Abstract:
A method and apparatus for preventing vehicle instability from sloshing fuel and aiding in the structural strength of a vehicle fuel tank by using a vee-shaped baffle that is inserted into the warm fuel tank a predetermined distance and plastic welded inside the plastic fuel tank.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an article and a method to provide improved fuel tank components in a motor-vehicle, and in particular, a welded baffle component to be used in motor vehicle fuel tanks. 
     2. Description of the Prior Art 
     Baffles have been used for many years in fuel tanks to reduce the effect of the fuel sloshing when the vehicle is in motion. When a vehicle is moving, fuel can flow rapidly from one side of the tank to the other. In a fuel tank without a baffle, the fuel sloshing within a tank can cause instability in the vehicle and reduce control and potentially cause it to swerve or tip over. Additionally, the sloshing of a large amount of fuel against the walls of the tank can cause severe structural strains on the tank walls. A correctly placed baffle interrupts the sloshing fuel and slows the fuel wave so the effect of the fuel movement is less, thereby increasing the stability of the vehicle and reducing the strain on the walls of the tank. 
     Baffles in fuel tanks are becoming more important as larger automobiles are being produced by the automakers. Large-sized sports utility vehicles are now common on the road. Automakers have many even larger sports-utility vehicles planned for release in the next few years. These large vehicles have poor fuel efficiency compared to smaller vehicles and require larger fuel tanks. They also have a higher center of gravity than typical passenger vehicles, which makes them inherently less stable than passenger vehicles. With large volumes of fuel slosh, vehicle stability and control can become an issue. Using effective baffles in these vehicles reduces concerns. 
     There are two critical aspects of baffle design: the attachment method of the baffle to the fuel tank and the shape of the baffle. Baffle design must also be balanced with weight, cost and ease of manufacture considerations. Because of the weight issue, the majority of fuel tanks used on passenger vehicles are plastic, so the attachment method must be consistent with plastics manufacturing. Plastic fuel tanks are, however, not as strong as metal and require the baffle to also act as a support mechanism for the tank. 
     According to NASA studies for rocket fuel tanks, the ideal baffle design is made up of rigid annular rings. These rings, however, add a significant amount of weight to a vehicle and make the tank unduly heavy. This is not acceptable in automobile design where weight is such a significant factor. 
     U.S. Pat. No. 6,220,287 B1 issued to Wolf uses a plurality of semi-round baffles in different locations extending from the inner side walls of the tank towards the center. While lighter than the annular ring design, the manufacturing of a tank containing these baffles would encompass multiple process steps to attach the many baffles and would be cost-prohibitive in the auto industry. 
     In U.S. Pat. No. 5,850,933 issued to Pazik, a plastic molded fuel tank is described which contains a traverse baffle that is molded into the tank. While the manufacturing is simplified in this design, the baffle design is non-ideal because the baffle only supports the plastic tank in one direction. 
     In U.S. Pat. No. 4,526,286 issued to Jung et al., a thermoplastic fuel tank is also described where the baffles are molded into the tank. The baffles are protrusions from the tank walls with openings in the baffles. This is a better baffle design for dampening and strength because of the openings and two-direction strengthening. However, the baffle protrusions and openings in the baffles make for a very complicated molding tool with many slides and steps. The cycle time in the tool is thus increased, making it less feasible for the high volume automotive industry. 
     Many of the above concerns are dealt with in U.S. Pat. No. 4,350,258 issued to Rogers. The fuel tank baffle is mounted in an interlocking arrangement to the fuel tank. In this patent, a simple baffle is added to the fuel tank without complicating the manufacturing, but the added component creates a rattle risk. An interlocking arrangement can loosen over time and cause the noise that a vehicle driver or passenger may complain about. 
     Welding of the baffle to the fuel tank was described in U.S. Pat. No. 1,562,074 issued to Baum. The weld could not be made inside the metal tank. The baffle protruded through the tank and was welded from the outside. This method of welding from the outside created a weak point at the joint, which is undesirable. 
