WO2020174161A1

WO2020174161A1 - Bumper structure subassembly comprising a damper element associated with an impact sensor

Info

Publication number: WO2020174161A1
Application number: PCT/FR2020/050318
Authority: WO
Inventors: Clement Jeanneau; Alain VALTIER; Marc Peru; Ludovic Meresse
Original assignee: Psa Automobiles Sa
Priority date: 2019-02-25
Filing date: 2020-02-20
Publication date: 2020-09-03
Also published as: CN113474222A; FR3093046A1; EP3931049A1; FR3093046B1

Abstract

The invention relates to a bumper structure subassembly comprising a damper element (30) intended to be installed longitudinally between a bumper fascia (10) and the transverse beam (21) of a bumper reinforcement (20); an impact sensor (40) comprising an elastically deformable tube (41); and two pressure sensors (42) installed at the two ends of said tube (41) and able to detect the pressure variations within the latter, said tube (41) comprising at least one main section (41A) housed in a transverse groove (31) formed in the rear face (30A) of said damper element (30); characterized in that said tube (41) comprises two end sections (41B) extending transversely on either side of said main section (41A) and being accommodated in two respective cavities formed within the two lateral end portions (30B) of said damper element (30) extending transversely on either side of said groove (31).

Description

DESCRIPTION

Title of the invention: Subassembly of a bumper structure comprising a damping element associated with an impact sensor

Technical area

The present invention claims the priority of the French application 1901863 filed on February 25, 2019, the content of which (text, drawings and claims) is incorporated here by reference.

The present invention relates to a bumper structure sub-assembly comprising a damping element associated with an impact sensor. It also relates to a bumper structure comprising such a sub-assembly.

Prior art

Regulatory changes in the automotive field tend more and more to limit the aggressiveness of vehicles vis-à-vis other road users, and in particular pedestrians.

Motor vehicles must thus be able to provide satisfactory responses to impacts occurring at the front bumper of these vehicles while exhibiting different zones and impact forces, such as for example pedestrian impacts and corresponding reparability impacts. at a meeting of a side part of this bumper with a rigid obstacle at a certain speed, often less than 20km / h.

In the event of an impact of a pedestrian with the front bumper of a motor vehicle, it is necessary to limit the bodily injury of this pedestrian to his legs, to absorb the kinetic energy of such a light impact and limited, which is reflected, in general, in terms of the architecture of the vehicle, by the addition of a foam damping element implanted longitudinally between the bumper trim and the transverse beam of the metal bumper reinforcement. shocks.

In addition, during such an impact, the pedestrian tends to be thrown towards the hood of the vehicle: his femur hitting the front part of this hood while that its head impacts an area between the middle and the rear of this cover.

In order to absorb the kinetic energy of this second impact, the cover is made of a material capable of deforming under the effect of this impact.

The engine compartment of certain types of vehicles (in particular, sedans) being highly encumbered by rigid components such as in particular the powertrain and the radiator, the distance between them and the bonnet proves insufficient to allow this last to deform sufficiently and absorb this impact.

In order to overcome this problem, it is known to provide on this type of vehicle, means capable of automatically raising the hood in the event of detection of a collision of a pedestrian with the front bumper by means of a specific impact sensor connected to an electronic control unit

Such an impact sensor, described in the international application WO 2012/113362 A1, comprises an elastically deformable hollow flexible tube housed in a groove made on the rear face of the damping element, as well as two pressure sensors located at both ends. of this tube and capable of detecting the pressure variations inside the latter caused by the deformation of this damping element during an impact between a body and the front bumper of the vehicle.

The analysis of the signals transmitted by these sensors allows an electronic control unit to determine the type of collision that has just occurred and thus to control the lifting of the hood in the event of a collision with a pedestrian.

Unfortunately, in the event of a repairable impact, the side end of the bumper reinforcement beam tends to shear the tube which requires the complete replacement of the impact sensor, the relatively high cost of which can represent up to 5%. of the total cost of repairing damage caused by such a shock.

Disclosure of the invention

The present invention therefore aims to improve the situation. For this purpose, it proposes a sub-assembly of a bumper structure for a motor vehicle comprising a damping element intended to be installed longitudinally between a bumper cover and the transverse beam of a bumper reinforcement, as well as an impact sensor comprising an elastically deformable tube as well as two pressure sensors located at both ends of said tube and capable of detecting pressure variations inside the latter, said tube comprising at least one main section housed in a groove transverse provided on the rear face of said damping element; characterized in that said tube comprises two end sections extending transversely on either side of said main section and being housed in two respective cavities formed inside the two lateral end portions of said damping element extending transversely on either side of said groove.

Such an arrangement makes it possible to prevent the ends of the beam, intended to be positioned opposite the two lateral end portions of the damping element, from coming into direct contact with the tube in the event of a reparability impact. , so as to prevent any shearing of the latter.

Following such an impact, the undamaged impact sensor 40 can thus be reassembled on a new damping element 30, which makes it possible to significantly reduce the amount of repair costs.

