Abstract:
A fuel cylinder for use in fueling vapor-powered machines and devices is claimed. The fuel cylinder contains a fuel vapor withdrawal pipe that bends upward towards the top edge of the cylinder when the cylinder is in its position of use, for example, the horizontal position if the tank is used horizontally. A liquid splash guard surrounds the inlet of the fuel vapor withdrawal pipe to protect the inlet from splashing of liquid propane in the cylinder. A brace connects to the fuel vapor withdrawal pipe to stabilize the fuel pipe during high vibration use. In one embodiment, the splash guard and brace are welded to the internal surface of a joggle in the rim of the upper head portion of the cylinder before the upper head portion and lower head portion of the cylinder are mated and welded together.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates generally to the field of pressurized fuel cylinders, and more particularly to means for preventing splashing of liquid into the vapor withdrawal pipe and for stabilizing the pipe. 
       BACKGROUND OF THE INVENTION 
       [0002]    Propane gas is becoming known as an attractive alternative to the use of conventional gasoline to fuel lawnmowers and other devices. Using propane tanks for lawnmowers eliminates the spillage associated with gasoline use and lessens harmful vapor releases. Propane versions of lawnmowers have been found to significantly reduce ozone-destroying emissions. 
         [0003]    Propane gas cylinders or tanks are generally made from lightweight metals such as aluminum, but may also be made of steel or composite material. Because the cylinders are typically laid on their sides when positioned on the lawnmower, a pipe, runs from the service valve coupling at the top of the cylinder into the interior of the cylinder, and has a bend formed in it to position the open end of the pipe adjacent to the side of the cylinder at or near its uppermost point. This allows the propane vapor enter the pipe and exit through the service valve. 
         [0004]    A significant problem exists in conventional gas cylinders with internal pipes for withdrawing liquid or gas, in that, due to the long lever arm presented by the pipe, vibrations of the pipe can result in significant stresses on the connection of the pipe to the service valve coupling. As a result, the pipe can develop fatigue cracks at the point where it is internally threaded into the service valve coupling. It would be desirable to have at least one brace inside the tank to support the vapor withdrawal pipe to prevent breaking of the pipe, especially in a vibration-prone environment. 
         [0005]    In addition, because the bottom portion of the tank contains liquid fuel, it is important that means be employed to reduce the possibility that liquid fuel splashes into the vapor withdrawal pipe. In prior art uses of horizontal propane tanks in other vehicles, such as in recreational vehicles, the possibility of propane splashes is lessened by the fact that the vehicle is not generally in motion when the propane tank is in use. When horizontal propane tanks are used to fuel moving vehicles, such as lawnmowers, however, the tanks can be expected to operate in uneven or rough terrain in which sloshing and splashing of propane into the vapor withdrawal pipe could be a problem. It would therefore be desirable to have a means for reducing the possibility of splashing liquid entering into the vapor withdrawal pipe of a horizontal propane tank. 
         [0006]    U.S. Pat. No. 5,105,996 (“the &#39;996 patent”) addresses the problem of providing support for a liquid propane fuel pipe inside a horizontal propane cylinder. This prior art invention employs a cylinder made from a top section including a “joggle lip” which mates with the substantially straight rim lip of the cylinder bottom section. A brace member is welded to the joggle. The brace member includes a pair of spaced tines which are spaced apart to allow the liquid pipe to be fitted between the tines. The liquid pipe is secured to the brace prior to assembly of the top and bottom cylinder sections by fitting the pipe between the tines and then crimping the tines together to clamp the pipe in the brace. Once the pipe is secured within the brace, the top and bottom head sections are welded together to form the cylinder. The invention disclosed in the &#39;996 patent thus addresses the problem of providing bracing for a liquid propane fuel pipe, but does not address the problems peculiar to the use of a horizontal propane tank with an internal vapor fuel pipe put to use in an operating environment which would cause splashing of liquid fuel. Further, the &#39;996 patent does not address the need to protect the inlet of the vapor fuel pipe from splashing of liquid propane. 
       SUMMARY OF THE INVENTION 
       [0007]    It is an object of the present invention to provide a pressurized fuel cylinder for supplying fuel vapor to devices that may be operating in rough terrain and therefore be subjected to substantial jolts and vibrations. 
         [0008]    It is another object of the present invention to provide a support apparatus for the vapor fuel withdrawal pipe of a fuel cylinder. 
         [0009]    It is yet another object of the present invention to provide a means for reducing the possibility of liquid fuel splashing into the vapor fuel withdrawal pipe inlet. 
         [0010]    The present invention achieves these objectives by providing a fuel cylinder with a vapor fuel withdrawal pipe that is supported in one or more places by internal bracing and in which a liquid splash guard protects the inlet of the vapor fuel withdrawal pipe from splashing fuel. 
