Plastic fuel tank with support element

Abstract

The invention relates to a plastic fuel tank (10) for a vehicle, comprising: a bottom (14) and a top (12); at least one side wall (16) extending between the bottom (14) and the top (12); at least one support element (18), where the at least one support element (18) has an elongate shape and comprises a longitudinal axis, a first end side and a second end side comprising at its axial ends, a flange (24) comprising at the first end side or at the second end side, and is arranged between the bottom (14) and the top (12), where the flange (24) comprises a flange width; wherein the top (12) or the bottom (14) comprises an integrated receiving structure for receiving the flange (24) of the support element (18), and wherein the receiving structure is formed by the top (12) or the bottom (14) and forms a stepped cavity comprising a first cavity (28) and a second cavity.

Description

Technical Field

[0001] The present invention relates to a plastic fuel tank for a vehicle, a motor vehicle including said fuel tank, and a method for manufacturing said fuel tank. Background Art

[0002] Various types of fuel tanks are generally known from the prior art. Generally, fuel tanks are made of plastic materials or metals. In particular, when the fuel tank is made of plastic materials, due to the material properties and the relatively small thickness of the tank body, the mechanical stiffness of the tank may be rather low. To provide a higher stiffness of the plastic fuel tank, support elements (also referred to as stiffening elements or strengthening elements) that allow absorption of mechanical forces applied to the fuel tank may be provided. These support elements may have a longitudinal shape and may be made of plastic materials.

[0003] According to common plastic fuel tanks, the support elements are generally made of thermoplastic materials, where the support elements are welded to the bottom and the top of the fuel tank. Generally, the support elements are made of the same material as the fuel tank, thus providing the same melting temperature, thereby simplifying the welding process.

[0004] Although the fuel tanks mentioned, which include support elements connected to the fuel tank body via welding joints, include several benefits, such types of fuel tanks are also associated with some drawbacks. For example, the manufacturing process is generally challenging and time-consuming because the connection of the support elements to the tank body during the welding process is sensitive to any movement of the support elements. Summary of the Invention

[0005] In view of the above, an object of the present invention is to provide a plastic fuel tank that allows for easy and efficient manufacturing. Another object of the present invention is to provide a plastic fuel tank that can be produced at a low manufacturing cost. Yet another object of the present invention is to provide a plastic fuel tank with improved mechanical stiffness.

[0006] To solve the above objects, the present invention provides a plastic fuel tank for a vehicle, wherein the plastic fuel tank includes the following parts:

[0007] A bottom and a top;

[0008] At least one side wall extending between the bottom and the top, wherein the bottom, the top, and the at least one side wall define an internal space of the plastic fuel tank, and the internal space is configured to receive fuel;

[0009] At least one support element, wherein the at least one support element has an elongated shape and includes a longitudinal axis, includes a first end side and a second end side at its axial ends, includes a flange at the first end side or the second end side and is arranged between the bottom and the top, wherein the flange includes a flange width;

[0010] Wherein the top or the bottom includes an integrated receiving structure for receiving the flange of the support element, wherein the receiving structure is formed by the top or the bottom and forms a stepped cavity including a first cavity and a second cavity, wherein:

[0011] The first cavity is defined by an outer part of the top or the bottom forming a first cavity outer wall and at least one first cavity side wall extending from the first cavity outer wall, wherein the first cavity is arranged adjacent to the second cavity;

[0012] The second cavity is at least defined by a second cavity side wall, and the second cavity is arranged between the first cavity and the internal space of the plastic fuel tank;

[0013] The first cavity includes a first cavity width, the second cavity includes a second cavity width, wherein the first cavity width is greater than the second cavity width; and

[0014] Wherein the flange width is greater than the second cavity width and less than or equal to the first cavity width.

[0015] The plastic fuel tank according to the invention allows for a stable attachment of the support element to the plastic fuel tank. In addition, according to the invention, it is not necessary to weld the outer surface of the support element to the top and bottom of the fuel tank, which simplifies the manufacturing process. Thus, the manufacturing cost is reduced and the manufacturing speed is increased.

[0016] The at least one side wall described above can be designed as an annular wall surrounding the internal space of the fuel tank. According to some embodiments, the fuel tank may further include a plurality of side walls, such as four side walls arranged in a rectangular manner with respect to each other to form the internal space of the fuel tank. The fuel tank may also include more than four side walls adjacent to each other and forming the internal space of the fuel tank. The present invention can be implemented regardless of the number of side walls.

