Vehicle fuel tank

The inside wall of a fuel tank, and a sub-component are provided with locking means in the form of complementary formations that allow the sub-component to be coupled to the inside surface of the fuel tank wall. Interlocking of the complementary formations is achieved by moving the sub-component towards the wall providing angular movement to the sub-component relative to the fuel tank.

FIELD

This invention relates generally to fuel tanks for vehicles.

INTRODUCTION

Vehicle fuel systems must be leak tight under all conditions, and must ensure that the fuel received is moved safely through the fuel filler pipe to the fuel tank, and that the vapour generated during the filling process is moved to an appropriate onboard vapour storage container. Typically, fuel tanks will have various parts attached to the fuel tank shell in order to satisfy these requirements.

Fuel tanks are primarily made from either metal or plastic. The wall of a plastic fuel tank may comprise one or multiple layers, which may be designed with barrier properties to enhance the plastic fuel tank's ability to keep volatile organic compounds inside the tank.

An example of a part commonly attached to plastic vehicle fuel tanks is a gas vent valve, typically used to permit air to flow into the fuel tank as fuel is consumed from (and exits) the tank, and to further permit fuel vapour to flow from the fuel tank as fuel is loaded therein, during normal operation of the vehicle. In order to prevent fuel spillage when a vehicle is tipped or rolled, gas vent valves can be configured to close in response to a change in the orientation of the fuel tank.

A part is most commonly attached to a fuel tank shell by either welding, or mechanically attaching the part to the fuel tank. Example attachment methodologies advanced to date include those described in U.S. Pat. Nos. 5,083,583; 6,058,963; 6,584,996; 7,059,305; 7,228,847; 7,290,675; and, 7,455,190; and in U.S. Publication Nos. 2002/0020705 and 2006/0260129.

Conventionally, attaching a part to a fuel tank requires that a hole be cut into the tank body where the part is to be attached, which can significantly diminish the fuel tank barrier properties. An object of the present invention is to provide a means for attaching a part to the inside of a fuel tank without compromising the integrity of the tank wall.

SUMMARY

In one broad aspect, there is provided a fuel tank having a wall with an inside surface defining the interior of the tank, and locking means coupling a fuel tank sub-component to said inside surface of the wall without compromising the integrity of the wall, said locking means comprising complimentary male and female formations on said sub-component and said inside surface respectively, said formations being shaped to permit engagement of the formation on the sub-component with the formation on the wall by movement of the sub-component towards the wall and subsequent interlocking of said formations by angular movement of the sub-component with respect to the wall in a first direction.

The sub-component may be a valve or other part having a housing provided with locking formation(s), or the formation(s) may be on a separate housing that receives the part.

The part for mounting in the interior of the fuel tank may be, for example, a gas vent valve, a control valve, a fuel limit vent valve, baffles, a line retaining clip, or an internal retention clip. The housing of/for the part may have a vapour exit port and may be injection molded from a resilient material. In one embodiment, the material may be a plastic material selected from the group of: polyoxymethylene and polyphthalamide.

In one embodiment, the male formation is on the sub-component and may comprise a plurality of locking elements and a plurality of retention wings. Further, the female formation is on the inside surface of the fuel tank and may comprise a plurality of angled ramps for sliding engagement with the plurality of locking elements, a plurality of locking recesses for accepting the plurality of locking elements when the sub-component is coupled to the inside surface of the wall, and a plurality of undercut portions for engagement with the plurality of retention wings when the sub-component is coupled to the inside surface of the wall. More specifically, the plurality of angled ramps may comprise two diametrically opposed angled ramps.

In another embodiment, the fuel tank may further comprise alignment means aligning the sub-component within the fuel tank, said alignment means comprising a second set of complimentary male and female formations on the sub-component and the inside surface respectively, said second formations being shaped to permit alignment of the sub-component within the fuel tank prior to coupling.

The fuel tank may be manufactured by a method selected from the group of: stamping, hydro forming, blow molding, injection molding, and twin sheet vacuum forming.

In another broad aspect, there is provided a sub-component for coupling to an inside surface of a wall of a fuel tank without compromising the integrity of the wall, said sub-component comprising a formation shaped to engage with a complementary formation on the wall of the fuel tank by movement of the sub-component towards the wall and subsequent interlocking of said formations by angular movement of the sub-component with respect to the wall, said formations comprising male and female formations, respectively.

The sub-component may be a valve or other part having a housing provided with locking formation(s), or the formation(s) may be on a separate housing that receives the part.

The housing may be injection molded. In one embodiment, the housing may be a plastic material selected from the group of: polyoxymethylene and polyphthalamide. Further, the plastic material must be resistant to fuel.

