KR102217701B1 - Fuel tank with improved mechanical resistance - Google Patents

Abstract

A fuel tank having two opposite wall portions, and at least one reinforcing member connecting the two wall portions, wherein the reinforcing member is at least 1.8 between the diameter of the cross-section at the ends and the diameter of the cross-section at at least one intermediate point. It includes a hollow pillar having a ratio of.

Description

Fuel tank with improved mechanical resistance {FUEL TANK WITH IMPROVED MECHANICAL RESISTANCE}

The present invention relates to a fuel tank with improved mechanical resistance.

Plastic fuel tanks constructed for vehicles must meet specifications that specify the maximum allowable amplitudes of warpage in their lower skin. The deflections specified in these specifications should generally be satisfied during aging tests where the tank contains a certain amount of fuel for a given time period (typically several weeks) at a certain temperature (typically 40 °C). The purpose of these features is to ensure that vehicles maintain their lowest ground clearance and to prevent the skin of the tank from contacting the hot spots of the vehicle.

In general, fuel systems in passenger vehicles are configured to maintain a certain amount of liquid fuel at a pressure substantially equal to the ambient pressure. With the introduction of hybrid vehicles and, more specifically, plug-in hybrids configured to run on fuel-free and possibly months, potentially spilling through an activated carbon canister due to diurnal cycles. Maintaining the pressure in the fuel tank to limit the emissions present is a concern of system designers. Also, maintaining the pressure ensures that the composition of the fuel remains the same during storage. However, tanks must be made to withstand this internal pressure. Thus, as described in the patent application WO 2010/122065 in the name of the present applicant, tank reinforcement can be realized by connecting the two opposing tank surfaces to each other using an inner pillar. However, this reinforcement needs to pass three tests that are slightly contradictory:

ㆍ Long-term aging deformation under pressure requiring very strong pillars.

• Handling drop at 1 m and at room temperature without any deterioration in system functionality.

-High speed impact resistance without any damage to the tank skin during impact; It features a 6 m drop test or SLED test at -40 °C.

A straight pillar is the most obvious configuration as it can reduce the stress inside the pillar based on a slightly larger cross-section, but the straight pillar is the most obvious configuration, but the straight pillar is used in high-speed impact tests, e.g. drop or SLED tests (i.e. During the simulated test) could not have good results. In the second step, small notches were added on the inside of the pillar to initiate pillar failure during high-speed impact tests such as drop or SLED tests. However, this did not positively affect the test results.

In the above-mentioned patent application WO 2010/122065, preferably the pillar is a pillar in the sense of the architectural term, i.e. a cylindrical structure with larger cross sections at both ends and a smaller cross section at the center (in other words, the ends thereof A point is specified that is a cross section that decreases from (to its center).

It was surprisingly found that the three requirements (tests) mentioned above can be satisfied by a pillar having a ratio of at least 1.8 and preferably at least 2 between the diameter of the section at the ends and the diameter of the section at the center. Became. Depending on the material from which the pillars are made, this ratio can also be 5 or more.

Accordingly, the present invention relates to a fuel tank having two opposite wall portions, and at least one reinforcing member connecting the two wall portions, wherein the reinforcing member is at least one intermediate point with the diameter of the cross section at the ends. It includes hollow pillars having a ratio of at least 1.8 between the diameters of the cross-sections.

The term “fuel tank” is understood to mean an impermeable tank capable of storing fuel under various and varying environmental and usage conditions. An example of this tank is a tank equipped on vehicles.

The fuel tank according to the invention is preferably made of plastic, in other words, made of a material comprising at least one synthetic resin polymer.

Any type of plastic may be suitable. Plastics belonging to the category of thermoplastics are particularly suitable.

The term “thermoplastic resin” is understood to mean any thermoplastic polymer including thermoplastic elastomers and mixtures thereof. The term “polymer” is understood to mean both homopolymers and copolymers (in particular, binary or ternary copolymers). Examples of such copolymers are random copolymers, linear block copolymers, other block copolymers and graft copolymers.

One polymer that is often used is polyethylene. Excellent results are being obtained using high density polyethylene (HDPE). Preferably, the tank also comprises a layer of fuel impermeable resin, for example EVOH (partially hydrolyzed ethylene/vinyl acetate copolymer). Alternatively, the tank may be surface treated (fluorinated or sulfonated) so that the tank is impermeable to fuel.