[0017] The support element is configured to support the fuel tank in case of overpressure and / or underpressure, thereby preventing or at least reducing the possibility of damage or rupture of the fuel tank. The support element further reduces the possibility of possible cracks in the top and bottom of the fuel tank. Thus, the support element helps to increase the stiffness and thus helps to increase the lifespan of the fuel tank. According to the invention, depending on the size and specific design of the fuel tank, a plurality of support elements can be provided, wherein the present invention can be implemented regardless of the specific number of support elements.

[0018] The flange of the support element can be designed as an integral part of the support element or, alternatively, as a separate part connected to the body of the support element. In the latter case, the flange can be welded or mechanically connected to the body of the support element. According to the invention, the flange is provided at the first end side and / or the second end side of the support element and has a greater width compared to the adjacent parts of the support element. According to some embodiments, a single flange can be provided, which is received in a receiving structure at the top or bottom. In a preferred embodiment of the invention, the support element includes a flange at each of its end sides, with one flange being received in a first receiving structure formed in the top and one flange being received in a second receiving structure in the bottom of the fuel tank.

[0019] According to some embodiments of the invention, the support element and the flange can have a rotationally symmetric shape, wherein the flange can preferably include a disc shape. In the latter case, the first cavity and the second cavity can have a cylindrical shape, wherein the diameter of the first cavity is larger than the diameter of the second cavity. According to some embodiments, the stepped cavity can include a second cavity having a uniformly decreasing width compared to the first cavity. For example, the first cavity and the second cavity can each include a cylindrical shape, wherein the diameter of the second cavity is reduced by 10%, 20%, 30% or 50% compared to the first cavity. According to some embodiments, the second cavity can not include a rotationally cylindrical shape, wherein the width of the second cavity is reduced at least along one cross-section of the stepped cavity compared to the first cavity. By providing a receiving structure including a stepped cavity having a first cavity and a second cavity (with a smaller width compared to the first cavity), the flange can be locked within the receiving structure and fixed therein in a mechanically stable manner.

[0020] The exterior of the top or bottom refers to the part of the top or bottom that is at a greater distance from the interior space of the tank compared to the side walls of the first cavity and the second cavity. In particular, the exterior can refer to the part of the top or bottom that includes the portion with the greatest distance to the interior space of the fuel tank.

[0021] Preferably, the side walls, the bottom and the top are integrally designed. In addition, the side walls of the first cavity, the side walls of the second cavity and the exterior of the bottom or top can be integrally designed. Thus, the design of the fuel tank can be simplified and, as a result, the manufacturing cost can be further reduced.

[0022] According to a preferred embodiment of the present invention, the flange includes an outer surface pointing away from the axial center of the support element, wherein this outer surface of the flange is welded to the outside of the top or bottom. Thus, a more stable fixation of the support element within the receiving structure can be provided. Additionally, according to this embodiment, the receiving structure can significantly assist the welding process by positioning the flange into the desired position and by holding the flange in the desired position during the welding process. Thus, the alignment of the support element during the welding process is significantly improved.

[0023] According to some embodiments of the present invention, the height of the first cavity is less than or equal to the height of the flange. Thus, the flange is axially clamped within the first cavity, thereby significantly enhancing the mechanical stability of the fixation. According to some embodiments, the height of the first cavity is equal to the height of the flange. However, the height of the first cavity can also be chosen to be slightly less than the height of the flange. In the latter case, the clamping force exerted by the receiving structure increases. Note that the top is typically formed of a rather thin plastic structure. Thus, the receiving structure generally includes some flexibility such that if the height of the flange is slightly greater than the height of the first cavity, the flange can also be received within the first cavity. Additionally, when the flange is further welded to the top or bottom of the fuel tank, providing a first cavity with a height slightly less than the height of the flange, the resulting clamping force leads to an improved welding process because the axial clamping force is exerted by the receiving structure on the flange, pressing the flange and the bottom or top of the fuel tank together during the welding process. This results in an improved welding process and a more stable attachment between the support element and the top and / or bottom of the fuel tank.

