Patent Publication Number: US-2018037105-A1

Title: Reinforced fuel tank

Description:
BACKGROUND/SUMMARY 
     In vehicle fuel tanks, a section of the top and bottom of the fuel tank may be joined to form an indented shape, referred to as a flower pot. This connected structure provides reinforcement to the fuel tank in selected regions. Reinforcing tank structures may be particularly beneficial in fuel tanks having complex shapes and experiencing high pressures. However, the indented structure can fatigue overtime when it is not formed to precise specifications. Additionally, liquid originating from other engine components, systems, the external environment, etc., may accumulate in the external cavity formed by the contour of the indentation. The accumulated liquid may contain water as well as corrosive fluids that can degrade the fuel tank housing. As such, indented fuel tank reinforcing structures have several drawbacks. 
     To address at least some of the aforementioned problems, a fuel tank is provided. The fuel tank includes a housing enclosing a fuel, the housing including a reinforcement region having two opposing interior surfaces in face sharing contact with one another and a mechanical fastener extending through the reinforcement region, the mechanical fastener including a first head positioned within an external depression of the reinforcement region. The mechanical fastener acts to decrease stress on the joined region, thereby increasing the structural integrity of the fuel tank. As such, the fuel tank&#39;s durability is increased and the likelihood of fuel tank deformation is decreased. 
     The above advantages and other advantages, and features of the present description will be readily apparent from the following Detailed Description when taken alone or in connection with the accompanying drawings. 
     It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a schematic depiction of an engine with a fuel delivery system; 
         FIG. 2  shows an illustration of a fuel tank included in the fuel delivery system shown in  FIG. 1 ; 
         FIG. 3  shows a cross-sectional view of the fuel tank depicted in  FIG. 2 ; 
         FIG. 4  shows an expanded view of a portion of the fuel tank cross-section shown in  FIG. 3 ; 
         FIG. 5  shows another example of a mechanical fastener in the fuel tank; 
         FIG. 6  shows an illustration of another fuel tank included in the fuel delivery system shown in  FIG. 1 ; and 
         FIG. 7  shows another cross-sectional view of the fuel tank depicted in  FIG. 2 . 
     
    
    
     DETAILED DESCRIPTION 
     A fuel tank with increased support of a selected region, referred to as a reinforcement region, and a drainage feature for an external depression caused by the contour of the reinforcement region is discussed herein. The improved tank reinforcement and drainage features are achieved by placing a mechanical fastener, such as a rivet, through a reinforcement region where two opposing sections of a housing of the fuel tank are in contact with one another. The mechanical fastener acts to strengthen the reinforcement region, thereby increasing the fuel tank&#39;s durability and longevity and decreasing the likelihood of fuel tank deformation. Washer plates may be provided between the mechanical fastener and external surfaces of the reinforcement region to more evenly distribute loads on the fuel tank housing from the mechanical fastener. Thus, the washer plates provide greater load dispersion, further improving the structural integrity of the fuel tank. Additionally, in one example the mechanical fastener may include a drain channel enabling liquid accumulated in the external depression in the fuel tank housing to flow through the mechanical fastener and drain away from the tank to avoid excessive liquid accumulation in external regions of the fuel tank. In this way, the mechanical fastener can provide both the function of a reinforcing the tank&#39;s housing but also act a drain for external recesses in the fuel tank, which can be particularly advantageous in mobile road vehicles where water may accumulate even on top surfaces (with respect to ground/gravity) as water can splash up and/or leak into the region of the recess from above. Additionally, the mechanical fastener drain decreases the likelihood of fuel tank housing corrosion caused by accumulated liquids (e.g., water, oil, etc.,) in the external indentation in the fuel tank.  FIG. 1  shows a schematic depiction of an engine and fuel delivery system,  FIGS. 2-4  shows different views of a fuel tank included in the fuel delivery system shown in  FIG. 1  with a reinforcement region with a mechanical fastener extending therethrough.  FIG. 5  shows another example of a mechanical fastener in the fuel tank housing.  FIG. 6  shows another exemplary fuel tank with a mechanical fastener and reinforcement region.  FIG. 7  shows another cross-section of the fuel tank depicted in  FIG. 2 . 
