FR3038561A1 - IMPACT ABSORPTION SYSTEM FOR CONSUMABLE FLUID RESERVOIR - Google Patents

Abstract

The invention relates primarily to a sub-floor assembly (10) of a motor vehicle comprising: - a rear crossmember (3) - a consumable fluid reservoir (2), and - a travel zone (Z) corresponding to the zone in which the reservoir (2) can move relative to the rear crossmember (3) in the event of impact, characterized in that said assembly further comprises a shock absorption system (1) located in said travel zone (Z) for absorbing at least partly a kinetic energy of said reservoir (2) in motion during a shock.

Description

IMPACT ABSORPTION SYSTEM FOR TANK

CONSUMABLE FLUID

The invention relates to a shock absorbing system for consumable fluid reservoir, in particular fuel or reactive liquid for example for the cleanup of exhaust gases, the ammonia precursor type as the urea in particular aqueous phase and the corresponding motor vehicle. For the sake of conciseness, we will speak rather of the example of the fuel tank, although the invention is therefore also applicable to tanks for other fluids.

During a frontal impact and more particularly during a collision between two vehicles or during approvals consisting for example in launching a vehicle on a rigid wall at a predetermined speed, the fuel tank must be damped in order to limit its movement in the vehicle, as well as the risk of fuel leakage.

In order to limit the displacement of the tank during an impact, it is possible to use means for fixing the tank to its body structure, as disclosed by US7758075.

To dissipate the energy of the shock, the document FR3004388 teaches the realization of tanks having a lower wall having on its surface ribs dissipating the energy of the impact between the reservoir and the soil by deformation of the ribs.

There are also tank walls provided with antivibration elements to absorb the vibrations of the tank as described in EP 2 033 829. However, these antivibration elements are only designed for acoustic purposes to avoid noise and noise. are not suitable for holding the tank in case of impact.

Document FR 2 794 406 proposes a device for absorbing kinetic energy produced by a shock on the reservoir. However, to use such a device, the entire structure of the reservoir needs to be modified so that it has on its surface cavities in which are housed complementary form of absorption devices.

The invention aims to effectively remedy at least one of the aforementioned drawbacks by providing a sub-floor assembly of a motor vehicle comprising: - a rear crossmember - a consumable fluid reservoir, for example fuel, and - a deflection zone corresponding to the zone in which the fuel tank can move relative to the rear cross member in the event of impact, such that said assembly further comprises a shock absorption system located in said deflection zone to absorb at the less in part a kinetic energy of said tank in motion during a shock.

The consumable fluid is preferably in the liquid phase.

It may be fuel or any reactive liquid, especially used in the treatment of exhaust gas, such as urea in the aqueous phase.

The invention thus limits a displacement of the tank in the vehicle to prevent the inertia of the tank due to shock tears the fastening means between the tank and the vehicle, or that these fastening means exert too much effort. tank may cause a tear in its envelope. In addition, because of the installation of the reported shock absorption system, the invention is easily adaptable to existing tanks.

In one embodiment, said shock absorbing system is adapted to deform to limit a displacement of said reservoir in case of shock.

In one embodiment, said shock absorbing system is attached to a structural element, such as the tank, said rear cross member or a body reinforcement.

According to one embodiment, said reservoir is attached to the vehicle by means of fixing means. The invention thus makes it possible to limit the forces applied by said fastening means on said tank during an impact.

In one embodiment, the fixing means comprise fixing lugs.

In one embodiment, the fastening means comprise fastening straps.

In one embodiment, said fuel tank is positioned in a tier two zone located under the seats of the rear passengers of the vehicle.

According to one embodiment, said shock absorption system is made of a material based on metal or metal alloy or polymer (s). The polymers can be strengthened. It may be for example, metal, rubber, plastic or elastomeric material. Plastics of the rigid type can be mentioned, such as polymers of the family of polyamides or of ABS (for acrylonitrile butadiene styrene), and plastic materials of the flexible type of PE type (polyethylene) such as HDPE (high density polyethylene). .

The invention also relates to a motor vehicle comprising a sub-floor assembly according to the invention.

The invention will be better understood on reading the description which follows and the examination of the figures that accompany it. These figures are given for illustrative but not limiting of the invention.

Figure 1 is a side perspective view of a subfloor assembly according to the present invention; Figure 2 is a bottom view of a subfloor assembly according to the present invention; Figure 3 is a graphical representation of the acceleration experienced by a reservoir during a frontal impact; Figure 4 is a graphical representation of the displacement undergone by a tank with or without shock absorption system during a frontal impact; Figures 5a, 5b and 5c are perspective views of a tank without shock absorption system respectively of the left side before impact, the left side after shock and the right side after shock; Figures 6a and 6b are perspective views after simulation of a frontal impact of a fastening lug of a tank respectively without shock absorption system and with shock absorption system.

Identical, similar or similar elements retain the same reference from one figure to another.

[0027] Figure 1 shows a sub-floor assembly 10 comprising a rear cross member 3 and a fuel tank 2. The tank 2 is positioned for example in a tier two area located under the rear passenger seats.