[0024] According to some embodiments of the present invention, the width of the first cavity can be greater than the width of the flange. According to some preferred embodiments of the present invention, the width of the first cavity can be equal to the width of the flange. Since the width of the first cavity is equal to the width of the flange, the flange is radially clamped within the first cavity of the receiving structure. This enables the flange to be stably fixed in the radial direction within the first cavity of the receiving structure. Additionally, if the outer surface of the flange is welded to the outside of the top or bottom, the fixation of the support element in the radial direction simplifies the welding process because the flange of the support element remains in a radially stable position during the welding process.

[0025] According to some further preferred embodiments of the present invention, the first cavity includes a tapered shape, wherein the width of the first cavity decreases in the direction from the outer wall of the first cavity to the second cavity. Thus, when received within the first cavity, the flange is centered in the first cavity in the radial direction.

[0026] In addition, the flange may also include a conical shape, where the width of the flange decreases in the direction from its outer surface to the axial center of the support element. The conical angle can be selected according to the conical angle of the first cavity. In other words, the conical angle can be selected identically or at least similarly. Therefore, the radial centering of the flange within the first cavity can be improved.

[0027] According to some preferred embodiments of the present invention, the support element includes a rotationally symmetric shape. In addition, the first cavity, the second cavity, and the flange may include a rotationally symmetric shape.

[0028] Preferably, the support element includes a conical shape, where the width of the support element decreases from its axial end to its axial center. Thus, in the case where an increased force acts on the fuel tank, for example during an accident, the support element can be intentionally broken at a predetermined point.

[0029] According to some preferred embodiments of the present invention, the support element includes at least one breaking point, which is configured to break when an axial force exceeding a predetermined force threshold is applied to the support element. The breaking point can be ensured by providing a notch at a specific position of the support element. The depth of the notch can be adjusted according to the selected force threshold.

[0030] According to further preferred embodiments of the present invention, the side wall, bottom, and top of the fuel tank are integrally formed. Thus, the structure of the fuel tank is simplified and the manufacturing cost can be reduced.

[0031] According to a further embodiment of the present invention, the side wall, bottom, and top are at least partially made of a thermoplastic material. In addition, the support element and the receiving structure can be made of a thermoplastic material.

[0032] According to some preferred embodiments of the present invention, the side wall, bottom, and top are at least partially made of one of the following materials: polyethylene (PE), high-density polyethylene (HDPE), polypropylene (PP), polyethylene terephthalate (PET), polystyrene (PS), polymethyl methacrylate (PMMA), polyoxymethylene (POM), polyphenylene sulfide (PPS), polyphthalamide (PPA), polyether ether ketone (PEEK), polyamide-imide (PAI), or polyaryletherketone (PAEK). According to a further embodiment of the present invention, the support element and / or the receiving structure can be at least partially made of one of the said materials.

[0033] According to some embodiments of the present invention, the fuel tank is designed as a single tank or a saddle tank.

[0034] According to the present invention, a motor vehicle is proposed, where the motor vehicle includes a fuel tank according to one of the above embodiments.

[0035] According to the present invention, a method for manufacturing a fuel tank according to one of the above-described embodiments is provided, wherein the method employs a blow molding process, and the method comprises the following steps:

[0036] Providing a preform made of a plastic material within the inner cavity of a mold, wherein the preform defines the inner cavity, and wherein the mold comprises two halves and is designed to form the desired shape of the fuel tank, and wherein the mold comprises a first opening and a second opening, the first opening being arranged at a first side of the mold and the second opening being arranged at a second side of the mold, the second side being opposite to the first side, the first opening being configured to insert the preform into the mold, and the second opening being configured to insert a support element into the inner space of the preform;

[0037] Inserting a support element into the inner cavity of the preform;

[0038] Blowing compressed air into the preform so as to expand the preform;

[0039] Bringing the two halves of the mold closer to each other so as to form the expanded preform according to the shape of the mold;

[0040] Cooling the inner cavity of the mold so as to solidify the formed fuel tank.

[0041] The method according to the present invention renders the process for manufacturing a plastic fuel tank effective and cost-reducing. According to the method proposed by the present invention, it is not necessary to force-weld the outer surface of the support element to the components of the fuel tank. However, according to some embodiments of the present method, the outer surface of the flange may be welded to the top or bottom of the fuel tank in order to increase the attachment strength between the support element and the top / bottom of the fuel tank. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Hereinafter, the present invention will be further described in the context of the drawings, wherein the drawings show the following:

[0043] Figure 1 is a fuel tank according to the prior art,

[0044] Figure 2 is an embodiment of a fuel tank according to the present invention,

[0045] Figure 3 is Figure 2 an enlarged view of the embodiment of the present invention shown in

[0046] Figure 4 and is an enlarged view of another embodiment of the present invention.