       FIG. 1  shows a schematic depiction of an internal combustion engine  10  in a vehicle  12  with at least one cylinder  14  and is controlled by an electronic engine controller  100 . In the depicted example, the vehicle  12  is a wheeled road vehicle including wheels  13  in contact with a road  15 . However, other types of vehicles other than wheeled vehicles have been contemplated. Additionally, in the depicted example the road  15  is substantially flat. However it will be appreciated that the vehicle may travel over roads or other surfaces having any type of conceivable profile. Engine  10  includes the cylinder  14  with a piston (not shown) positioned therein and connected to a crankshaft (not shown). 
     A fuel delivery system  20  configured to provide metered fuel at desired time intervals to the cylinder  14  is included in the vehicle  12 . The fuel delivery system  20  includes a fuel tank  22  configured to store fuel (e.g., gasoline, diesel, alcohol, combinations thereof, etc.) The fuel tank  22  is schematically depicted in  FIG. 1 . However, it will be appreciated that the fuel tank  22  has greater complexity that is discussed in greater detail herein. The fuel delivery system  20  also includes a fuel pump  24 . In the depicted example, the fuel pump  24  is enclosed in the fuel tank  22 . It will be appreciated that in other examples the fuel pump  24  may be positioned external to the fuel tank  22 . Further in some examples, additional fuel pumps may be included in the fuel delivery system  20 . For instance, the fuel delivery system  20  may include a lift pump and a higher pressure fuel pump. However numerous fuel delivery system pump arrangements have been contemplated. The fuel delivery system  20  also includes a fuel line  26  coupling the fuel tank  22  to a fuel injector  28 . The fuel injector  28  is shown coupled to the cylinder  14 . Additionally or alternatively a port injector may be included in the engine  10 . The fuel delivery system  20  can include additional components that are not depicted in  FIG. 1  such as check valves, a fuel rail, a return line, etc. 
     During operation, each cylinder within engine  10  typically undergoes a four-stroke cycle: the cycle includes an intake stroke, compression stroke, expansion stroke, and exhaust stroke. During the intake stroke, generally, an exhaust valve  30  closes and intake valve  32  opens. Air is introduced into the cylinder  14  via an intake conduit  34  (e.g., intake manifold), and the piston moves to the bottom of the cylinder to increase the volume within cylinder  14 . The position at which piston is near the bottom of the cylinder and at the end of its stroke (e.g., when cylinder is at its largest volume) is typically referred to by those of skill in the art as bottom dead center (BDC). During the compression stroke, the intake valve  32  and the exhaust valve  30  are closed. The piston moves toward the cylinder head to compress the air within the cylinder  14 . The point at which the piston is at the end of its stroke and closest to the cylinder head (e.g., when cylinder  14  is at its smallest volume) is typically referred to by those of skill in the art as top dead center (TDC). In a process hereinafter referred to as injection, fuel is introduced into the cylinder. In a process hereinafter referred to as ignition, the injected fuel is ignited by known ignition means such as a spark plug or compression, resulting in combustion. During the expansion stroke, the expanding gases push the piston back to BDC. The crankshaft converts piston movement into a rotational torque of the rotary shaft. Finally, during the exhaust stroke, the exhaust valve  30  opens to release the combusted air-fuel mixture to exhaust conduit  36  (e.g., exhaust manifold) and the piston returns to TDC. Note that the above is shown merely as an example, and that intake and exhaust valve opening and/or closing timings may vary, such as to provide positive or negative valve overlap, late intake valve closing, or various other examples. Further, the engine may be a compression ignition engine configured to operate with diesel fuel, for example, and thus during operation ignition via spark plug may be dispensed with. 
     The engine  10  also includes a throttle  38  configured to adjust the amount of air provided to the cylinder  14  through the intake conduit  34  via the intake valve  32 . The engine also includes an emission control device  40  positioned downstream of the exhaust valve  30  in the exhaust conduit  36 . Additional components may be included in the engine  10  such as additional conduits, a compressor, an intake manifold, etc., that assist in providing intake air to the cylinder and/or provide other useful functions such as providing boost, cooling, etc. 