     From the above it is seen that there remains a need for a system and method of manufacturing a baffle inside a vehicle fuel tank that is cost effective for mass production, prevents sloshing fuel from causing vehicle instability, minimizes weak points, aids in the structural integrity of the fuel tank and fits securely to prevent noise. 
     SUMMARY OF THE INVENTION 
     In accordance with the present invention, a fuel tank baffle is provided where a vee-shaped baffle is plastic welded to the interior of the plastic fuel tank. The baffle is welded to the fuel tank while the fuel tank is still hot from thermoforming. 
     A fuel tank, made up of a thermoplastic material, is generally manufactured using a thermoforming process. When the tank is cooled enough to retain its shape, but still hot from the thermoforming process, the plastic baffle is placed inside the warm fuel tank. The baffle is then plastic welded to the fuel tank at the top of the baffle. 
     The baffle is a vee with a rounded vertex at its bottom, the bottom portion hereinafter referred to as the vertex. The vee-shape allows the baffle to support the fuel tank while the fuel tank cools and gives the fuel tank added structural support when in use in a vehicle. 
     In the preferred embodiment of the invention, a series of holes perforate the baffle to keep the fuel flowing from the front of the vehicle to the back of the vehicle or back to front or side to side at a minimum velocity. Braces are added to the sides of the baffle to increase the rigidity of the baffle. The top of the vee have two sets of stepped “feet” sticking outward therefrom. The ends of the feet serve two purposes. One set of feet sink into the warm fuel tank to gain better retention of the baffle by the fuel tank. The second set of feet creates a positive stop point for the insertion of the baffle to the fuel tank to aid the assembly. 
     Advantages of the present invention include the manufacturing of the baffle apart from the manufacture of the fuel tank. The shape of the baffle is not limited by the shape of the fuel tank, as in previous designs, since it is manufactured separately. The unrestricted unique shape of the baffle also reduces the noise of the fuel sloshing back and forth in the tank. The fuel tank can be produced cheaply and efficiently by not having to consider the geometry of the baffle in the tool design. The baffle can be molded separately, allowing for an ideal shape for a fuel tank baffle, without complicated molding. The finished product is lightweight and has high structural integrity for a plastic component. 
     Additional benefits and advantages of the present invention will become apparent to those skilled in the art to which the present invention relates from the subsequent description of the preferred embodiments and the appended claims, taken in conjunction with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of an embodiment of the fuel tank baffle of the present invention; 
     FIG. 2 is a side view of the fuel tank baffle; 
     FIG. 3 is a perspective view of the baffle as it is assembled to the fuel tank; and 
     FIG. 4 is a side view of a close-up of the attachment of the baffle to the fuel tank. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to the drawings, as seen in FIG. 1, a fuel tank baffle  10  according to the principles of the present invention is perspectively shown. The baffle  10  is generally of a vee-shape and has an open end  13  and a closed end  15  and has two sides,  12  and  14 . The sides  12  and  14  are differing heights to conform to the fuel tank  50  (shown in FIG. 3) and are herein referred to as short side  14  and tall side  12 . While the sides  12  and  14  differ in height in this embodiment, they may alternatively be of the same height. The short side  14  and tall side  12  converge to the closed end  15  at the bottom of the baffle  10  in a vertex  16 . 
     At the top of each side  12  and  14  are stepped feet for attaching the baffle  10  to the fuel tank  50 . The stepped feet consist of axial feet  22  and  24  and lateral feet  18  and  20 . A series of axial feet  24  are arranged in an alternating fashion between a series of lateral feet  20  atop the open end of the short side  14 . A series of the axial feet  22  are also arranged in an alternating fashion between the series of lateral feet  18  atop the open end of the tall side  12 . The axial feet  24  and  22  are generally aligned with the sides  14  and  12 , respectively. The lateral feet  20  and  28  are generally projecting outward from the sides  14  and  12 , respectively. 