[0047] In Figure 1In [the figure], a common fuel tank 10 known from the prior art is schematically shown. The fuel tank 10 includes a top 12, a bottom 14, and side walls 16. The side walls 16 can be designed as an annular wall surrounding the inner space 22 of the fuel tank 10. A support element 18 is provided within the inner space 22. The support element 18 is arranged between the top 12 and the bottom 14 of the fuel tank 10. The support element 18 includes an outer surface 20, which is generally welded to the top 12 and the bottom 14 during the manufacturing process of the fuel tank 10.

[0048] In Figure 2 [the figure], an embodiment of the fuel tank 10 according to the present invention is schematically shown. Similar to Figure 1 the fuel tank shown, Figure 2 the fuel tank 10 also includes a top 12, a bottom 14, and side walls 16 that define the inner space 22 of the fuel tank 10. The fuel tank 10 further includes a support element 18, which includes a flange 24 at its outer end. In addition, the fuel tank 10 includes an integrated receiving structure within the top 12 and the bottom 14. Each receiving structure includes a first cavity 28 and a second cavity 30, where the width of the first cavity 28 is greater than the width of the second cavity 30, and where the width of the flange 24 is greater than the width of the second cavity 30 and less than the width of the first cavity 28. Thus, the receiving structure is configured to receive the flange 24 within the first cavity 28. Therefore, the support element 18 can be stably attached to the fuel tank 10 in a simplified and effective manner.

[0049] In Figure 3 [the figure], an enlarged view of the embodiment shown in Figure 2 is shown. As can be seen from Figure 3 , the receiving structure includes a first cavity 28 and a second cavity 30, where the width of the second cavity 30 is less than the width of the first cavity 28. Thus, the receiving structure formed within the top 12 of the fuel tank 10 is configured to receive the flange 24 of the support element 18. As further shown in Figure 3 , the first cavity 28 is formed by an outer portion 26 of the top 12 that forms the outer wall of the first cavity and a first cavity side wall 32. The first cavity side wall 32 extends from the outer portion 26 and defines the height of the first cavity 28. The second cavity 30 is defined by a second cavity side wall 34, which defines the height and width of the second cavity 30. As can be further seen in Figure 3 , the width of the flange 24 is greater than the width of the second cavity 30 and slightly less than the width of the first cavity 28. Thus, the flange 24 of the support element 18 is stably fixed within the receiving structure.

[0050] In Figure 4 [the figure], an enlarged view of another embodiment of the present invention is shown. In Figure 4As can be seen, the first cavity includes a conical structure, where the diameter of the cavity decreases in the direction from the outside 26 of the top 12 of the fuel tank 10 to the second cavity 30. At the same time, the flange 24 includes a conical structure, where the diameter of the flange decreases from the outer surface of the flange 24 facing the outside 26 to the axial center of the support element 18. As Figure 4 Further shown in, the conical angle of the first cavity 28 and the conical angle of the flange 24 are selected to be the same. Therefore, the flange 24 is radially centered within the first cavity 28.