     Controller  100  is shown in  FIG. 1  as a conventional microcomputer including: microprocessor unit  102 , input/output ports  104 , read-only memory  106 , random access memory  108 , keep alive memory  110 , and a conventional data bus. Controller  100  is shown receiving various signals from sensors coupled to engine  10 , in addition to those signals previously discussed, including: engine coolant temperature (ECT) from temperature sensor  112  coupled to a cooling sleeve, a position sensor  134  coupled to an accelerator pedal  130  for sensing force applied by foot  132 ; a measurement of engine manifold pressure (MAP) from pressure sensor  122  coupled to the intake conduit  34 ; an engine position sensor from a Hall effect sensor (not shown) sensing crankshaft position; and a measurement of throttle position from sensor  123 . Barometric pressure may also be sensed (sensor not shown) for processing by controller  100 . Controller  100  may also receive signals from sensors located in the engine  10  such as exhaust gas composition sensor  140 , temperature sensor  142 , catalyst bed sensor  144  configured to determine catalyst oxidation, and/or airflow sensor  146 . The controller  100  may also be configured to trigger one or more actuators in the engine  10  and specifically the fuel delivery system  20 . For instance, the controller  100  may be configured to adjust the throttle  38 , fuel injector  28 , fuel pump  24 , etc. Therefore, the controller  100  receives signals from the various sensors of  FIG. 1  and employs the various actuators of  FIG. 1  to adjust engine operation based on the received signals and instructions stored in memory of the controller. 
       FIG. 2  shows a top view of a detailed illustration of the fuel tank  22 . The fuel tank  22  includes a housing  200  and an outlet  202  in fluidic communication with the fuel injector  28  shown in  FIG. 1 . Continuing with  FIG. 2 , the housing  200  of the fuel tank  22  also includes a first external depression  204 . A mechanical fastener  206  extending through the housing  200  is also shown in  FIG. 2 . The mechanical fastener  206  provides reinforcement to the first external depression  204 , thereby increasing the structural integrity of the fuel tank  22 . The first external depression  204  has a circular geometry with regard to an axis  205  extending through the mechanical fastener  206 . However, other geometries of the first external depression  204  have been contemplated such as oval shapes, square shapes, rectangular shapes, etc. Cutting plane  210  defines the cross-sectional view shown in  FIGS. 3 and 4 . 
     Note that, as discussed with regard to  FIG. 3 , for example, the particular cross section shown has an indented recess (from both the top and bottom in this example, but it may be only from the top, if desired, see  FIG. 6 ). As such in the fuel tank illustrated in  FIG. 6  the housing  200  only includes the first external depression  204 . Additionally, while the figure shows only a single indented recess, multiple recesses may be present. In cross-sections where there is not a recess, both sides of the tank communicate via an open channel between the two sides. For example, as cross-section  290 , as shown in  FIG. 7 , the connecting region is open to each side. 
     Turning now specifically to  FIG. 3 , it shows a cross-sectional view of the fuel tank  22 . The fuel tank outlet  202  is also depicted in  FIG. 3 . As previously discussed, the fuel tank outlet  202  is fluidly coupled to the fuel injector  28  shown in  FIG. 1 . Continuing with  FIG. 3 , the fuel pump  24  is in fluidic communication with the fuel tank outlet  202 . The fuel pump  24  is configured to increase the pressure of fuel and transfer fuel to the fuel tank outlet  202  and other downstream fuel delivery system components. 
     A fuel  300  is shown enclosed in the housing  200  of the fuel tank  22 . The housing  200  has a saddle shape with a first region  302  and a second region  304  joined by connecting region  306 . It will be appreciated that the housing  200  is shaped such that fuel can flow between the first region  302 , the second region  304 , and the connecting region  306 . Although, the housing is shaped with a saddle shape other fuel tank geometries have been contemplated. 
     The housing  200  includes a reinforcement region  308  with a first interior surface  310  and a second interior surface  312  opposing the first in face sharing contact with one another. In one specific example, the first and second interior surfaces  310  and  312  may be welded, glued, etc., to one another. However in other examples, the interior surface may simply be in contact with one another. 
