Mounting structure for flangeless fuel tank

Abstract

An improved mounting structure for a flangeless fuel tank forcibly maintains an air-tightness at joined parts between top and bottom halves of a tank when the fuel tank is welded, thereby reducing the space and weight of the tank. The fuel tank is increased in capacity as much as a space of a flange can be adopted. The mounting structure comprises a top half of a tank protrusively formed at a lower external lateral surface thereof with a plurality of studs, a bottom half of a tank formed with grooves corresponding to the plurality of studs and partially inserted into the lower distal end of the top half of the tank, and fastening members for being fastened to the studs of the top half of the tank so that the top and bottom halves of the tank can be air-tightly welded.

Description

FIELD OF THE INVENTION

The present invention relates to a mounting structure for a flangeless fuel tank and, more particularly, to a mounting structure in which the top half of the tank can be securely and simply assembled with the bottom half of the tank via welding without flanges.

BACKGROUND OF THE INVENTION

In general, vehicles are equipped with metal fuel tanks for storing a certain amount of fuel and continuously supplying fuel to be consumed in engines. A prior art discloses a fuel tank manufactured by joining two halves of a tank along mating circumferential flanges formed in each halves via lap welding.

Another frequently used prior art discloses a fuel tank manufactured by joining top and bottom halves of a tank via seam welding. Generally, a seam welding is a type of electric resistance welding primarily used for seam welding a metal plate, where welding parts of the metal plate overlap and are inserted into a pair of rollers comprising electrodes are inserted, allowing the overlapped welding parts to be welded by rotation of the rollers. The electrode rollers feed the plates and act as seam electrodes at the same time.

The seam welding using a seam welder is usually applied to a seam part to obtain an air-tight sealing such that it is advantageous for the seam welding to be used for welding top and bottom half plates of a tank. However, there is a drawback in that abrasion occurs easily due to friction generated between the seam electrodes and the plates resulting in a frequent change of electrodes, thereby increasing manufacturing costs.

There is another drawback in that the welding quality deteriorates when contact surfaces of the plates are uneven and the welding zone between the electrodes and plates is broad compared to other welding methods, resulting in a greater thermal deformation, which in turn gives rise to cracks in response to fluctuation of fuel or impact.

As a result, many prior arts disclose a fuel tank manufactured by welding a top plate to a bottom plate of a fuel tank via welding methods other than the seam welding method. For example, U.S. Pat. No. 5,626,776 entitled “Flangeless Fuel Tank” has been disclosed. As illustrated in FIGS. 7 and 8, a flangeless fuel tank (10) is comprised of a lower female half (14) and an upper male half (12). Circumferential walls (16, 18) of the female and male halves (12, 14) are interfitted and overlapped areas thereof are welded and integrated. Furthermore, the female and male halves (12, 14) are formed at the overlapped areas thereof with protrusions (20, 22) and a plurality of dimples (30) are formed to fix positions prior to the welding. A laser beam welding apparatus welds the clamped tank halves (12, 14) along the aligned welding lines to create a continuous welding.

However, there is a disadvantage in the flangeless fuel tank welding method thus described according to the prior art in that, although there is an advantage in that the capacity of the tank can be increased as much as the width of the flange and the weight of the tank can be reduced, the protrusions (20, 22) and dimples (30) should be formed at the laser-welding parts of the tank halves (12, 14) in order to improve airtightness and fixing positions during welding.

There is another disadvantage in that it is structurally difficult to have accurate positions and overlapped portions of the welding parts which greatly influence the quality of the welding, and it is difficult to maintain gaps between overlapping portions of the two halves of a tank around their entire circumferential areas at a constant level.

SUMMARY OF THE INVENTION

The present invention is disclosed to solve the aforementioned problems and it is an object of the present invention to provide a mounting structure for a flangeless fuel tank adapted to easily weld top and bottom halves of a tank in a simplified manner and to limit insertion lengths of welding parts.