The tank 2 may be attached to the vehicle with the fixing lugs 20 and at least one fastening strap 21 clearly visible in Figure 2. In the embodiment, the fastening lugs 20 located at the corners of the tank 2 are made of material with the tank 2 and have openings allowing the passage of a screw-type fastener or rivet to secure the tank 2 to the floor of the vehicle.

Furthermore, the fastening strap 21 cooperates with a recess formed in the lower face of the tank 2 and has a first end attached to the cross member 3 and a second end attached to an underfloor element located on the side opposite the cross member. 3. For this purpose, each end may have at least one opening allowing the passage of a fastener of corresponding shape, such as a screw or a rivet. The means 20, 21 thus make it possible to hold the tank 2 in position and to limit its displacement in the direction of the cross member 3 in the event of an impact.

In addition, a clearance zone Z extends between the tank 2 and the crossbar 3. This zone Z corresponds to the area in which the tank 2 can move relative to the rear cross member 3 in case of impact, especially during a frontal impact.

A shock absorbing system 1 is located in the deflection zone Z to absorb at least partly the kinetic energy of the reservoir 2 in motion during an impact and therefore to limit the displacement of the reservoir 2 towards the 3. The shock absorbing system 1 may be attached either to the tank 2, or to the rear cross beam 3, or a box reinforcement, or on the body, or on any other structural element. Alternatively, it is possible to use several shock absorption systems 1, for example two systems 1, each attached to a different structural element.

The shock absorbing system 1 is preferably made of a material capable of absorbing shocks and reducing the inertia of the reservoir 2 to avoid tearing the fastening means 20, 21. Preferably, the shock absorption system 1 is made of a compressible material. Without limitation, the choice of material may be made from one or more of the following materials: hard or soft plastic, metal, rubber, or elastomeric material. In a particular embodiment, the shock absorption system 1 has a thickness of the order of 50mm.

The total displacement of the reservoir 2 corresponding to the sum of the deflection of the fastening means 20, 21 and the deformation of the reservoir 2, the shock absorption system 1 is preferably located at a location of greater deflection by relative to the rear cross member 3 while bearing on a sufficiently large surface of the shell of the tank 2 to distribute all the constraints.

Figure 3 shows the acceleration curve undergone by the fuel tank 2 during a frontal impact. During this shock occurring for example during a certification on a rigid wall, the vehicle crashes on the wall and the tank 2 continues to advance towards the rear cross member 3 because of its kinetic energy, and although is held under the floor of the vehicle by the fixing means 20, 21.

The graph of FIG. 4 compares the displacement of the reservoir 2 during a frontal impact in the presence of an absorption system 1, curve C1, or without absorption system 1, curve C2. It should be noted that the displacement of the tank 2 is reduced in the presence of the shock absorption system 1. In addition, it appears that for a tank 2 without a shock absorption system 1, the fastening means 20, 21 deform excessively up to the detachment of the reservoir 2, which causes the presence of several tears 4 at the fastening means 20, 21 (see Figures 5a, 5b, 5c, and 6a). This is due to the inertia of the tank 2 mainly related to the mass of the fuel creating a deformation of the shell of the tank 2.

In contrast, for a tank 2 having suffered a frontal impact in the presence of the absorption system 1, we note that the bracket 20 has undergone a reduced deformation and remains attached to the tank 2. In addition, the tears 4 are less important than without shock absorption system 1. Thus, the shock absorption system 1 prevents the kinetic energy or the inertia of the tank 2 due to the shock tears the fastening means 20, 21 from tank 2 to the vehicle, which at the same time makes it possible to limit its movement towards the rear cross member 3 and the vehicle.

Claims (10)

1. sub-floor assembly (10) of a motor vehicle comprising: - a rear crossmember (3) - a consumable fluid reservoir (2), and - a deflection zone (Z) corresponding to the zone in which the reservoir (2) can move relative to the rear cross member (3) in the event of impact, characterized in that said assembly further comprises a shock absorption system (1) located in said travel zone (Z) to absorb at least partly a kinetic energy of said reservoir (2) in motion during an impact. 2. Subfloor assembly according to claim 1, characterized in that said shock absorbing system (1) is able to deform to limit a displacement of said tank (2) in case of impact. 3. Sub-floor assembly according to claim 1 or 2, characterized in that said shock absorbing system (1) is attached to a structural element, such as the tank (2), said rear cross member (3) or a cashier reinforcement. 4. Subfloor assembly according to any one of claims 1 to 3, characterized in that said reservoir (2) is fixed to the vehicle by means of fixing means (20, 21). 5. Subfloor assembly according to claim 4, characterized in that the fastening means comprise fixing lugs (20). 6. Subfloor assembly according to claim 4 or 5, characterized in that the fastening means comprise fastening straps (21). 7. Subfloor assembly according to any one of the preceding claims, characterized in that said reservoir (2) is positioned in a tier two zone located under the seats of the rear passengers of the vehicle. 8. subfloor assembly according to any one of the preceding claims, characterized in that said shock absorption system (1) is made of a material based on metal or metal alloy, or polymer (s) . 9. Subfloor assembly according to one of the preceding claims, characterized in that the reservoir is a fuel tank or reactive liquid, including an exhaust gas treatment reagent. 10. A motor vehicle characterized in that it comprises a sub-floor assembly as defined in any one of the preceding claims.