The part for mounting in the interior of the fuel tank may be a gas vent valve, a control valve, a fuel limit vent valve, baffles, a line retaining clip, or an internal retention clip. The housing may have a vapour exit port and may be injection molded from a resilient material. In one embodiment, the material may be a plastic material selected from the group of: polyoxymethylene and polyphthalamide.

In one embodiment, the male formation is on the sub-component and may comprise a plurality of locking elements and a plurality of retention wings.

DESCRIPTION OF VARIOUS EMBODIMENTS

Referring first toFIG. 1, a fuel tank designed for securing a fuel tank sub-component therein without compromising the integrity of the fuel tank wall is shown by way of example and is generally designated by reference numeral100. Part of the fuel tank100has been cut away in order to show the interior thereof. A sub-component secured within the fuel tank100is shown inFIG. 1by way of example and is generally designated by reference numeral200. The sub-component200is attached to the inside wall104of the fuel tank100manually or using an automated process whereby an extended robot arm enters the fuel tank100through an opening to perform the attachment.

The fuel tank100is made of plastic, as is the sub-component200, and the sub-component200is configured to house a valve (not shown). The sub-component200is coupled to the fuel tank100without compromising the surrounding inside surface125of the fuel tank100by providing a female formation on the inside surface125of the fuel tank100designed to engage with a complementary male formation provided on the sub-component200. Throughout the description, reference may be made to complementary formations (or complementary design features) “on the fuel tank”, or “provided on the fuel tank”. Such references shall be understood to mean “on the inside surface of the fuel tank”, or “provided on the inside surface of the fuel tank”, respectively.

Referring now toFIG. 2, the sub-component200ofFIG. 1is shown in perspective view, in the absence of the fuel tank100. As mentioned above, a male formation is provided to the sub-component200for engagement with a complementary female formation provided on the inside surface125of the fuel tank100(FIG. 1). The male formation comprises locking elements210and retention wings220. The illustrated embodiment comprises two locking elements210and two retention wings220and functions similarly to a bayonet-style fitting (employing a twist to lock technique to secure the sub-component to the interior of the fuel tank). A person of ordinary skill in the art will appreciate that the sub-component200may be designed with a different number of locking elements210and retention wings220.

Each locking element210is designed for engagement with a complementary recess (or pocket) of the inside wall104of the fuel tank100(FIG. 1). In the illustrated embodiment, the locking elements210are substantially cylindrical in shape and have a rounded contact portion215(i.e. a substantially hemispherical end portion). The contact portion215of the locking element210is the portion thereof (typically the end portion) configured for engagement with the complementary recess (or pocket) of the fuel tank100when coupling the sub-component200to the fuel tank100(FIG. 1). Those ordinarily skilled in the art will appreciate that the shape of the locking elements210may vary provided that the contact portions215are designed complementary to locking recesses formed in the fuel tank100, which will be described further below. As will also be discussed further below, when the sub-component200is coupled to the inside wall104of the fuel tank100, the contact portions215of the locking elements210engage with locking recesses on the fuel tank100(FIG. 1) to prevent rotation of the sub-component200about a central axis230thereof, and to restrict the sub-component's200mobility in the upward direction (indicated by the arrow labeled U).

The male formation provided to the sub-component200also comprises retention wings220. In the illustrated embodiment, the sub-component200has two retention wings220substantially diametrically opposed. As mentioned above, the number of retention wings220provided to the sub-component200may be more or less than two. Further, it will be appreciated that where two retention wings220are used, they need not be substantially diametrically opposed. As will be discussed further below, when the sub-component200is coupled to the fuel tank100(FIG. 1), the retention wings220frictionally engage with complementary undercuts provided in the fuel tank100to restrict the sub-component's200mobility in the downward direction (indicated by the arrow labeled D).

The male formation provided to the sub-component200includes optional assembly fingers255in association with the retention wings220. Each wing normally (but not necessarily) will be provided with an assembly finger. As discussed further below when the sub-component200is coupled to the fuel tank100(FIG. 1), the assembly fingers255are the first to engage the complementary undercuts provided in the fuel tank100and in effect guide the retention wings200to frictionally engage the complimentary undercut provided by the fuel tank100.

Additionally, the sub-component200comprises an additional (or second) male formation shaped to permit alignment of the sub-component200within the fuel tank100when engaged with an additional (or second) female formation provided in the fuel tank100(FIG. 1). In the illustrated embodiment, the additional male formation of the sub-component200comprises the male locating element240protruding from the centre of the sub-component200. The male locating element240is provided with a pivot surface245, which when pressed against a complementary female formation in the fuel tank100, indicates the proper positioning of the sub-component200for subsequent coupling to the fuel tank100(FIG. 1).