         [0011]    For purposes of summarizing the invention, certain aspects, advantages, and novel features of the invention have been described herein. It is to be understood that not necessarily all such advantages may be achieved in accordance with any one particular embodiment of the invention. Thus, the invention may be embodied or carried out in a manner that achieves or optimizes one advantage or group of advantages as taught herein without necessarily achieving other advantages as may be taught or suggested herein. 
         [0012]    These and other embodiments of the present invention will also become readily apparent to those skilled in the art from the following detailed description of the embodiments having reference to the attached figures, the invention not being limited to any particular embodiment(s) disclosed. 
     
     
       DESCRIPTION OF THE DRAWINGS 
         [0013]      FIG. 1  is a frontal, partially broken-away view of a gas cylinder employing a brace and splash guard in accordance with one embodiment of the present invention. 
           [0014]      FIG. 2  is a cross-sectional view of the cylinder of  FIG. 1 , taken along line  2 - 2  of  FIG. 1 , showing a top view of the brace securing the vapor fuel pipe and the splash guard. 
           [0015]      FIG. 3  is a cross-sectional view of one embodiment of the invention taken along line  3 - 3  of  FIG. 2 , showing the weld joints securing the brace to the top head joggle lip. 
           [0016]      FIG. 4  is a partial perspective view of one embodiment of the top head section showing the vapor fuel pipe, the brace, and the splash guard. 
           [0017]      FIG. 5  is a partial broken-away view of one embodiment of the brace, showing the brace tines in further detail. 
           [0018]      FIG. 6  is a front view of one embodiment of the splash guard, before it is welded into place. 
       
    
    
       [0019]    Repeat use of reference characters throughout the present specification and appended drawings is intended to represent the same or analogous features or elements of the invention. 
       DETAILED DESCRIPTION 
       [0020]    The present invention and its advantages are best understood by referring to the drawings. The elements of the drawings are not necessarily to scale, emphasis instead being placed upon clearly illustrating the principles of the invention. 
         [0021]      FIG. 1  illustrates one embodiment of a horizontal fuel gas cylinder  10  that may be used on a propane-powered lawnmower or other gas fuel-powered device. The cylinder  10  is made up of a “top” head section  11  and a “bottom” head section  12 , which sections are secured together by a circumferential weld joint  13  to form a pressure vessel for containing fuel. (Note that the use of “top” and “bottom” head sections refers to the positioning of the cylinder in its traditional orientation, which is the orientation used for filling the cylinder, and not in its horizontal position, i.e., the position of its use.) Both the top head and the bottom head sections may be fabricated from aluminum or aluminum alloy to minimize the weight of the cylinder and to resist corrosion, though other materials could be used as well, such as steel or composite materials. In this embodiment, a guard or collar  14  is welded to the top head  11  in the conventional manner, and a foot ring  15  is welded to the bottom of the bottom head section  12 . 
         [0022]    In another embodiment of the invention, the cylinder is made of a composite material. In the composite embodiment, the head sections are connected together with adhesive. 
         [0023]    Referring to  FIG. 1 , the cylinder  10  also comprises a pipe  16  contained within the cylinder  10 . The pipe  16  is made of steel in one embodiment, though other materials could be employed, such as aluminum or plastic. In one embodiment, the pipe  16  is a ⅜ inch steel NPS pipe. One end  17  of the pipe  16  is threaded into a coupler  18  which in turn connects to a service valve  19 . The valve  19  can be used to connect to an engine to provide the fuel vapor for engine operation. The pipe  16  has a bend  20  formed in it to bring the pipe&#39;s “open” end  21  adjacent to the side  22  of the bottom head section  12 . In operation, the cylinder  10  is laid horizontally on its side as shown in  FIG. 1 , and oriented so that the pipe end  21  is at or near the uppermost point in the cylinder  10 . 
         [0024]    In the conventional manner, the cylinder  10  further includes additional fittings, such as a fill valve, a fill coupling, a float valve to indicate the fuel level and a pressure relief valve. These additional fittings are not illustrated herein. 
         [0025]    To relieve the strain on the pipe  16  due to its long lever arm and the vibration experienced during operation of the lawnmower, a brace  30  is included to secure the pipe in accordance with the present invention. For aluminum cylinders, the brace  30  may be made of ⅛ inch thick aluminum, and in one embodiment is made of 6061-T6 aluminum alloy. As illustrated in  FIG. 2 , one embodiment of the brace  30  defines two protruding tines  36  and  38 , which are spaced apart by a sufficient distance (prior to assembly with the pipe  16 ) to just allow the pipe  16  to be fitted between the tines. It is desirable to provide a slot dimension between the tines which is only slightly larger than the outer dimension of the pipe  16 , so that the pipe fits tightly between the tines. This facilitates the clamping of the pipe tightly between the tines, so that the tine compression or crimping is not required to do all the work of securing the pipe in place. 