     The mechanical fastener  206  is shown extending through the section of the reinforcement region  308  where the first and second interior surfaces  310  and  312  are in face sharing contact. The mechanical fastener  206  acts to reinforce a selected section of the housing  200  to further strengthen the fuel tank  22  and reduce fatigue on the tank caused by various factors such as high pressures, structural loads from other engine components, etc. 
       FIG. 4  shows a detailed view of the reinforcement region  308  with the mechanical fastener  206  extending therethrough. The first and second interior surfaces  310  and  312  of the reinforcement region  308  are illustrated. Exterior surfaces  400  and  402  included in the reinforcement region  308  are also shown. The profile of the exterior surfaces  400  and  402  form the first external depression  204  and a second external depression  406 . The mechanical fastener  206  includes a first head  408  and a second head  410  coupled to a shaft  412  (e.g., cylindrical shaft). Specifically in one example, the mechanical fastener  206  may be a rivet where the heads  408  and  410  are non-removably attached to the shaft  412 . However, other types of mechanical fasteners have been contemplated such as mechanical fasteners with removable heads. 
     The first head  410  is positioned in the first external depression  204  and the second head  412  is positioned in the second external depression  406 . That is to say that sections of the external surfaces  400  and  402  circumferentially enclose each respective head  408  and  410 . The first and second heads  408  and  410  have a greater diameter than the diameter of the shaft  412 . The aforementioned diameters are measured from the axis  205 . In one example, the axis  205  may be parallel to a vertical axis when the vehicle in which the fuel tank  22  located is on a level surface. Forming the mechanical fastener  206  with the heads  408  and  410  having a greater diameter than the shaft  412  enables movement of the mechanical fastener  206  to be reduced and load dispersion to the housing  200  from the fastener to be increased. Load dispersion may be further increased via washer plates  414  and  416  positioned between respective heads  408  and  410  and exterior surfaces  400  and  402 . The washer plates  414  and  416  may have an annular shape, in one example. Additionally, the washer plates  414  and  416  have a larger diameter than the heads  408  and  410  of the mechanical fastener  206 . Again the diameter of the washer plates  414  and  416  is measured from the axis  205 . In this way, loads transferred from the mechanical fastener  206  to the housing  200  can be distributed over a greater area of the housing, thereby increasing load dispersion. As a result, the likelihood of fuel tank deformation is decreased and fuel tank durability is increased. 
     Additionally, the shaft  412  extends through the first and second interior surfaces  310  and  312  to the exterior surfaces  402  and  404  of the reinforcement region  308 . The mechanical fastener  206  also includes a drain channel  418  extending from a first end  420  of the mechanical fastener  206  to a second end  422  of the mechanical fastener  206 . Although it appears that the drain channel  418  splits the mechanical fastener  206  into two sections this is not the case. Rather, the apparent sections of the mechanical fastener  206  are coupled via a continuous section of the fastener extending therebetween. 
     Specifically in the depicted example, the axis  205  is also the central axis of the drain channel  418 . The axis  205  can be vertically aligned with respect to gravity when the fuel tank  22  is positioned in the wheeled road vehicle  12  positioned on a flat road  15 , shown in  FIG. 1 . Continuing with  FIG. 4 , the drain channel&#39;s central axis is defined from the drain channel&#39;s vertical top most opening (i.e., the first opening  424 ) to its bottom most opening (i.e., the second opening  426 ). Furthermore, the drain channel  418  has no other openings in the depicted example. However, a drain channel having opening other than the openings depicted in  FIG. 4  have been contemplated. It will be appreciated that the drain channel  418  enables water and/or other liquids to drain from vertically above to below through the channel without a pump or other air pressure generating devices but via gravity. However, in other examples a pump, air pressure, etc., may be used to assist in draining the external depression. 