As seen inFIG. 3, the pivot surface245is planar and protrudes higher than the rest of the male locating element240. Accordingly, the pivot surface245may provide the first point (or surface) of contact between the sub-component200and the fuel tank100when the latter is offered to the former for coupling. Further, the top surface of the male locating element240is beveled from the outer periphery of the pivot surface245to the outer periphery of the male locating element240. As will be discussed further below, a complementary bevel is provided around a central locating surface of the fuel tank100(FIG. 1) to facilitate proper alignment of the sub-component200within the fuel tank100prior to, and during coupling.

With returning reference toFIG. 1, the sub-component200illustrated has an opening250for receiving a valve or other part (not shown) that is required to be attached inside a fuel tank100. Examples of parts that may be required to be attached inside a fuel tank100include, but are not limited to, valves (e.g. gas vent valves, control valves, and fuel limit vent valves), baffles, line retaining clips, and internal retention clips. The sub-component200illustrated is exemplary only. It is designed for use with a separate gas vent valve (not shown) and has a vapour exit port252to allow fuel vapour to flow from the valve (not shown) to a desired location, e.g. an onboard vapour storage container (not shown), through a hollow vapour flow tube254of the sub-component200. The area around opening250may be provided with a range of fastening means, such as mechanical, welds, adhesive, press-fit, rivets or screws. Within the opening may be threads, such as for holding a fuel system component in place. Seals may be provided, particularly where one of the alternate non-threaded fastening means are used.

Referring toFIG. 2, the sub-component200illustrated has two metal disks256installed one on the top of each of the diametrically opposed locking elements210and inside the rounded contact portion215. A third metal disk is inserted into the pivot surface245on the male locating element240. These disks allow for subsequent confirmation that the sub-component200is in the correct and final locked position during the assembly process.

Exemplary technologies for confirming correct location include metal detection, x-ray, and industrial imaging technology. In general, the technology used to locate the metal disks would verify proper location having regard to visual features (registration points) on the exterior surface of the tank, which may be either purposely placed registration points, or visual features that are already part of the tank itself.

As noted previously, instead of being a multiple-piece assembly (as in the illustrated embodiment), the sub-component200may be unitary wherein the locking formation(s) are integrally formed on the valve or other part itself. For example, the male formations of the sub-component200, as described above, may be integrally formed on a housing of the valve.

As will be discussed in further detail below, an appropriate amount of resiliency is required of the sub-component200. This resiliency may be achieved by injection-molding the sub-component200from certain plastic materials. The sub-component200must also be fuel resistant. In a preferred embodiment, the sub-component200may comprise either polyoxymethylene or polyphthalamide plastic with fuel-resistant properties.

Reference is now made toFIG. 4, in which a female formation of the inside wall104of the fuel tank100is illustrated by means of a bottom view of the cut away fuel tank100ofFIG. 1, in the absence of sub-component200. The female formation of the fuel tank100is complementary to the male formation of the sub-component200as described above, and may comprise angled ramps110, locking recesses112, and undercut portions120.

In the embodiment illustrated, two locking recesses112are formed in the inside wall104of the fuel tank100, as are the angled ramps110for sliding engagement with the locking elements210of the sub-component200(FIG. 2). The ramps110slope inward (i.e. towards the interior of the fuel tank100) in the direction of the arrows, i.e. from a distal end114of the ramp110(furthest from the corresponding locking recess112) towards the proximal end116of the ramp110(adjacent to the corresponding locking recess112). In a preferred embodiment, the profile of each angled ramp110largely conforms to the profile of the contact portion215of the complementary locking element210of the sub-component200, thereby facilitating sliding of the locking elements210along the angled ramps110in the direction of the arrows inFIG. 4. It will be appreciated that a different number of angled ramps110may be formed in the fuel tank100should a sub-component200with a different number of locking elements210be provided.

A locking recess112is formed in the inside wall104of the fuel tank100adjacent the proximal end116of each angled ramp110. The locking recesses112are essentially hemispherical seats for receiving the locking elements210of the sub-component200. The orientation of the locking recesses112relative to each other corresponds to the orientation of the locking elements210of the sub-component200relative to each other. For example, where the locking elements210of the sub-component200are diametrically opposed, the complementary locking recesses112in the fuel tank100will also be diametrically opposed. It will be appreciated that, as was the case with the number of angled ramps110, more or less than two locking recesses112may be formed in the fuel tank100depending on the number of locking elements210provided on the sub-component200. It will also be appreciated that the locking recesses112need not be hemispherical in shape; rather, they need only complement the shape of the locking elements210of the sub-component200.