In accordance with a preferred embodiment of the present invention, there is provided a mounting structure for a flangeless fuel tank in which a lower circumferential end of a top half of a tank is inserted at one part thereof to an inner upper circumferential surface of a bottom half of a tank, and an overlapped portion therebetween is integrally welded, wherein a plurality of studs, each spaced out therebetween, are protrusively formed at an external lower end surface of the top half of the tank. A plurality of grooves are formed at the upper end of the bottom half of the tank to accommodate the plurality of studs, and a plurality of fastening members are used for being fastened to a distal end of each stud and for fastening the joined part between the top and bottom halves of the tank.

In accordance with a second preferred embodiment of the present invention, there is provided a mounting structure for a flangeless fuel tank in which protrusive stoppers are further formed at the inner surface of the bottom half of the tank and each protrusive stopper is distanced from the upper end of the bottom half of the tank.

In accordance with a third preferred embodiment of the present invention, there is provided a mounting structure for a flangeless fuel tank in which the fastening member is formed with a hollow hole formed with female threads corresponding to male threads formed at a circumferential surface of a stud, and an external end of the hollow hole is further formed with a flange for contacting the external surface of the bottom half of the tank.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the nature and objects of the present invention, reference should be made to the following detailed description with the accompanying drawings, in which:

FIG. 1 is a perspective view of a welded structure of an automobile fuel tank according to an embodiment of the present invention;

FIG. 2 is a cross-sectional view taken along line A-A of FIG. 1;

FIG. 3 is a an enlarged cross-sectional view of a welded part according to an embodiment of the present invention;

FIG. 4 is an enlarged and exploded perspective view of principal parts of the present invention;

FIG. 5 is a cross-sectional view of a welded state of FIG. 4;

FIG. 6 is a constitutional view for illustrating a fastening member according to another preferred embodiment of the present invention;

FIG. 7 is an exploded perspective view of an exemplary conventional flangeless fuel tank; and

FIG. 8 is a cross-sectional view of a welded principal part shown in FIG. 7.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The preferred embodiments of the present invention will now be described in detail with reference to the annexed drawings, where the present embodiments are not limiting the scope of the present invention but are given only as an illustrative purpose.

As illustrated in FIGS. 1-5, a mounting structure for a flangeless fuel tank includes a top half of a tank (110) protrusively formed with a plurality of studs (115) at the lower external surface of the top half of the tank, and a bottom half of a tank (120) for being partially inserted into the lower end of the top half of the tank (110). The bottom half of the tank is formed with a plurality of inversely-arched grooves to correspond with the plurality of the studs (115), and a plurality of fastening members (210) are used for being fastened to each stud (115) to couple the top and bottom halves of the tank (110, 120).

Preferably, stoppers (122) are protrusively formed at the inner upper surface of the bottom half of the tank (120) to allow the top half of the tank (110) to be accommodated at a lower end thereof. To be more specific, each stud (115) is shaped of a pin or a bolt and is formed at the external side of the top half of the tank (110). Each stud is formed with male threads. In the first embodiment of the present invention, a nut is exemplified for the fastening member (210) with a hollow hole (212).

Preferably, the hollow hole (212) is formed at an inner circumferential side thereof with female threads for being screwed to the studs (115) and the nut is formed with a flange (215) for contacting the external surface of the bottom half of the tank (120).

Preferably, each stopper (122) protrudes toward the interior of the bottom half of the tank (120), each stopper (122) being arranged oppositely from each other at the inner circumference of the bottom half of the tank (120). Preferably, the stopper (122) can partially be formed in a ring-shape at the inner circumference of the bottom half of the tank (120).

The operation of the present invention will now be described in detail with the accompanying drawings.

First, the assembly process will be explained. When a lower distal end of the top half of the tank (110) is partially inserted into the interior of the bottom half of the tank (120), the lower distal end of the top half of the tank (110) is accommodated by the interference of the stopper (122) of the bottom half of the tank (120) and the stud (115) of the top half of the tank (110) is fitted into the groove (125) of the bottom half of the tank (120).

Successively, when the distal end of the externally-protruded stud (115) is assembled with the fastening member (210) and rotated, threads formed at the hollow hole (212) of the fastening member (210) and threads formed at the external circumference of the stud (115) are mutually assembled, and the flange (215) of the fastening member (210) contacts the external side of the bottom half of the tank (120).

