CROSS-REFERENCE TO RELATED APPLICATIONS

This application is the US National Stage under 35 USC § 371 of International Application PCT/FR2020/050190 filed 5 Feb. 2020 which claims priority to French Application No. 1902308 filed 7 Mar. 2019, both of which are incorporated herein by reference.

BACKGROUND

The invention relates to a motor vehicle equipped with an impact protection device for underfloor elements.

In particular, the invention relates to a rear impact protection device for the traction battery mounted in front of the exhaust muffler under the floor of hybrid vehicles.

Motor vehicles are generally equipped with a muffler, which is mounted on the exhaust line under the floor and at the rear of the vehicle.

On certain vehicles, and in particular on plug-in hybrid vehicles (PHEV type), this muffler is mounted behind the traction battery. The muffler and the battery are separated by an intermediate heat shield that ensures the protection of the battery from heat radiation emanating from the muffler.

In the event of a collision, or more generally of an impact at the rear of the vehicle, the muffler is then deformed and/or suddenly moved forward. Since the heat shield generally only consists of a sheet or a thin metal sheet, it cannot prevent the muffler from directly impacting the battery and damaging it severely by generating electrical risks (fire, explosion, etc.).

However, the option of avoiding contact between the muffler and the battery by moving the muffler away is not possible on vehicles with a short overhang.

Another option would be to have a protective frame around the battery, but this solution would weigh down the battery and be excessively expensive.

There are already devices for protecting on-board elements against impacts under the floor of motor vehicles, such as that described in FR3036359. However, this device, which also provides thermal protection, is only intended to protect the tank of the selective catalytic reduction (SCR) system during any direct and vertical contact with the ground, and not from an impact to the rear of the vehicle oriented in a longitudinal direction.

In this context, it has proved necessary to provide new means that are specifically adapted to ensure the mechanical protection of the underfloor elements and, in particular, of the battery in the event of a collision at the rear of the vehicle while respecting compactness and lightness constraints as well as reasonable manufacturing and assembly costs.

SUMMARY

The object is to resolve the technical problems posed by the prior art by proposing to furnish the heat insulating shield with a damping element making it possible to preserve the integrity of the battery during an impact at the rear of the vehicle.

This object is achieved by means of a motor vehicle equipped with an impact protection device for a battery mounted under the floor of said vehicle and separated from an exhaust muffler by an intermediate heat shield, wherein said device comprises a cushion fastened opposite the battery on said heat shield, said cushion being able to deform when the muffler moves toward and contacts the battery, in order to absorb the kinetic energy resulting from an impact on said vehicle.

According to one advantageous feature, the cushion has a larger surface than the face of the battery situated opposite it.

According to another feature, the cushion extends at least over the height of the portion projecting toward the front of the exhaust muffler.

According to an alternative embodiment, the cushion has an extra thickness of between 0.5 and 2.0 cm opposite the portion projecting toward the front of the exhaust muffler.

According to another alternative, the cushion has a uniform thickness of between 0.5 and 2.0 cm.

Preferably, the cushion extends over the entire height of the front face of the exhaust muffler.

According to yet another feature, the cushion is made of a deformable material, the relative density (or specific gravity) of which is between 0.1 and 0.65.

According to another alternative, the cushion is fastened to the front face of the heat shield by gluing.

According to yet another alternative, the cushion and the heat shield are made in one piece.

Another object is a hybrid vehicle equipped with a device having the features mentioned above for the impact protection of the traction battery mounted in front of the muffler, said cushion being intended to absorb the kinetic energy resulting from an impact at the rear of said vehicle.

The invention thus is comprised of using the existing heat shield, in integrating a mechanical protection function with the heat shield, and in positioning the protection device in the most judicious place, that is to say, between the battery and the muffler, which makes it possible not to add a step for assembling additional elements under the vehicle floor.

The protection device equipping the vehicle is simple, reliable and economical because it makes it possible to preserve the integrity of the battery during an impact or a collision at the rear of the vehicle in an efficient manner without it being necessary to provide additional heavy and complex structural means and without modifying the assembly method.

At the time of impact, the cushion comes into contact with the battery over a large area in order to reduce local stresses. Then following the impact, the cushion absorbs the kinetic energy and diffuses it over a large surface, thus avoiding local deformation and the risk of tearing the battery casing.

