Abstract:
A serviceable draw and return tube assembly for use in fuel tanks is disclosed. The assembly may include a draw tube and a return tube secured to a plate, wherein the plate may be removably secured to a flange, which is fixedly secured to a fuel tank. The process of removably securing the plate to the flange allows for use of different sizes and materials to be utilized in manufacture of the assembly, thereby saving installation time and manufacturing costs.

Description:
[0001]    This application claims priority on a US provisional patent application filed on Oct. 24, 2012, and assigned Ser. No. 61/718,006, in the name of inventors Ken Watson, Evan Waymire, and John Loffink. 
     
    
     TECHNICAL FIELD 
       [0002]    The present invention relates to a servicable draw and return tube assembly, and a process of manufacturing the same, for use in commercial vehicles, and more particularly, to a removable draw and return tube assembly for use in commercial vehicles wherein the draw and return tubes may be removed from a fuel tank after installation therein. 
       BACKGROUND OF THE INVENTION 
       [0003]    The present invention is particularly intended for use on commercial vehicles, although it may be used with any internal combustion engine connected to a fuel tank having a draw and return tube assembly. In particular, diesel engines typically operate by drawing fuel from a fuel tank, combusting a portion of the fuel and then returning the unused, or uncombusted, fuel to the fuel tank. The volume of fuel returned to the fuel tank is dependent on engine power output, and generally is quite substantial. Accordingly, such draw and return tube assemblies play a vital role in the operation of diesel engines. 
         [0004]    Heavy commercial vehicles frequently employ dual fuel tanks, also called saddle tanks, wherein fuel is drawn simultaneously from both tanks for combustion within the engine. To prevent uneven draw and return of the fuel, which may lead to air being drawn into the engine, fuel flow regulators, such as draw and return tube assemblies, typically are installed in each of the dual fuel tanks. 
         [0005]    One prior art draw and return tube assembly comprises draw and return tubes fixedly connected to a flange at one end of the tubes. The flange typically is fixedly mounted at an aperture sized to receive the flange on an outside surface of the fuel tank such that the opposite end of each of the draw and return tubes extends downwardly into fuel held within the lower portion of the tank. Draw and return lines from the engine are connected to the draw and return tubes at the flange, outside the tank. 
         [0006]    The tube end openings inside the tank and opposite the flange typically extend away from one another and are each positioned an equal distance from the flange so that the draw and return tube fuel openings are also each positioned an equal distance below the top surface of fuel held within the tank. In this arrangement, when the two saddle tanks and the corresponding draw and return tube assemblies are each positioned on the commercial vehicle, the pressure head of fuel positioned above the draw and return tube openings of each assembly will result in equal amounts of fuel being withdraw from each of the tanks and equal amounts of fuel being returned to each of the tanks. In addition, swedging or crimping of the end of the return tube opening opposite the flange will facilitate filling the return fuel line. This filling of the return fuel line enables a siphon effect between the left and right hand fuel tanks. Accordingly, the draw and return tube assemblies of the prior art act as passive flow regulators for ensuring equal levels of fuel drawn and returned to each of the two saddle fuel tanks. 
         [0007]    Conventional draw and return tubes are fixedly secured to a flange that is fixedly secured, such as by welding, to the fuel tank. If servicing issues arise with respect to an interior surface of the fuel tank, or with the draw and return tubes themselves, the entire tank may need to be removed and a new tank installed on the truck. This results in expensive and time consuming servicing operations. 
         [0008]    Accordingly, there is a need for a draw and return tube assembly that may be serviceable, i.e., removable from a fuel tank, such that an interior of the fuel tank, and the draw and return tubes themselves, may be accessible during servicing of a fuel tank and a draw and return tube assembly after installation thereof. 
       SUMMARY OF THE INVENTION 
       [0009]    The present invention provides a servicable draw and return tube assembly, and a process of manufacturing the same, that overcomes the disadvantages of the prior art. One aspect of the present invention provides a draw and return tube assembly which may be removably secured to a flange, wherein the flange may be fixedly secured to a fuel tank. Removably securing the draw and return tube assembly to the flange may avoid a costly and time consuming welding step, and may allow components of the draw and return tube assembly to be manufactured of a size and with materials that need not withstand a heat intensive welding step. Accordingly, the serviceable draw and return tube assembly may be manufactured at a lower cost than prior art devices and may also allow servicing of the fuel tank and the draw and return tube assembly unit itself, and other components such as a fuel sending unit, after installation thereof. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]      FIG. 1  is a top view of a flange to which a serviceable draw and return tube assembly may be removably secured. 