According to preferred characteristics of said subset, taken alone or in combination:

said pressure sensors are also housed inside said cavities;

said cavities are covered with a material thickness of at least 20 mm;

said material thickness is between 30 and 40 mm;

said cavities have a section profile corresponding substantially to that of said pressure sensors;

said damping element consists of a block of expanded polypropylene foam having a density of between 20 and 80 kg / m ³ ; and or said tube has a circular annular section, the thickness of which is between 0.8 and 1.2 mm.

The invention also relates in a second aspect to a bumper structure for a motor vehicle comprising a bumper cover, a bumper reinforcement comprising a transverse beam, and such a sub-assembly of which the damping element is implanted longitudinally. between said bumper cover and said beam.

According to a preferred characteristic of said bumper structure, said damper element extends transversely over a length intermediate those of said covering and of said beam, said groove extending transversely over a length less than that of said beam so that each end of this groove is spaced transversely from the corresponding end of said beam by a predetermined distance

Advantageously, this predetermined distance is between 10 and 40 mm.

Brief description of the drawings

The description of the invention will now be continued with the detailed description of an exemplary embodiment, given below by way of illustration but not limitation, with reference to the appended drawings, in which:

[Fig 1] is a view of the front bumper structure of a motor vehicle according to the invention;

[Fig 2] shows an enlarged sectional view of the subassembly consisting of the damping element and the impact sensor, taken at the level of the main section of the tube housed in a groove made on the rear face of the damping element;

[Fig 3] is an enlarged sectional view of the sub-assembly of Figure 2, taken at an end section of the tube housed in a cavity formed inside a corresponding end portion of the tube. damping element; and

[Fig 4] shows an enlarged sectional view of the sub-assembly of Figure 2, taken at the level of a pressure sensor housed in a cavity formed inside a corresponding end portion of the damping element.

detailed description

An orthogonal frame XYZ comprising three perpendicular axes two by two, namely:

an axis X, defining a longitudinal, horizontal direction coinciding with the general direction of movement of the vehicle;

a Y axis, defining a transverse, horizontal direction, which together with the X axis defines a horizontal XY plane, and

a Z axis, defining a vertical direction, perpendicular to the horizontal XY plane.

In the description which will follow and by convention, the terms “front” and “rear” will be used to define the relative position of an element with respect to another according to the general direction of movement of the vehicle.

Figure 1 shows a front bumper structure 1 of a motor vehicle, comprising a bumper cover 10 forming the front end of the vehicle, a bumper reinforcement 20 constituting the front end of the vehicle frame , and a damping element 30 located longitudinally between the bumper cover 10 and the bumper reinforcement 20.

Produced from a thin metal sheet or from a molded plastic resin, the bumper trim 10 extends over the entire width of the vehicle while being secured to the body of the vehicle by means of several points of fixing not shown.

The bumper reinforcement 20 consists essentially of a hollow metal beam 21 extending transversely over a length less than that of the bumper cover 20, and of two identical metal side absorbers 22, each secured to each other. a corresponding side end portion of the beam 21, these absorbers being intended to be fixed to the front ends of the two side sills of the vehicle. Conventionally obtained by forming or extrusion, the beam 21 is designed to transmit to the side absorbers the forces undergone during an impact with the front of the vehicle. It may include internal reinforcing metal plates extending transversely and intended to improve its mechanical strength.

Equipped with lower mechanical rigidity than those of the beam 21 and the side rails of the vehicle, the two side absorbers 22 are provided, in the event of a reparable impact, to crash and thus absorb the energy of this shock so as to avoid any deterioration of these side stretchers.

Made up of a block of polyurethane, polypropylene or expanded polystyrene foam, the damping element 30 has a lower mechanical rigidity than that of the bumper reinforcement 20 (and in particular that of its two side absorbers 22).

The damping element 30 is advantageously made of a block of expanded polypropylene foam having a density of between 20 and 80 kg / m ³ .

In the event of a pedestrian impact, this damping element 30 is designed to crash and thus absorb the energy of this impact so as to avoid any deterioration of the bumper reinforcement 20.

As illustrated in Figure 1, the damping element 30 extends transversely over a length intermediate between that of the bumper cover 10 and that of the beam 21 of the bumper reinforcement 20, from which it extends transversely on both sides.

Referring to Figure 2, it can be seen that this damping element 30 has a groove 31 formed on its rear face 30A and extending transversely over a length slightly less than that of the beam 21 of the bumper reinforcement 20.

The bumper structure 1 also comprises an impact sensor 40 comprising an elastically deformable tube 41, as well as two pressure sensors 42 located at the two ends of this tube 41 and capable of detecting the pressure variations inside. the latter caused by the deformation of this damping element 30 upon impact between a body and the front bumper of the vehicle. These two pressure sensors 42 are intended to be electrically connected to an electronic control unit, not shown. When a front impact occurs, the analysis of the signals transmitted by the two pressure sensors 42 as well as by other sensors (such as an impact speed sensor) allows this control unit to determine the type of body (for example, a pedestrian or an object such as a post or a low wall) with which the vehicle has just collided. In the event of a pedestrian impact being detected, the control unit is thus able to trigger a device for automatically lifting the vehicle hood allowing the latter, in the event of a second impact with the pedestrian's head, to deform sufficiently to ensure efficient absorption of the kinetic energy of this impact.