The joined parts between the bottom half of the tank (120) and the top half of the tank (110) are mutually and tightly abutted by a screwing force from the fastening member (210) and the stud (115). At this time, the screwing force from the fastening member (210) is transmitted to the stud (115) while the flange (215) of the fastening member (210) is supported onto the external side of the bottom half of the tank (120), thereby creating a force of pulling the top half of the tank (110) outward. In other words, a gap at the joined parts between the bottom half of the tank (120) and the top half of the tank (110) can be adjusted by the fastening force between the stud (115) and the fastening member (210), and the gap can be appropriately maintained for welding of the joined parts.

Successively, the joined parts between the top and bottom halves of the tank (110, 120) are integrally assembled via welding in which an air-tight and water-tight fuel tank without a flange can be manufactured.

For reference, the joined part between the top and bottom halves of the tank (110, 120) is approximately within 0.2 mm in case of laser welding, plasma welding and soft brazing, and in case of carbon dioxide welding, the gap within approximately 0.5 mm must be maintained.

Meanwhile, FIG. 6 shows a second embodiment of the present invention in which a nut runner (300) is adopted instead of a nut as a fastening member of the first embodiment. A mounting structure for a flangeless fuel tank according to the second embodiment of the present invention includes a runner body (310) horizontally operable on a vertically movable jig (400) to allow accommodation with the top half of the tank (110) and a bottom half of the tank (120), a fastening member (320) rotatably mounted on the upper side of the runner body (310) for fastening a stud (115), and a support (330) mounted at a position close to the fastening member (320) for supporting one side of the bottom half of the tank (120).

In the structure equipped with nut runner thus described, the top and bottom halves of the tank (110, 120) provisionally assembled with the jig (400) are lifted to rotate the fastening member (320) and to be fastened to the stud (115), and the support (330) abuts on one lateral surface of the bottom half of the tank (120). Successively, the jig (400) is retracted to pull the top half of the tank (110) to allow maintaining an air-tightness with the bottom half of the tank (120). The circumference at the joined parts is assembled via welding while the air-tightness is maintained between the top and bottom halves of the tank (110, 120).

Successively, when the welding is finished, the jig (400) is detached to complete the airtight fuel tank.

Although the present embodiment has described an air-tight structure where the top and bottom halves of a tank (110, 120) are fastened by studs (115), it is not intended to limit the invention to the precise form disclosed, and modifications and variations are possible in light of the above teachings or may be acquired from practice of the invention. It is intended that the scope of the invention be defined by the claims appended hereto, and their equivalents.

As apparent from the foregoing, the present invention is an improvement of a mounting structure for a flangeless fuel tank by forcibly maintaining an air-tightness at joined parts between top and bottom halves of a tank when the flangeless fuel tank is welded. There is an advantage in the mounting structure for a flangeless fuel tank thus described according to the embodiments of the present invention in that space and weight can be reduced, and a fuel tank increased in capacity as much as a space of a flange can be adopted.

Claims

1. A mounting structure for a flangeless fuel tank in which a lower circumferential end of a top half of a tank (110) is partially inserted to an inner upper circumferential surface of a bottom half of a tank (120) and an overlapped portion therebetween is integrally welded, wherein a plurality of studs (115), each spaced out therebetween, are protrusively formed at the external lower end surface of said top half of the tank (110), and a plurality of grooves (125) are formed at the upper end of said bottom half of the tank (120) to accommodate the plurality of said studs (115), and a plurality of fastening members (210) are used for being fastened to a distal end of each said stud (115) and for fastening a joined part between said top half of the tank and said bottom half of the tank (110, 120).

2. The mounting structure according to claim 1, further comprising protrusive stoppers (122) formed at the inner surface of said bottom half of the tank (120), each said protrusive stopper distanced from the upper end of said bottom half of the tank (110).

3. The mounting structure according to claim 1, wherein each said fastening member (210) is formed with a hollow hole (212) formed with female threads corresponding to male threads formed at a circumferential surface of said stud (115), and the external end of said hollow hole (212) is further formed with a flange (215) for contacting the external surface of said bottom half of the tank (120).