     The drain channel  418  is fluidly separated from the fuel enclosed by the housing  200 . The drain channel  418  includes a first opening  424  at the first end  420  of the fastener and a second opening  426  as the second end  422  of the fastener. It will be appreciated that the openings extend through sections of the first and second heads  408  and  410 , respectively. The first opening  424  opens into the first external depression  204  and the second opening  426  opens into the second external depression  406 . In this way, fluid may be drain from the first external depression  204  through the drain channel  418  and away from the second external depression  406  when the fuel tank is vertically aligned. As a result, fluid accumulated in external recesses in the housing  200  can be reduced (e.g., substantially eliminated). Consequently, the likelihood of corrosion of the housing  200  caused by the accumulated liquid which in some cases can be corrosive is reduced. In other examples, such as an example where the vertical axis extends towards the bottom of the page, fluid may drain in the opposing direction. 
     In one example, the housing  200  is contoured to permit fuel to flow around the reinforcement region  308 . That is to say that the connection between the interior surfaces  310  and  312  does not extend all the way to the sides  212  and  214  of the housing  200 , the sides  212  and  214  being denoted in  FIG. 2 . In this way, the reinforcement region  314  does not divide the fuel tank into different sealed chambers but conversely enables fuel to flow between different interior regions of the fuel tank. 
     Continuing with  FIG. 4 , in one example the mechanical fastener  206  and the housing  200  may be constructed out of different materials. In such an example, the housing  200  may be constructed out of a polymeric material and the mechanical fastener may be constructed out of a metal or vice versa. In other example, the housing  200  and the mechanical fastener  206  may be constructed out of similar materials. 
       FIG. 5  shows another exemplary mechanical fastener  500  extending through the housing  200 . The mechanical fastener  500  share many similarities with the mechanical fastener  206  shown in  FIGS. 2-4 . As such, similar parts are labelled accordingly and redundant description of elements of the fastener is omitted. The mechanical fastener  500  includes a surface  502  extending inward towards the axis  205  (e.g., central axis) of the mechanical fastener  500  at an angle  504  of less than 90 degrees with regard to the axis  205 . The surface  502  enables fluid to flow into the drain channel  418  more easily. 
       FIGS. 1-6  show example configurations with relative positioning and sizing of the various components, although modifications may be made including changing the relative scaling and positioning of the components. If shown directly contacting each other, or directly coupled, then such elements may be referred to as directly contacting or directly coupled, respectively, at least in one example. Similarly, elements shown contiguous or adjacent to one another may be contiguous or adjacent to each other, respectively, at least in one example. As an example, components laying in face-sharing contact with each other may be referred to as in face-sharing contact. As another example, elements positioned apart from each other with only a space there-between and no other components may be referred to as such, in at least one example. As yet another example, elements shown above/below one another, at opposite sides to one another, or to the left/right of one another may be referred to as such, relative to one another. Further, as shown in the figures, a topmost element or point of element may be referred to as a “top” of the component and a bottommost element or point of the element may be referred to as a “bottom” of the component, in at least one example. As used herein, top/bottom, upper/lower, above/below, may be relative to a vertical axis of the figures and used to describe positioning of elements of the figures relative to one another. As such, elements shown above other elements are positioned vertically above the other elements, in one example. As yet another example, shapes of the elements depicted within the figures may be referred to as having those shapes (e.g., such as being circular, straight, planar, curved, rounded, chamfered, angled, or the like). Further, elements shown intersecting one another may be referred to as intersecting elements or intersecting one another, in at least one example. Further still, an element shown within another element or shown outside of another element may be referred as such, in one example, 
     The subject matter of the present disclosure is further described in the following paragraphs. According to one aspect, a reinforced fuel tank is provided. The reinforced fuel tank includes a housing enclosing a fuel, the housing including a reinforcement region having two opposing interior surfaces in face sharing contact with one another and a mechanical fastener extending through the two opposing interior surfaces, the mechanical fastener including a first head positioned within an external depression of the reinforcement region. 
     According to another aspect, a reinforced fuel tank is provided. The reinforced fuel tank includes a housing enclosing a fuel, the housing including a reinforcement region having two opposing interior surfaces in face sharing contact with one another and a rivet extending through the two opposing interior surfaces, the mechanical fastener including a first head contained within an external depression of the reinforcement region. 