In the illustrated embodiment, the formation on the inside wall104of the fuel tank100further comprises undercut portions120. As shown inFIG. 1, the undercut portions120may be formed by appropriately shaping the wall104of the fuel tank100. The undercuts are appropriately oriented and spaced from the other components of the formation on the fuel tank100so as to be frictionally engaged first by the assembly fingers255and then the retention wings220of the sub-component200when the sub-component is coupled to the fuel tank100. As apparent fromFIG. 1, when the sub-component200is coupled to the fuel tank100, the undercuts restrict the sub-component's200mobility by restricting its movement towards the center of the fuel tank100.

With continuing reference toFIG. 4, an optional second female formation on the inside wall104of the fuel tank100is described. The second female formation provides alignment means for the sub-component200within the fuel tank100and comprises a central locating surface145for engagement with the complementary pivot surface of the sub-component200when the sub-component200is offered to the inside wall104of the fuel tank100prior to coupling. In a preferred embodiment, the central locating surface145of the fuel tank100conforms largely with the pivot surface245of the sub-component200. For example, where the pivot surface245is planar (as in the embodiment ofFIG. 3), the central locating surface of the fuel tank100is also planar. It will be appreciated by those skilled in the art that the central locating surface145and the pivot surface245are not required to be planar. For example, in some embodiments, the central locating surface and pivot surface may be conical in configuration. In the illustrated embodiment, the second female formation in the fuel tank100also comprises a beveled surface148, largely conforming to the beveled top surface of the male locating element240between the periphery of the pivot surface245and the periphery of the top surface of the male locating element240.

The female formations described above in connection with the inside surface wall104of the fuel tank100may be provided by blow molding the fuel tank100using an appropriately configured mold. Alternatively, the fuel tank100can be manufactured with the appropriate formations through stamping and hydro forming processes (for metal fuel tanks), and injection molding and twin sheet vacuum forming processes (for plastic fuel tanks).

Installation of the sub-component200within the fuel tank100is now described with reference toFIGS. 1, 2, and 4 to 7. The sub-component200is offered to the inside the wall104of the fuel tank100proximate the female formations provided therein (i.e. the sub-component200is moved towards the wall104). Proper alignment of the sub-component200within the fuel tank100is achieved by pressing the pivot surface245of the sub-component200against the central locating surface145on the fuel tank100. In the embodiment illustrated, the locking elements210are aligned with the distal ends114of the angled ramps110such that the retention wings220do not interfere with the undercuts120. Pressure towards the wall104is applied to a portion of the sub-component200(typically a central portion), and the sub-component200is rotated (i.e. provided an angular movement) with respect to the first wall104to interlock the formation on the sub-component200with the formation on the fuel tank100.

The sub-component200is turned in the direction indicated by the arrows inFIG. 4such that the locking elements210slide up the angled ramps110. By maintaining the applied pressure throughout the rotation of the sub-component200, the angled ramps110increasingly displace the locking elements210, causing the sub-component200to flex at the attachment regions260(FIG. 1) of the locking elements210. Once the sub-component200is rotated such that the locking elements210reach the locking recesses112, energy stored in the resilient material of the sub-component200causes the attachment members260to return to their natural (un-flexed) position and the locking elements210to snap into the locked position within the locking recesses112. Once the sub-component200has reached this position, the retention wings220are engaged with the undercuts120and the sub-component200is effectively coupled to the wall104of the fuel tank100, thereby immobilizing the sub-component200within the fuel tank100without compromising the integrity of the wall104.

FIGS. 5, 6 and 7are diagrammatic illustrations showing the sequence of movement of one of the locking element210into the corresponding locking recess112. InFIG. 5, the retention wings220are shown prior to entering the corresponding undercuts120formed in the tank. InFIG. 6, the retention wings are within the respective undercuts and fully flexed at the attachment regions260. InFIG. 7, the locking element210is seated within the associated recess112and the attachment regions260of the retention wings have partially relaxed.

It will of course be appreciated that the preceding description relates to a particular preferred embodiment of the invention and that many modifications are possible, some of which have been indicated above, and others of which will be apparent to a person skilled in the art. For example, the male and female formations of the fuel tank and sub-component may be interchanged (i.e. a male formation may be provided to the fuel tank and a complementary female formation may be provided to the sub-component).

Male locating element240may be a separately-formed piece that assembles on the main body portion comprising the retaining wings. For example, the male locating element240may be positioned in an opening of the main body portion, and is locked into place when the assembly is fitted to the corresponding female formations on the tank. While the sub-component is generally regarded as being a plastic component, other materials may be used including magnesium alloys (thixomolding), other metals such as aluminum using a die cast forming process and thermosetting materials.

Finally, it is to be noted that a plurality of sub-components may be used to attach a single part to a tank—for example, baffles may require multiple contact points within a tank.