           [0011]      FIG. 2  is a side view of the flange of  FIG. 1 . 
           [0012]      FIG. 3  is an end view of a serviceable draw and return tube assembly. 
           [0013]      FIG. 4  is a side view of the assembly of  FIG. 3 . 
           [0014]      FIG. 5  is a top view of the assembly of  FIG. 3 . 
           [0015]      FIG. 6  is a top view of a plate of a serviceable draw and return tube assembly. 
           [0016]      FIG. 7  is a cross sectional side view of the plate of  FIG. 6  taken along line E-E of  FIG. 6 . 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0017]    The invention discloses a draw and return tube assembly that is intended for use on commercial vehicles, although it may be used with any internal combustion engine connected to a fuel tank utilizing a draw and return tube assembly. 
         [0018]      FIG. 1  is a top view of a flange  10  to which a serviceable draw and return tube assembly  12  ( FIG. 3 ) may be removably secured. Flange  10  may be fixedly secured to a fuel tank  14  such as by a weld  16  or other securement structure. This weld step may take place before a serviceable draw and return tube assembly may be secure to flange  10 . Weld  16  generally will extend completely around a perimeter  18  of flange  10  so as to define an air tight and a liquid tight seal between tank  14  and flange  10 . Only a portion of weld  16  is shown in this view of ease of illustration. In the embodiment shown, flange  10  defines a central aperture  20  that extends completely through flange  10  and defines a diameter  22  of 3.587 inches (in). Positioned around central aperture  20  is an arrangement of securement apertures  24 , arranged in a circle  26  that defines a diameter  28  of 4.114 in. Securement apertures may be internally threaded and may be arranged so as to receive fasteners to secure a serviceable draw and return tube assembly  12  ( FIG. 3 ) thereto. In the embodiment shown, flange  10  includes  10  securement apertures  24 , but in other embodiments, other arrangements and numbers of securement apertures, or other securement means, may be utilized. 
         [0019]      FIG. 2  is a side view of the flange  10  of  FIG. 1 . In this embodiment flange  10  includes a central, generally flat region  30  which includes central aperture  20  and which defines a diameter  30  of 4.65 in. An outer region  32  of flange  32  defines an angle  34  with respect to flat region  30  of flange  10 . In particular, in the embodiment shown, outer region  32  defines a curvature having a radius  36  of 11.02 in, which may mate with an outer surface of fuel tank  14 . Fuel tank  14  may include an aperture aligned with central aperture  20  such that a serviceable draw and return tube assembly  12  ( FIG. 3 ) positioned within central aperture  20  will also be placed through an aperture in fuel tank  14  and into and interior  36  of the fuel tank. 
         [0020]      FIG. 3  is an end view of a serviceable draw and return tube assembly  12 . In this embodiment, assembly  12  includes a flat, circular plate  40  that defines an arrangement of securement apertures  42  that may correspond in placement to securement apertures  24  of flange  10 . Fasteners  44 , such as threaded screws or bolts may be utilized to secure plate  40  to flange  10 . In an embodiment wherein the securement apertures  24  of flange  10  ( FIG. 1 ) are not internally threaded, fasteners  44  may comprise self tapping fasteners or the like. A seal  46 , such as a washer shaped cork gasket, only a portion thereof shown for ease of illustration, may be positioned between flange  10  and plate  40  to ensure an air tight and a liquid tight seal there between. 
         [0021]    Plate  40  may further include first and second tube apertures  48  and  50  for securement of a draw tube  52  and a return tube  54 , respectively, therein. Plate  40  may further include a third aperture  56  extending there through for securement of a vent device therein, and a fourth aperture  58  extending there through for securement of a fuel sending unit therein, for example. Fourth aperture  58  may include an arrangement of five securement apertures  60  extending there around for removable securement of a fuel sending unit thereto. First, second, third and fourth apertures  48 ,  50 ,  56  and  58 , and securement apertures  60 , normally will all be positioned within an interior radial position of plate  40  such that components secured within these apertures will extend through, and not interfere with, central aperture  20  of flange  10  or an aperture in fuel tank  14 . In another embodiment a fuel sending unit may be fixedly secured to plate  40  or a fuel sending unit may be manufactured as an integral component of plate  40 . In still other embodiments, other apertures or other types of securement structures may be positioned within or on plate  40  for securing other structures, such as one or more auxiliary fuel draw tubes for use with truck mounted auxiliary fuel fired heaters, generators, refrigeration units, and the like. 