     According to another aspect, a reinforced fuel tank is provided. The reinforced fuel tank includes a housing enclosing a fuel, the housing including a reinforcement region where two opposing interior surfaces are in face sharing contact, a rivet extending through the two opposing interior surfaces, the mechanical fastener including a first head contained within an external depression of the reinforcement region, and a washer plate positioned between the first head of the mechanical fastener and an outer surface of the housing. 
     In any of the aspects described herein or combinations of the aspects, the mechanical fastener can include a drain channel extending from a first end of the mechanical fastener to a second end of the mechanical fastener and fluidly separated from the fuel enclosed by the housing. 
     In any of the aspects described herein or combinations of the aspects, the drain channel can include a first opening at the first end of the mechanical fastener and a second opening at the second end of the mechanical fastener. 
     In any of the aspects described herein or combinations of the aspects, the first end of the mechanical fastener can include a surface extending inward toward a central axis of the mechanical fastener at an angle less than 90 degrees with regard to the central axis. 
     In any of the aspects described herein or combinations of the aspects, the mechanical fastener may be a rivet including a second head. 
     In any of the aspects described herein or combinations of the aspects, the mechanical fastener and the housing may be constructed out of different materials. 
     In any of the aspects described herein or combinations of the aspects, the housing may be constructed out of a polymeric material and the mechanical fastener is constructed out of a metal. 
     In any of the aspects described herein or combinations of the aspects, the reinforced fuel tank may further include a washer plate positioned between the first head of the mechanical fastener and an exterior surface of the housing. 
     In any of the aspects described herein or combinations of the aspects, the housing may be contoured to permit fuel to flow circumferentially around the reinforcement region. 
     In any of the aspects described herein or combinations of the aspects, the mechanical fastener may include a drain channel extending from a first end of the mechanical fastener to a second end of the mechanical fastener, the drain channel fluidly separated from the fuel enclosed by the housing. 
     In any of the aspects described herein or combinations of the aspects, the drain channel may include a first opening at the first end of the mechanical fastener and a second opening at the second end of the mechanical fastener and the drain channel may have a central axis therethrough that is vertically aligned with respect to gravity when the fuel tank is positioned in a wheeled road vehicle positioned on a flat road, the central axis defined from the channel&#39;s vertical top most opening to its bottom most opening, the channel having no other openings and enabling water to drain from vertically above to below through the channel without a pump or other air pressure generating devices but via gravity. 
     In any of the aspects described herein or combinations of the aspects, the washer plate may have a larger diameter than the first head of the rivet. 
     In any of the aspects described herein or combinations of the aspects, the rivet may be constructed out of a different material than the housing. 
     In any of the aspects described herein or combinations of the aspects, the mechanical fastener may include a drain channel extending from a first end of the mechanical fastener to a second end of the mechanical fastener, the drain channel fluidly separated from the fuel enclosed by the housing and including a first opening at the first end of the mechanical fastener and a second opening at the second end of the mechanical fastener. 
     Note that the example control routines included herein can be used with various engine and/or vehicle system configurations. The specific routines described herein may represent one or more of any number of processing strategies such as event-driven, interrupt-driven, multi-tasking, multi-threading, and the like. As such, various acts, operations, or functions illustrated may be performed in the sequence illustrated, in parallel, or in some cases omitted. Likewise, the order of processing is not necessarily required to achieve the features and advantages of the example embodiments described herein, but is provided for ease of illustration and description. One or more of the illustrated acts or functions may be repeatedly performed depending on the particular strategy being used. Further, the described acts may graphically represent code to be programmed into the computer readable storage medium in the engine control system. 
     It will be appreciated that the configurations and routines disclosed herein are exemplary in nature, and that these specific embodiments are not to be considered in a limiting sense, because numerous variations are possible. For example, the above technology can be applied to V-6, 1-4, 1-6, V-12, opposed 4, and other engine types. Further, one or more of the various system configurations may be used in combination with one or more of the described diagnostic routines. The subject matter of the present disclosure includes all novel and non-obvious combinations and sub-combinations of the various systems and configurations, and other features, functions, and/or properties disclosed herein.