A multilayer fuel tank comprising an EVOH layer between two HPDE layers can be used successfully in the frame of the present invention.

The tank according to the invention comprises two opposing wall portions, ie a reinforcing member connecting two portions of the tank wall opposing each other. Preferably, these two are fitted with a lower wall part (a part that is mounted downward to the vehicle and may creep under the weight of the fuel) and an upper wall part (a part that is mounted upward and does not creep little or no during use. Part).

This reinforcing member is rigid by definition, that is, over the life of the tank it does not deform more than a few mm, ideally less than 1 mm. In fact, "deformation" means expansion in the sense that the deformation may separate the two tank wall parts.

According to the invention, this member is a hollow pillar having a cross-section that varies over its length and a wall thickness that represents a negligible percentage (typically 0.2% to 0.5%) of the total volume, i.e. a hollow body of generally cylindrical shape ( It has the shape of a wall) defining an inner volume that is not filled with the constituent material of the wall.

In one embodiment, the “inner volume” above is defined by one outer wall in the shape of a hollow pillar. This embodiment is shown in FIG. 2 to which it is attached. In another embodiment, the “inner volume” may be the volume between several ribs (parallel slices) of the same material, the outer surrounding surface of the ribs having the shape of a hollow pillar. This embodiment is shown in the accompanying FIG. 4.

According to the invention, the pillar has a large cross-section at its ends and a reduced cross-section at at least one intermediate portion. The "diameter" of the cross section means the diameter of the circle in which the cross section is fitted.

Preferably, the portion with the reduced diameter does not extend over the entire length of the pillar. Preferably the portion with the reduced diameter is positioned to cover the maximum stress location in the pillar. In general, the portion with the reduced diameter extends on at most 90% of the length of the pillar, preferably on at most 70% of the length of the pillar, and ideally on at most 50% of the length of the pillar. Preferably, the intermediate point with the reduced diameter is positioned so as not to extend more than 90% of the total length of the pillar and to cover the maximum stress location in the pillar.

In particular if the pillar fulfills other functions, such as, for example, a ventilation function, this position may be limited to a maximum of 20% of the pillar length (to have a maximum inner volume). In addition, in practice this ratio is the length of the pillar (the ratio increases as the length decreases) and also the area (of the smallest diameter cross section) so that the minimum diameter actually meets in only one cross section (or a very limited area of the pillar). It depends on the diameter of the cross section, which can be evolutive. That is, in one embodiment, the diameter of the cross section is not constant in the region of the intermediate point having the minimum diameter cross section.

Further, it is preferable that both ends of the pillar are provided with connecting flanges, that is, portions that are substantially perpendicular to the entire cylindrical surface of the pillar and can be easily attached to the inner surface of the tank. In this embodiment, the diameter of the cross section of the end of the pillar is the outer diameter of the connecting flange. Generally, the flanges are hollow and contain borings/holes having substantially the same dimensions as the lower or upper portion of the pillars just below or above the flanges.

Further, in this embodiment, preferably there are two parts of the pillar length with a transition in the diameter of the pillar, namely a first transition in the flange region and a second transition in the center of the pillar. The first transition is due to the fact that the width of the weld (or other fastening means) is preferably substantially larger than the width of the pillar body, so that the weld is preferably close to the flange. The second transition is preferably substantially intermediate to ensure even performance from both wall portions of the tank (eg upper and lower impacts).

Preferably, the pillar has an axis of rotational symmetry, and the pillar, when viewed in a vertical plane containing the axis, has a diabola-shaped shape (or two opposing parabolas finally connected by an intermediate portion of a constant diameter). Or the shape of two opposing parabolas finally connected by a portion of diameter decreasing toward the center of the middle portion from the parabolic upper sides. More preferably, on each side of the middle portion of the diabolo the parabolic surface extends by means of a cylindrical portion extending up to the above-mentioned flange. In the latter embodiment, the ratio between the diameter of the flange and the diameter of the cylindrical portion is at least 1.25, preferably a ratio of at least 2. Also preferably, the ratio between the diameter of the cylindrical part and the diameter of the middle part is at least 1.5, preferably at least 2.2.

