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EP-4739524-A1 - BLADDER FOR A FUEL TANK

EP4739524A1EP 4739524 A1EP4739524 A1EP 4739524A1EP-4739524-A1

Abstract

The invention relates to a bladder (1) defining a variable-volume sealed enclosure for a fuel tank, wherein the sealed enclosure comprises a bellows (2) that is compressible in a Z-axis direction, the bellows (2) comprises a set E1 of folds (3), the folds of the set E1 of folds (3) not all being identical to one another, characterised in that each fold (3 1 ; 3 2 , ..., 3 1 (3 1 - 1 ,..., 3 n ) of a subset E2 of folds of the set E1 of folds (3) is in the shape of an elongate, flat, closed ring A when it is projected orthogonally onto a plane XY perpendicular to the Z-axis, the ring A having an outer length Lext and an inner length Lint in a longitudinal direction of axis X in the plane XY, the ring A also having an outer width l ext and an inner width lint in a transverse Y-axis direction in the plane XY, the Y-axis being perpendicular to the X-axis, such that the ratio (L ext - L int ) / (l ext - l int ), referred to as ratio R, is strictly greater than 1.

Inventors

  • OSZWALD, Pierre
  • MADOUX, DOMINIQUE
  • COING, Jean-François
  • JEANNEL, Hugo
  • SHIN, Changwook

Assignees

  • OPmobility C-Power Belgium Research

Dates

Publication Date
20260513
Application Date
20240705

Claims (15)

  1. Bladder (1) defining a variable-volume sealed enclosure for a fuel tank, in which the sealed enclosure comprises a bellows (2) compressible in a Z-axis direction, said bellows (2) comprises a set E1 of folds (3), the folds of said set E1 of folds (3) not all being identical to each other, characterized in that each fold (3 1 , 3 2 ,…, 3 i , 3 i+1 ,…, 3 n ) of a subset E2 of folds of the set E1 of folds (3) has the shape of an elongated, flat and closed ring A when projected orthogonally onto an XY plane perpendicular to the Z axis, said ring A having an external length L ext . and an internal length L int . in a longitudinal direction of axis X in the XY plane, said ring A also having an external width l ext . and an internal width l int . along a transverse direction of axis Y in the XY plane, the axis Y being perpendicular to the axis X, such that the ratio (L ext . L int . ) / (l ext . l int . ), called ratio R, is strictly greater than 1.
  2. Bladder (1) according to the preceding claim, characterized in that the ratio R is between 1.1 and 2.0, preferably, the ratio R is chosen to be substantially equal to 1.5.
  3. Bladder (1) according to any one of the preceding claims, characterized in that the set E1 of folds (3) contains an odd number of folds.
  4. Bladder (1) according to any one of the preceding claims, characterized in that the subset E2 of folds contains the same number of folds as the set E1 of folds (3).
  5. Bladder (1) according to any one of the preceding claims, characterized in that the area S i of a ring A i of a first ply (3 i ) of the subset E2 of plies is strictly greater than the area S i +1 of a ring A i +1 of a second ply (3 i+1 ) adjacent to the first ply (3 i ) of the subset E2 of plies and includes the latter in the XY plane.
  6. Bladder (1) according to the preceding claim, characterized in that the first fold (3 i ), respectively the second fold (3 i + 1 ), of the subset E2 of folds has a first height h i , respectively a second height h i + 1 , in the direction of the Z axis, and the bellows (2) is configured to have: a first configuration, called the working configuration, in which the bellows (2) is compressed in the direction of the Z axis, and a second configuration, called the rest configuration, in which the bellows (2) is not compressed in the direction of the Z axis and in which the first height h i of the first fold (3 i ) is strictly greater than the second height h i +1 of the second fold (3 i+1 ).
  7. Bladder (1) according to any one of the preceding claims, characterized in that the bellows (2) is made up of two opposite half-bellows (2a, 2b), mutually symmetrical with respect to a median plane P parallel to the XY plane, each half-bellows (2a, 2b) having a general external shape substantially inscribed in a fictitious pyramid with a rectangular base, said rectangular base being included in the median plane P.
  8. Bladder (1) according to any one of the preceding claims, characterized in that the ring A has an internal radius r i nt . and an external radius r ext . in the XY plane, such that the ratio r ext . / r int . is strictly greater than 1.
  9. Assembly comprising a bladder (1) according to any one of claims 1 to 8, characterized in that it further comprises a protective casing (6) for the bladder (1).
  10. Fuel tank (10) for a motor vehicle comprising at least one bladder (1) according to any one of claims 1 to 8 extending inside the fuel tank (10).
  11. Use of at least one bladder (1) according to any one of claims 1 to 8 in a fuel tank (10) for a motor vehicle, the at least one bladder (1) being intended to limit the increase in pressure inside the fuel tank (10).
  12. Motor vehicle (20), in particular a hybrid vehicle, comprising a fuel tank (10) according to claim 10.
  13. Method of manufacturing a fuel tank (10) for a motor vehicle according to claim 10, comprising the following steps: (a) have a fuel tank (10), b) having at least one bladder (1) according to any one of claims 1 to 8, c) compress the bellows (2) in the Z-axis direction, d) introducing the at least one bladder (1) inside the fuel tank (10) through an opening provided in a wall of the fuel tank (10), e) securing the at least one bladder (1) inside the fuel tank (10) such that the at least one bladder (1) extends inside the fuel tank (10).
  14. Method for manufacturing a fuel tank (10) for a motor vehicle according to claim 13, in which step e) of fixing the at least one bladder (1) inside the fuel tank (10) is carried out by means of clipping (8), snapping, nesting, gluing, clamping, pinching or welding the at least one bladder (1) on an internal wall of the fuel tank (10).
  15. Method of manufacturing by extrusion blow molding a fuel tank (10) for a motor vehicle according to claim 10, comprising the following steps: a) having at least one bladder (1) according to any one of claims 1 to 8, b) opening an extrusion blow mold and extruding a parison into the open mold, c) introducing by means of an insertion rod the at least one bladder (1) inside the parison, d) bringing the extrusion blow mold into an intermediate closed position in order to fix the at least one bladder (1) inside the parison by pressing the parison either against the at least one bladder (1) or against a protective casing (6) of the at least one bladder (1), e) remove the insertion rod, f) bringing the extrusion blow mold into a final closing position in order to preform a fuel tank, (g) introducing a pressurized gas into the extrusion blow mold to form the fuel tank by blow molding, h) open the extrusion blow mold and remove the fuel tank thus formed.

