US-12623531-B2 - Internal reinforcement element for a tank made of plastic for a motor vehicle

US12623531B2US 12623531 B2US12623531 B2US 12623531B2US-12623531-B2

Abstract

An internal reinforcing element for a plastic tank for a motor vehicle is made as a single piece and includes: a central portion which in cross section is in the shape of an annulus sector, defining a main axis of the reinforcing element and having a first surface area, the central portion including a network of ribs extending radially in relation to the main axis, referred to as network of radial ribs; and two axial end portions which are situated one on each side of the central portion when considering the main axis, each of the axial end portions having an end surface of curved and oblong shape inscribed inside the cross section of the central portion and having a second surface area smaller than the first surface area.

Inventors

Pierre OSZWALD
Thomas PERET
Dominique Madoux

Assignees

PLASTIC OMNIUM ADVANCED INNOVATION AND RESEARCH

Dates

Publication Date: 20260512
Application Date: 20230531
Priority Date: 20220601

Claims (10)

1 . An internal reinforcing element for a plastic tank for a motor vehicle, made from a single piece and comprising: a central portion which in cross-section has the shape of an annulus sector, defining a main axis of the reinforcing element and having a first surface area, the main axis passing through the center of rotation of the annulus sector perpendicular to the annulus sector, the central portion comprising a network of ribs extending radially in relation to the main axis, referred to as a network of radial ribs, and two axial end portions which are situated one on each side of the central portion when considering the main axis, each of the axial end portions having an end surface of curved and oblong shape inscribed inside the cross section of the central portion and having a second surface area smaller than the first surface area, wherein a cross-section of the internal reinforcing element along a plane parallel to the main axis of the radial rib tapers from the central portion to the axial end portions.
2 . The reinforcing element according to claim 1 , made entirely of high-density polyethylene (HDPE).
3 . The reinforcing element according to claim 1 , wherein the end surfaces each comprise a network of axial protuberances.
4 . The reinforcing element according to claim 3 , wherein the end surfaces each comprise an openwork assembly of axial ribs surrounding the network of axial protuberances.
5 . The reinforcing element according to claim 1 , wherein the network of radial ribs comprises straight ribs extending perpendicularly or parallel to the main axis, defining therebetween recesses of generally rectangular parallelepiped shape, and cylindrical ribs, defining therebetween recesses of generally cylindrical shape.
6 . The reinforcing element according to claim 1 , wherein the radial ribs form an asymmetrical network.
7 . The reinforcing element according to claim 1 , comprising gripping means located on a side wall of the central portion.
8 . The reinforcing element according to claim 1 , wherein the end surfaces have a shape corresponding to a homothety of the annulus sector with a ratio k less than or equal to 1, in which shape each of its four corners is replaced by a rounded edge.
9 . A plastic tank for a motor vehicle comprising an internal reinforcing element according to claim 1 .
10 . A method for manufacturing a plastic tank for a motor vehicle, wherein an internal reinforcing element according to claim 1 is welded to two opposing internal walls of the tank.

Description

BACKGROUND OF THE INVENTION Field of the Invention The invention relates to an internal reinforcement element for a tank made of plastic for a motor vehicle. It also relates to a plastic tank for a motor vehicle comprising an internal reinforcing element and a method of manufacturing a plastic tank for a motor vehicle. Description of the Related Art Traditionally, motor vehicle fuel tanks are designed to hold a quantity of fuel at a pressure almost identical to atmospheric pressure. With the advent of hybrid vehicles, also known as HEV (Hybrid Electric Vehicle), MHEV (Mild-Hybrid Electric Vehicle) or PHEV (Plug-in Hybrid Electric Vehicle), in other words motor vehicles comprising an internal combustion engine and one or more electric motors, which can potentially run for several months without using the internal combustion engine, it is preferable to maintain pressure in the fuel tank to reduce the passage of fuel vapors through an activated carbon filter, also known as a canister. This is achieved by isolating the canister from the tank using a valve such as a Fuel Tank Isolation Valve (FTIV). Plastic fuel tanks of this type are therefore subject to dimensional variations over their lifetime. This occurs initially as soon as they exit the mold as a result of cooling thereof which is accompanied by shrinkage of the material, said plastic tanks being obtained by extrusion blow-molding a parison, or during use thereof as a result in particular of positive or negative pressure of their contents, or as a result of thermal expansion thereof over their life, or due to the temperature variation caused by the day/night cycle, or as a result of aging. Typically, plastic fuel tanks for motor vehicles, more particularly plastic fuel tanks for hybrid motor vehicles, comprise an internal reinforcing element in the form of a pillar joining two opposing internal surfaces of the tank. Such a pillar must withstand various tests, such as long-term aging or a handling drop from a height of 1 meter, without degrading the properties of the fuel tank. For example, document WO2012/139962 A1 discloses an hourglass-shaped circular pillar that is highly resistant to axial stresses due to tension/compression phenomena, as well as to aging and strength tests. However, such a pillar is relatively sensitive to stresses caused by bending and/or torsion. BRIEF SUMMARY OF THE INVENTION The invention aims in particular to overcome these disadvantages of the prior art. More precisely, one of the objectives of the invention is to provide a reinforcing element for a plastic tank for a motor vehicle that can withstand not only axial stresses due to tension/compression phenomena, but also bending and torsion phenomena, said internal reinforcing element being easily obtained by injection molding. To this end, the invention has as its object an internal reinforcing element for a plastic tank for a motor vehicle, made as a single piece and comprising: a central portion which in cross-section has the shape of an annulus sector, defining a main axis of the reinforcing element and having a first surface area, the main axis passing through the center of rotation of the annulus sector perpendicular to the annulus sector, the central portion comprising a network of ribs extending radially in relation to the main axis, referred to as a network of radial ribs, andtwo axial end portions which are situated one on each side of the central portion when considering the main axis, each of the axial end portions having an end surface of curved and oblong shape inscribed inside the cross section of the central portion and having a second surface area smaller than the first surface area. The curved shape of the central portion and its ribbed structure make it possible to better distribute the stresses transmitted to the internal reinforcing element in different directions, as demonstrated by finite element analyses carried out by the inventors. It is understood that such an internal reinforcing element resists bending and torsion phenomena better than the prior art pillar characterized by its structure that can be described as unidirectional. What's more, the curved shape of the internal reinforcing element allows it to better overcome the constraints associated with its positioning in the tank. For example, the concave part of the internal reinforcing element can be used to surround an accessory provided in the tank, so that the volume of this concave part is not entirely lost. This type of arrangement is not possible with the prior art pillar. Simulation tests have also shown that if the end surfaces are not oblong, i.e. if they have protruding corners, then stress is concentrated at these corners, forming a zone of brittleness in the internal reinforcing element. The inventors have found that replacing these protruding corners with rounded edges, thus forming the oblong shape, results in a better distribution of stresses over the entire internal reinforcing elem