The aforementioned reinforcing pillars are preferably based on a fuel resistant material, preferably plastic, and if the pillars are welded to the tank, the pillars are preferably made of a material compatible with the material of the tank (at least at the surface). Base.

HDPE, POM (poly-oxy-methylene), PEEK (polyether ether ketone), PPA (polyphthalimide), etc. filled with pure HDPE or glass fibers or any other type of filler (natural or polymer fibers) May be suitable. Preferably, these are plastic pillars produced by injection molding. In addition, it is a two-material pillar, i.e., one part of the two-material pillar is made of a material compatible with HDPE and the other part of the two-material pillar is a material (POM, PA, PEEK, PPA, metal, etc.).

Preferably, the pillar is made of two materials (more preferably: HDPE and, reinforced such as POM or polyoxymethylene) and/or for the purpose of resistance (body of the pillar) and the need for attachment (flanges of the pillar). Reinforcing material). In this embodiment, the two parts made of different materials are preferably overmolded. Further, in this embodiment, there are preferably two parts of the pillar length whose cross-section/diameter is reduced/reduced: a first transition part in the overmolding area and a second transition part in the center of the pillar.

According to a preferred embodiment of the present invention, at least a portion of the hollow pillar is an accessory constituent member having an active role (degassing, metering, fuel trap, etc.) within the tank. In general, the accessory discussed comprises at least one active component within the chamber/housing, and in this case, preferably at least a portion of the hollow pillar constitutes at least a portion of the housing. That is, as described in the patent application WO 2010/122065 mentioned above, the wall of the hollow pillar preferably constitutes at least a part of the housing of the accessory, the contents of which are incorporated in this patent application by reference.

According to a first preferred variant of this embodiment of the present invention, the hollow pillar comprises, in its inner volume, at least part of a ventilation system that connects the inside and outside of the tank, generally through a canister or other pollution control device.

In a preferred sub-variation, the hollow pillar is a liquid/vapor separator (i.e. LVS), ie a hollow volume having an inner geometry that allows the hollow pillar to contain vapor droplets present in the fuel vapor.

In another preferred sub-variation, the accessory is a valve of type ROV and/or FLVV, and the active component integrated into the pillar is a float. In this case, at least a portion of the hollow pillar constitutes a chamber in which the float slides.

According to a second preferred variant of this embodiment of the present invention, the hollow pillar acts as a housing for an overcharge prevention device (OPD). In this variant, at least a portion of the hollow pillars constitute a chamber in which the OPD is located. Next, various ROVs may be connected to this OPD device at the inlet.

In one preferred sub-variant, it is possible to combine LVS and OPD functions into pillars.

According to a third preferred variant of this embodiment of the invention, the hollow pillar operates as a fuel trap (i.e., the accessory is a fuel trap), for this purpose, at least one suction for the fuel pump in its inner volume Point, and particularly very preferably, the pump with a filter sucks through it.

According to a fourth preferred variant of this embodiment of the present invention, the hollow pillar comprises a capacity meter and acts as a protective chamber for the meter (ie constitutes a protective housing of the meter, for example). In this case, the functions of the hollow pillar are to filter the influence of the waves (due to the movement of the fuel) and thus reduce the noise of the fuel level measurement; Protecting the measuring element from parasitic capacitance (by choice of material for this purpose); And reducing the influence of the fuel film deposited on the sensing element.

It should be noted that the various variants mentioned above may be combined within one and the same tank, or even within one and the same pillar.

The present invention will be described in more detail with reference to FIGS. 1 to 4.

1 shows an integral pillar according to the invention with a simple shape.
2 shows a three-dimensional version of another embodiment of the present invention.
Figure 3 shows an alternative reinforcement solution that is not within the scope of the present invention.

1 shows an integral pillar according to the invention having a simple shape (with a constant increase in the diameter of the sections); The following reference numerals designate the following components.

1: fuel tank shell

2: Pinch line of fuel tank (i.e. welding line of two pre-moulded parison parts)

3: reinforcing member

The overall diabolo shape of a pillar according to a preferred embodiment is shown in FIG. 2 and can be characterized by an attachment diameter portion AD and a minimum partial diameter portion MSD.