Constituted advantageously of crosslinked silicone, the tube 41 has a circular annular section, substantially homogeneous over its entire length and the thickness of which is advantageously between 0.8 and 1.2 mm.

Preferably, this tube 41 has an internal diameter of between 7 and 9 mm and an external diameter of between 9 and 11 mm.

As illustrated in Figures 1 and 2, the main section 41A of the tube 41 is housed in a groove 31 formed on the rear face 30A of the damping element 30 and extending transversely over a length less than that of the beam 21 of the bumper reinforcement 20 so that each end of this groove 31 is spaced transversely from the corresponding end of the beam 21 by a predetermined distance, advantageously between 10 and 40 mm.

The groove 31 has a U-shaped section, the semicircular bottom of which is turned towards the rear and the width of which is very slightly greater than the outer diameter of the tube 41.

Referring to Figures 1 and 3, it can be seen that the two end sections 41 B of the tube 41 extending transversely on either side of its main section 41A housed in the groove 31 are housed in two respective cavities 32 formed inside the two lateral end portions 30B of the damping element 30 extending transversely on either side of the groove 31. Such an arrangement makes it possible to prevent the ends of the beam 21 from coming into direct contact with the tube 41 in the event of a reparability impact, so as to prevent any shearing of the latter.

Thus, following such an impact, the undamaged impact sensor 40 can be reassembled on a new damping element 30, which makes it possible to significantly reduce the amount of repair costs.

The cavities 42 advantageously have a section profile corresponding substantially to that of the sensors, so as to allow, when mounting the impact sensor 40 on the damping element 30, easy insertion by an operator of each of the pressure sensors 42. through the corresponding cavity 42.

In order to obtain optimum protection, the cavities 32 formed inside the two lateral end portions 30B of the damping element 30 are covered with a material thickness (ie foam) of at least 20 mm and preferably between 30 and 40 mm. Moreover, and in order to avoid having discontinuities in coverage at the junctions between the ends of the tube 41 and the two pressure sensors 42 (these discontinuities being able to constitute areas of weakness in the event of reparability shock), these two pressure sensors 42 are also advantageously housed inside the two cavities 32 formed inside the two lateral end portions 30B of the damping element 30.

According to variant embodiments not shown, the characteristics of the tube of the impact sensor and / or those of the damping element are different.

In general, it is recalled that the present invention is not limited to the embodiments described and shown, but that it encompasses any variant execution within the reach of a person skilled in the art.

Claims

1. Sub-assembly of a bumper structure for a motor vehicle comprising a damping element (30) intended to be implanted longitudinally between a bumper cover (10) and the transverse beam (21) of a bumper reinforcement. shocks (20), as well as an impact sensor (40) comprising an elastically deformable tube (41) as well as two pressure sensors (42) located at both ends of said tube (41) and able to detect pressure variations inside the latter, said tube (41) comprising at least one main section (41A) housed in a transverse groove (31) made on the rear face (30A) of said damping element (30); characterized in that said tube (41) comprises two end sections (41B) extending transversely on either side of said main section (41A) and being housed in two respective cavities (32) formed inside the two end lateral portions (30B) of said damping element (30) extending transversely on either side of said groove (31).

2. Subassembly of a bumper structure according to claim 1, characterized in that said pressure sensors (42) are also housed inside said cavities (32).

3. A bumper structure sub-assembly according to one of claims 1 or 2, characterized in that said cavities (32) are covered with a material thickness of at least 20 mm.

4. A bumper structure sub-assembly according to claim 3, characterized in that said material thickness is between 30 and 40 mm.

5. A bumper structure sub-assembly according to one of claims 1 to 4, characterized in that said cavities (32) have a section profile corresponding substantially to that of said pressure sensors (42).

6. A bumper structure sub-assembly according to one of claims 1 to 5, characterized in that said damping element (30) consists of a block of expanded polypropylene foam having a density of between 20 and 80 kg / m ³ .

7. A bumper structure sub-assembly according to one of claims 1 to 6, characterized in that said tube (41) has a circular annular section, the thickness of which is between 0.8 and 1.2 mm. .

8. A bumper structure for a motor vehicle comprising a bumper cover (10), a bumper reinforcement (20) comprising a transverse beam (21), and a sub-assembly according to one of claims 1 to 7, the damping element (30) of which is located longitudinally between said bumper cover (10) and said beam (21).

9. A bumper structure for a motor vehicle according to claim 8, characterized in that said damping element (30) extends transversely over a length intermediate between those of said trim (10) and of said beam (21), and in that said groove (31) extends transversely over a length less than that of said beam (21) so that each end of this groove (31) is transversely spaced from the corresponding end of said beam (21) of a predetermined distance.

10. A bumper structure for a motor vehicle according to claim 9, characterized in that said predetermined distance is between 10 and 40 mm.