     The sides  12  and  14  are structurally supported by braces  26  and  28 . The braces  26  and  28  serve to prevent deformation of the baffle  10  when in use in a vehicle. Brace  26  extends laterally from side  12  to side  14  on edge  32 . Brace  28  is on the side of the baffle  10  opposing brace  26  and extends from side  12  to side  14  on edge  34 . 
     As readily seen in FIG. 1, perforations  36  are distributed throughout side walls  12  and  14 . The perforations  36  serve to direct flow and slow fuel sloshing in the fuel tank  50  when the vehicle is in operation. The perforations  36  are preferably of a generally round or oval shape, but other shapes are also possible. The perforations  36  may be of uniform size or varying size, and are set in an optimized shape and size pattern for controlling and slowing the fuel flow for different size and design fuel tank applications, as determined by engineering evaluation for each application. 
     Referring now to FIG. 2, a side view of the baffle  10  is shown facing edge  34 . The general vee-shape of the baffle  10  is clearly viewed in FIG. 2 as tall side  12  and short side  14 , and rise from the vertex  16  at the bottom of the baffle  10 . Axial feet  22 ,  24  are shown generally extending in the planes of sides  12  and  14 , while lateral feet  18 ,  20  extend outwards therefrom. Braces  26  and  28 , extending between the sides  12  and  14 , are staggered in their distance from vertex  16  to add strength and reduce flexing of the baffle  10  during vehicle operation. 
     Referring now to FIG. 3, the baffle  10  is shown in a similar side view as in FIG. 2, however, in FIG. 3, the fuel tank  50  is now assembled about the baffle  10 . 
     The fuel tank  50  consists of top half  52  and bottom half  54 . Top half  52  is made up of a top wall  64  and side walls  66  and  68 . The side walls  66  and  68  terminate in perimeter flanges  56  and  58 , respectively. Bottom half  54  consists of bottom wall  70  and side walls  72  and  74 . The side walls  72  and  74  terminate in perimeter flanges  60  and  62 , respectively, which correspond with the flanges  56 ,  58  of the top half  52 . The top half  52  and bottom half  54  cooperate to define an internal chamber  53  of the fuel tank  50  to contain fuel and baffle  10 . 
     The top half  52  and bottom half  54  are generally manufactured using thermoforming. While the top half  52  is still warm from processing, the baffle  10  is assembled to the top half  52 . The axial feet  22  on tall side  12  partially melt into the top perimeter flange  56  during assembly. The axial feet  24  on short side  14  partially melt into the perimeter flange  58  during assembly. The warm bottom half  54  is then assembled to the top half  52  capturing the baffle  10  between the perimeter flanges  56 ,  58  of top half  52  and perimeter flanges  60 ,  62  of bottom half  54 , respectively. The perimeter flanges  56 ,  58 ,  60  and  62  may then be further secured together by conventional mechanical means. 
     Referring now to FIG. 4, a close-up view of the attachment between the baffle  10  and the fuel tank  50  is shown at the top of tall side  12 . The axial feet  22  extend into and are partially melted into the top half  52  at top perimeter flange  56  upon assembly. Positive feedback is felt as the operator assembles the baffle  10  to the top half  52  when the top of the lateral feet  18  contact the flange  56 , stopping the operator from further pushing the baffle  10  into the fuel tank  50 . The bottom half  54  is then assembled to the top half  52  and baffle  10  assembly to capture the baffle  10  between the top half  52  and bottom half  54  at perimeter flange  56  and perimeter flange  60 . The perimeter flanges  56 ,  58 ,  60  and  62  may then be further secured together by conventional mechanical means. 
     While the above description constitutes the preferred embodiments of the present invention, it will be appreciated that the invention is susceptible to modification, variation and change without departing from the proper scope and fair meaning of the accompanying claims.