[0051] Reference numerals

[0052] 10 Fuel tank

[0053] 12 Top

[0054] 14 Bottom

[0055] 16 Side wall

[0056] 18 Support element

[0057] 20 Outer surface of the support element

[0058] 22 Internal space

[0059] 24 Flange

[0060] 26 Outside of the top / bottom

[0061] 28 First cavity

[0062] 30 Second cavity

[0063] 32 Side wall of the first cavity

[0064] 34 Side wall of the second cavity

Claims

1. A plastic fuel tank (10) for a vehicle, the plastic fuel tank (10) comprising: bottom (14) and top (12); at least one side wall (16) extending between the bottom (14) and the top (12), wherein the bottom (14), the top (12) and the at least one side wall (16) define an interior space (22) of the plastic fuel tank (10), the interior space (22) being configured to receive fuel; at least one support element (18), wherein the at least one support element (18) has an elongated shape and comprises a longitudinal axis, comprises a first end side and a second end side at its axial ends, comprises a flange (24) at the first end side or the second end side and is arranged between the top portion (12) and the bottom portion (14), wherein the flange (24) comprises a flange width; wherein the top portion (12) or the bottom portion (14) comprises an integrated receiving structure for receiving the flange (24) of the support element (18), wherein the receiving structure is constituted by the top portion (12) or the bottom portion (14) and forms a stepped cavity comprising a first cavity (28) and a second cavity (30), wherein: The first cavity (28) is defined by an outer portion (26) of the top or the bottom forming a first cavity outer wall and at least one first cavity side wall (32) extending from the first cavity outer wall, wherein the first cavity (28) is arranged adjacent to the second cavity (30); The second cavity (30) is defined by at least a second cavity sidewall (34), and the second cavity (30) is disposed between the first cavity (28) and the interior space (22) of the plastic fuel tank; and The first cavity (28) comprises a first cavity width, and the second cavity (30) comprises a second cavity width, wherein the first cavity width is greater than the second cavity width; and The flange width is greater than the second cavity width and less than or equal to the first cavity width.

2. The fuel tank (10) according to claim 1, characterized in that The flange (24) comprises an outer surface directed away from an axial center of the support element (18), wherein the outer surface of the flange (24) is welded to the outer portion (26) of the top portion or the bottom portion.

3. The fuel tank (10) according to claim 1 or 2, characterized in that: The height of the first cavity (28) is less than or equal to the height of the flange (24).

4. The fuel tank (10) according to any one of claims 1 to 3, characterized in that The width of the first cavity (28) is equal to the width of the flange (24).

5. The fuel tank (10) according to any one of claims 1 to 4, characterized in that The first cavity (28) comprises a tapered shape, and a width of the first cavity (28) decreases in a direction from an outer wall of the first cavity to the second cavity (30).

6. The fuel tank (10) according to any one of claims 1 to 5, characterized in that The support element (18) comprises a rotationally symmetrical shape.

7. The fuel tank (10) according to any one of claims 1 to 6, characterized in that The support element (18) comprises a tapered shape, wherein the width of the support element (18) decreases from its axial ends to its axial center.

8. The fuel tank (10) according to any one of claims 1 to 7, characterized in that The support element (18) comprises at least one breaking point, the at least one breaking point being configured to break when an axial force exceeding a predetermined force threshold is applied to the support element (18).

9. The fuel tank (10) according to any one of claims 1 to 8, characterized in that The side wall (16), the bottom (14) and the top (12) of the fuel tank are integrally formed.

10. The fuel tank (10) according to any one of claims 1 to 9, characterized in that The sidewall (16), the bottom (14) and the top (12) are at least partially made of thermoplastic material.

11. The fuel tank (10) according to any one of claims 1 to 10, characterized in that The side wall (16), the bottom (14) and the top (12) are at least partially made of any one of the following materials: polyethylene (PE), high-density polyethylene (HDPE), polypropylene (PP), polyethylene terephthalate (PET), polystyrene (PS), polymethyl methacrylate (PMMA), polyoxymethylene (POM), polyphenylene sulfide (PPS), polyphthalamide (PPA), polyetheretherketone (PEEK), polyamide-imide (PAI) or polyaryletherketone (PAEK).

12. The fuel tank (10) according to any one of claims 1 to 11, characterized in that The fuel tank (10) is designed as a single tank or a saddle tank.

13. A motor vehicle comprising a fuel tank (10) according to any one of claims 1 to 12.

14. A method for manufacturing a fuel tank (10) according to any one of claims 1 to 12 by using a blow molding process, wherein the method comprises the following steps: providing a parison made of a plastic material in an inner cavity of a mold, wherein the parison defines an inner cavity, the mold comprising two halves and being designed to form a desired shape of the fuel tank, the mold comprising a first opening and a second opening, the first opening being arranged at a first side of the mold and the second opening being arranged at a second side of the mold, the second side being opposite to the first side, the first opening being arranged for inserting the parison into the mold, and the second opening being arranged for inserting the support element into an inner space of the parison; Disposing a support element in the inner cavity of the parison; blowing compressed air into the parison to expand the parison; bringing the two halves of the mold closer to each other to form an expanded parison according to the shape of the mold; The inner cavity of the mold is cooled, thereby solidifying the formed fuel tank.

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