         [0026]    As is better illustrated in  FIG. 3 , in one embodiment a joggle  31  is formed in the top head  11 , and the bottom head  12  is formed with a straight rim  33 . This arrangement permits the brace  30  to be welded to the joggle  31  of the top head  11  prior to the mating of the top and bottom head sections  11  and  12 . The pipe  16  can then be fitted between the tines  36  and  38  of the brace  30  prior to assembling the top and bottom heads  11  and  12 , and the tines squeezed together to secure the pipe  16  in place, as illustrated in  FIGS. 2 ,  4  and  5 . It will be appreciated that the tines  36  and  38  permit mechanical engagement with the pipe  16  by crimping the tines together into contact with the pipe. In this embodiment, because the brace is typically aluminum, and the pipe is steel, welding the brace  30  to the pipe  16  would be difficult due to the dissimilar materials. 
         [0027]    As illustrated in  FIG. 3 , the brace  30  is welded to the joggle  31  of the top head section  11  via weld  32 . In one embodiment illustrated herein, the brace  30  is welded to the joggle  31  by gas tungsten arc welding. For an aluminum cylinder of one embodiment, the welding filler wire found particularly well suited to the purpose for welding the 6061-T6 aluminum brace  30  to the joggle of 5154 aluminum is 4043 aluminum alloy filler wire. This particular filler wire is compatible with the two aluminum alloys, the 6061-T6 and the 5154, yet is a ductile material which provides a strong bond between the brace and the joggle. It is important that good welding techniques be employed to weld the brace to the joggle, such as welding to the ends of the brace and having an ample supply of the filler wire, so that the weld joint is not starved for filler during the welding process, and allowing the weld to spill over slightly at the brace ends. Such good welding techniques should be employed to prevent cracking of the weld due to the vibration experienced during operation of the lawnmower or other device. 
         [0028]    Advantages of the brace  30  described above include the securing of the pipe  16  against vibration, thereby reducing the stress on the pipe and reducing stress failure rates, while fulfilling the requirement (applicable to metal cylinders) that no welding can be done to the straight sides of the cylinder. Further, the brace secures the pipe in a rugged and inexpensive manner even when the pipe and the brace are of dissimilar materials which cannot readily be welded together. While the brace disclosed herein is clamped onto the pipe by crimping the tines, and such method is particularly advantageous because of its simplicity, low cost and ruggedness, other mechanical means of connecting the brace to the pipe could alternatively be employed, such as inserting the pipe through a hole in the brace element. In embodiments of the invention in which the cylinder is fabricated from composite materials, the brace is glued to the inner surface of the cylinder rather than welded. 
         [0029]    As illustrated in  FIGS. 1 ,  2 , and  4 , the cylinder  10  includes splash guard  40 , which is attached to the interior surface of joggle  31  of the top head section  11  as shown in  FIGS. 2 and 4 . The attachment of the splash guard, accomplished for metal cylinders by welding of the splash guard  40  to the joggle  31  of the top head  11 , takes place prior to the mating of the top and bottom head sections  11  and  12 . In one embodiment, the splash guard  40 , further illustrated in  FIG. 6 , is a roughly rectangular or oblong aluminum sheet  44  containing aperture  41 . Although the aperature is illustrated in  FIG. 6  as a round hole, other shapes of apertures, such as oval or slotted, are also within the scope of the present invention. Further, other shapes of splash guards, such as circular or oval, are possible without departing from the scope of the present invention. 
         [0030]    In the embodiment illustrated in  FIG. 2 , the sheet  44  is bent or curved as shown and fitted over the pipe  16  in such a manner that the pipe  16  is fed through the aperture  41  of the splash guard  40 . In one embodiment, the splash guard  40  is welded to the joggle  31  via two welds  42  at the distal ends of the splash guard  40 . In composite cylinders, the splash guard is attached to the interior surface of the cylinder via adhesive. 
         [0031]    After the brace  30 , pipe  16  and splash guard  40  are installed to the top head section  11 , as described herein, the top head section  11  is mated to the bottom section  12  in the conventional manner. In one embodiment, the completed fuel cylinder is approximately one foot in inside diameter by about twenty-eight (28) inches in length. 
         [0032]    Although the illustrated embodiment is a fuel cylinder designed for horizontal use, other orientations and shapes of fuel tanks could also employ the present invention, provided that the tanks have a fuel vapor withdrawal pipe internal to the cylinder. 
         [0033]    This invention may be provided in other specific forms and embodiments without departing from the essential characteristics as described herein. The embodiment described is to be considered in all aspects as illustrative only and not restrictive in any manner. 
         [0034]    As described above and shown in the associated drawings and exhibits, the present invention comprises an improved pressurized fuel cylinder. While particular embodiments of the invention have been described, it will be understood, however, that the invention is not limited thereto, since modifications may be made by those skilled in the art, particularly in light of the foregoing teachings. It is, therefore, contemplated by the appended claims to cover any such modifications that incorporate those features or those improvements that embody the spirit and scope of the present invention.