         [0022]      FIGS. 4 and 5  are a side view and a top view, respectively, of the assembly  12  of  FIG. 3 . Assembly  12  further includes a stabilizing bracket  62  that may be secured to an underside  64  of plate  40  and which may include two apertures  66  through which draw and return tubes  52  and  54  extend. A stabilizing bracket may be utilized in such a serviceable draw and return tube assembly  12  because, due to the removable connection between plate  40  and flange  10 , instead of prior art securement mechanisms such as welding, tubes  52  and  54  may be manufactured with a thinner tube wall thickness than previously utilized. In other words, because tubes  52  and  54  need not withstand the harsh environment of a welding step, thinner walled tubing may be utilized, which may warrant use of stabilizing bracket  62 . Due to the removable connection between plate  40  and flange  10 , instead of prior art securement mechanisms such as welding, tubes  52  and  54  may be secured to connectors  68  and  70  on plate  40  by an adhesive  72 , instead of a welding step, and connectors  68  and  70  may include on a top side  74  of plate  40  a single external lip  76  for connection to fuel hoses by use of a quick disconnect attachment. Moreover, due to the elimination of the welding step of a plate to a flange, molded plastic draw and return tubes  52  and  54  may be utilized, instead of the prior art requirement of rigid metal tubing. In an embodiment wherein tubes  52  and  54  are manufactured of a plastic material, the plastic tubes may be connected to connectors  68  and  70  by integral barbed fittings, or connectors  68  and  70  may themselves be barbed fittings which may allow attachment of tubes  52  and  54  thereto, as well as attachment of fuel hoses thereto on an opposite side of plate  40 . In such an embodiment, adhesive may not be utilized to secure the tubes  52  and  54  to the connectors  68  and  70 . Similarly, due to the elimination of the welding step of a plate to a flange, an plastic securement device, such as an adhesive or a zip tie  78 , may be utilized at a lower end region of draw and return tubes  52  and  54 , at which the tubes cross one another, to secure the tubes against movement during operation of the vehicle to which the assembly  12  is installed. 
         [0023]      FIG. 6  is a top view of a plate of a serviceable draw and return tube assembly. 
         [0024]      FIG. 7  is a cross sectional side view of the plate of  FIG. 6  taken along line E-E of  FIG. 6 . In  FIG. 7 , connectors  68  and  70  are shown including a barbed fitting to which a plastic tube, such as draw tube  52 , may be secured by a simple press or snap fit operation, i.e., the tube is pushed into engagement with barbs  80  of connectors  68  or  70 . Plate  40  may be manufactured of a sturdy material such as a metal, including steel or aluminum, for example, or of a rigid plastic or composite material. Use of barbed fittings for connectors  68  and  70  allows for the quick connection of plastic tubes, which are relatively inexpensive to manufacture. Moreover, the quick connect barbed fitting, which allows for a simple press or snap fit of the plastic tubes on the barbs  80 , decreases the manufacturing time for fully assembling serviceable draw and return tube assembly  12  Moreover, use of barbs  80  on connectors  68  and  70  may eliminate the need for welding tubes  52  and  54  to plate  40 , thereby eliminating the need for providing a thickness of material of plate  40  and connectors  68  and  70  that can withstand the harsh temperatures and environment of a welding operation. Accordingly, plate  40  and connectors  68  and  70  may be manufactured with a relatively thin thickness of material, compared to prior art assemblies, thereby saving material costs in the manufacture of assembly  12 . Barbed connectors  68  and  70  also allow for simple changing of tubes  54  and/or  52  during servicing if the need arises. 
         [0025]    Still referring to  FIG. 7 , external lips  76  of connectors  68  and  70  allow for a quick connect press or snap fit of a fuel hose to external lips  76  of connectors  68  and  70 , opposite plate  40  from barbed connections  80 . Such a press or snap fit external lip design, wherein a hose is connected to external lips  76 , may eliminate the need for a thickness of metal at connectors  68  and  70 , which may be required in a design when a threaded connection is utilized to secure a fuel hose to plate  40  opposite from barbed connections  80 . 
         [0026]    In the above description numerous details have been set forth in order to provide a more through understanding of the present invention. It will be obvious, however, to one skilled in the art that the present invention may be practiced using other equivalent designs.