of the generator may be had through a removable front panel  124  and aligned service door  125  into the case  11 . Access to the generator is available as well as through the open lid  118  and removable upper cover of the generator case  11 . In one preferred alternative embodiment of this arrangement, the removable panel  124  is affixed to the lid and swings up and away from the generator when the lid is opened. Air intake openings may be through the wall of the box that faces the cab of the truck. In this embodiment, the location of the intake duct openings adds to the quieting provided and the exhaust gasses are expelled upwardly at a high rate of speed, reducing exhaust smells at ground level.  FIG. 16  shows the closed tool box in the back of a pickup truck. The box  118  very much resembles the typical textured sheet metal tool box generally viewed as acceptable in appearance. 
         [0057]    Shown in  FIG. 23 , the embodiment illustrated in  FIGS. 15 and 16  has an air intake opening  301  formed in the right hand side panel  303  of the box  115  as illustrated in  FIG. 23 . Optional screening  305  is shown to keep animals out of the ducts. The box  115  of the particular embodiment is notched on each side as shown at  307  to accommodate the wheel wells of a short bed pickup truck. 
         [0058]    In  FIG. 24  the floor of the tank containment compartment  121  has been removed and the cold air duct  320  can be seen extending below the compartment to an opening  322  that provides engine and generator cooling air to the generator  10  and combustion air to the generator drive engine. The partitioning wall  324  is shown having a pair of parallel seals  326  extending along its upper edge. To the left of the wall  324  in  FIG. 24  is shown the hot air opening  328  that receives warm cooling air from the generator  10  into the duct  330  that extends below the generator  10  to an upright duct portion  332 . 
         [0059]    In  FIG. 24  the optional screening shown covering the duct  330  in  FIG. 24  is broken away and a diffuser  334  is seen having an intake pipe  336  for communication with the tail pipe of the internal combustion engine that drives the generator. Small holes  338  are formed in a series along the diffuser  334 , which in this case is an L-shaped hollow, rectangular in cross section diffuser capped at its end  340 . From the duct  330  intermixed warm cooling air and hot exhaust moves to the upright duct portion  332  and escapes via the opening  119  of  FIG. 16 . 
         [0060]    The embodiment of  FIGS. 15 and 16  are particularly suited for such uses as houseboats, large cabin cruisers and the like where noxious fumes raise the possibility of asphyxiation, particularly when occupants sleep and the generator runs. As shown in  FIG. 17 , an installation of a generator-tool box combination of the kind illustrated in  FIG. 15  on the uppermost deck  128  well above living and sleeping quarters  129 . The upward emission of the exhaust-cooling air mix further moves the carbon monoxide of the exhaust away from the boat inhabitants and where it is most likely to be swept away by the breeze. 
         [0061]    In one further embodiment illustrated in  FIGS. 25 and 26 , cold air is drawn into an enclosure  401  shown in  FIG. 25  with its front cover removed. Cold air is drawn into the enclosure through an opening  403  seen in  FIG. 25 . A duct  404  directs the cold air internally of the enclosure  401  where it is drawn into the cool air supply duct  406  formed below the location for the generator defined by the supporting rim  408 . As previously, the cool air is drawn in to the engine-generator set for cooling and aspiration. Warmed cooling air is expelled into a warm air duct  410  below the generator where it is admixed with hot exhaust as previously. The mix of hot exhaust and warm air travels from the duct  410  to an upright duct  412  seen in  FIG. 25  and escapes through an opening  414  in a sidewall  416  of the enclosure  401 . 
         [0062]    The foregoing descriptions of at least one preferred embodiment are exemplary and not intended to limit the claimed invention. Obvious modifications that do not depart from the spirit and scope of the invention as claimed will be apparent to those skilled in the art. The toolbox containing a generator can afford portability by being movable from one truck to another. Also the generator is easily accessible for repairs. In one embodiment, the toolbox is detachable from the generator and support plenum so as to lift away from the generator and enable access to the generator for repairs. Further, with appropriate hinging, the toolbox lid can be opened sufficiently to permit the generator to be lifted free of the box for major repairs or simply for movement to a new site. Where the toolbox and the generator support plenum are built as a single unit as in the exemplary embodiment of  FIGS. 7 and 8 , the box-plenum combination can be sold shipped as a unit. On the other hand, where the user already has a toolbox, the separate plenum in or under the toolbox can be provided more economically than the provision of a combined box and plenum.