Description

fuel tank bladder Technical field of the invention Technical background of the invention The present invention relates generally to the control of the pressure of fuel vapors in a fuel tank for a motor vehicle, in particular for a hybrid vehicle. A hybrid vehicle is a vehicle equipped with a heat engine (also called an "internal combustion engine") combined with one or more electric motors. The term "motor vehicle" means any mobile equipment, in particular, vehicles on road, rail, sea, air, space. More particularly, the invention relates to a bladder for a fuel tank for a motor vehicle. The invention also relates to an assembly comprising a protective casing and a bladder according to the invention. The invention also relates to a fuel tank for a motor vehicle comprising at least one bladder according to the invention. The invention also relates to a fuel tank for a motor vehicle comprising at least one assembly according to the invention. The invention also relates to a use of at least one bladder according to the invention in a fuel tank for a motor vehicle. The invention also relates to a motor vehicle, in particular a hybrid vehicle, comprising a fuel tank according to the invention. The invention also relates to a method of manufacturing a fuel tank for a motor vehicle comprising at least one bladder according to the invention. The invention also relates to a method of manufacturing by extrusion blow molding a fuel tank for a motor vehicle comprising at least one bladder according to the invention. The invention finally relates to a method of operating a fuel tank according to the invention. The fuel stored in a fuel tank for a motor vehicle is subject to temperature fluctuations that depend mainly on the outside temperature. Depending on the climate to which the vehicle is exposed, the temperature of the fuel can vary greatly, particularly if the vehicle is outside when it is moving and when it is parked. An increase in the temperature of the fuel stored in the fuel tank generates an evaporation of a quantity of it. Given that the fuel tank defines a predetermined, closed and sealed volume, the generation of fuel vapors causes an increase in pressure in the gas phase inside the fuel tank. High fuel vapor pressure generates mechanical stresses on the walls of the fuel tank, which can damage them or even constitute a risk of explosion of the fuel tank if the increase in pressure is not controlled. It is known in the prior art, for example from document WO 2021/013940 A1, to place a bellows inside a fuel tank. This bellows is connected to an air inlet and outlet duct leaving the fuel tank and makes it possible, alternately, to supply the bellows with air or to evacuate part of the air contained in the bellows. In this way, depending on the fluctuation in the quantity of fuel vapors present in the fuel tank, the bellows can compress or decompress to modify the volume available for the fuel vapors and thus limit the variations in fuel vapor pressure. This bellows system does indeed reduce the risk of pressure peaks in the fuel tank, but it does pose certain problems. Indeed, the Applicant has found that a bellows with a cylindrical external shape must have a relatively large diameter to be effective. However, the larger the diameter of the bellows, the more complex it becomes to introduce and fix it in the fuel tank. Complex manufacturing of the fuel tank implies an increase in the cost and manufacturing time of the fuel tank, which is not desirable. Furthermore, a bellows having identical folds does not behave in a predictable manner when the bellows is compressed. Indeed, the Applicant has observed the appearance of buckling of the folds when a bellows having identical folds is compressed. Due to this uncontrolled buckling, the geometry of the compressed bellows differs from one compression to another, which is not desirable. Document DE 10 2018 203006 A1 describes a bladder defining a variable volume sealed enclosure for a fuel tank in which the sealed enclosure comprises a compressible bellows, said bellows comprising a set of folds, the folds of said set of folds not all being identical to each other. The invention aims in particular to solve the problems identified in the state of the art by limiting the rise in pressure of fuel vapors in the fuel tank while avoiding or reducing the drawbacks posed by the bladder of the state of the art. For this purpose, the invention relates to a bladder defining a variable-volume sealed enclosure for a fuel tank, in which the sealed enclosure comprises a compressible bellows in a Z-axis direction, said bellows comprising a set E1 of folds, the folds of said set E1 of folds not all being identical to each other, characterized in that each fold of a subset E2 of folds of the set E1 of folds has the shape of a flat and closed elongated ring when it is projected orthogonally on an XY plane perpendicular to the Z axis, said ring having an external length L ext. and an