The attachment diameter is chosen very large to hold a slightly larger tank surface, and the deformation is limited to almost zero when there is pressure in the tank. In fact, if it is a small cross section at the tank shell interface, it is necessary to increase the number of pillars as illustrated in FIG. 3. 3 shows a straight pillar configuration with a slightly larger distance between two pillars 1, 1'. This configuration allows a large deformation at the center point of the tank 2 between both pillars, which may require additional pillars between depending on the deformation value and vehicle environment.

On the other hand, the smallest diameter part in the diabolo shape makes it possible to obtain an easy fracture zone in all directions of the impact part.

In particular, high-impact tests are very difficult to simulate, so it was not self-evident to conceive of this configuration. This configuration is the only one that can achieve a reinforced plastic fuel tank that limits tank deformation when the tank is under pressure, combined with an easy fracture zone to protect the tank shell from breakage during high-speed shock tests (drop and/or SLED tests). It seems to be the composition.

The final reinforcing pillar shape has an overall dimensional ratio between the attachment diameter AD and the minimum partial diameter MSD of at least a factor of 1.8, preferably at least a factor 2.

The results obtained using this invention enable the construction of a reinforced plastic based fuel tank, which allows for a significant weight reduction compared to a steel fuel tank and thereby a reduction in emissions.

With other pillar configurations, it is not possible to limit tank deformation at 350 millibars, typically up to 10 mm and pass high impact resistance requirements.

4 shows another embodiment of the present invention. In this embodiment, the structure of the pillar consists of a series of ribs shaped in the same manner as the previous embodiments to control the point of break. An advantage to this embodiment is that the complexity required to form the central portion of the member is reduced. Since the ribs are all in the same line of draw and do not need to have a hollow interior, the slides required to form the member on the end become sufficiently less complex.

Claims (9)

A multi-layer fuel tank comprising an EVOH layer between two HPDE layers,
The fuel tank includes two opposite wall portions, and at least one reinforcing member connecting the two opposite wall portions,
The reinforcing member comprises a hollow pillar, the hollow pillar having a ratio of at least 1.8 between the diameter of the cross section at the ends of the hollow pillar and the diameter of the cross section at at least one intermediate point,
Connection flanges are provided at both ends of the pillar,
The pillar is a plastic pillar manufactured by injection molding, the pillar is made of two materials, and the flange, which is a part of the two-material pillar, is made of a material compatible with HDPE for the necessity of attachment, And the body of the pillar, which is the other part of the two-material pillar, is made of a material having at least one of limited deformation and creep for resistance purposes, and the two parts made of different materials are overmolded. Tank. The method of claim 1,
The intermediate point with a reduced diameter can extend from 50% to 90% of the total length of the pillar and is positioned to cover the maximum stress position of the pillar. The method of claim 1,
The cross-sectional diameter in the region of the intermediate point is not constant, the multi-layer fuel tank. The method of claim 1,
Wherein the pillar comprises two transition portions having a non-uniform diameter in cross section: a first transition portion in a flange region and a second transition portion substantially in the center of the pillar. The method according to any one of claims 1 to 4,
The pillar is a rotational symmetry axis, and a portion having the shape of a diabolo when viewed in a vertical plane including the rotational symmetry axis, or from the intermediate portion or parabolic upper sides of a constant diameter decreases toward the center of the intermediate portion. A multi-layer fuel tank having a cross-section comprising a portion having the shape of two opposing parabolic lines connected by a middle portion of a diameter to. The method of claim 5,
The parabolic surface on each side of the middle portion of the diabolo is extended by a cylindrical portion extending to the connecting flange, and the diameter of the flange is the diameter (A) of the cross section at the ends of the hollow pillar, at least one When the diameter of the cross section at the middle point is B and the diameter of the cylindrical part is C,
A ≥ 1.25 C and
Satisfying C ≥ 1.5 B,
Multi-layer fuel tank. The method of claim 1,
The pillar, wherein the pillar comprises two transition portions having a non-uniform diameter in cross section: a first transition portion in an overmolding area and a second transition portion substantially in the center of the pillar. The method according to any one of claims 1 to 4,
The hollow pillar has an inner volume defined by one outer wall in the shape of a hollow pillar. The method according to any one of claims 1 to 4,
The hollow pillar has an inner volume between several ribs of material, and the outer surrounding surface of the ribs has the shape of a hollow pillar.

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