BACKGROUND

The present disclosure relates to a bumper which comprises a bumper crossmember having an outer shell and having at least one sensor holder arranged therein, and an outer cladding shell.

Motor vehicles have front and rear bumpers. These serve to absorb impacts up to a certain strength without the rest of the vehicle body taking damage. Modern bumpers comprise a bumper crossmember which is supported on the body side, typically on the side members, by energy-absorbing crash elements, so-called crash boxes. The bumper crossmember is faced, for front and rear termination of the vehicle, with an outer skin, typically a cladding shell made from a plastic material. The bumper crossmember serves to distribute the impact energy across the width of the vehicle and thus to discharge the impact energy into crash elements which are spaced from one another.

Sensors are generally housed in a cladding shell of a bumper. In particular, close-range distance measurement sensors for use in conjunction with a parking assistance system are a typical component of such cladding shells. Such close-range distance measurement sensors are also referred to as parking sensors. These parking sensors are held on the outer cladding shell, and their sensor head engages with a corresponding recess in the outer cladding shell. There is typically a certain distance between the facing shell and the bumper crossmember. In order not to have to enlarge the gap between the outer cladding shell and the bumper crossmember in the event of mounting of sensors, for example parking sensors, on the bumper, through-holes are introduced into the bumper crossmember as sensor holders. The sensors carried by the cladding shell dip into said holes. Such a through-hole is required in order to provide sufficient space in order to be able to introduce an electrical connection cable onto the connector on the rear termination of the sensor located opposite the sensor head.

In order to achieve the necessary rigidity while at the same time achieving cost-effective manufacturing of such a bumper crossmember, this is typically constructed with a double-shell structure, i.e. with an outer shell and an inner shell which are arranged one in front of the other in the direction of travel of the vehicle. In this manner, the bumper crossmember forms a hollow-chamber profile which runs transverse to the direction of travel. The through-holes for the provision of a sensor holder are introduced into the outer shell. Through the introduction of through-holes to provide the necessary sensor holders, the outer shell and thus the bumper crossmember as a whole is weakened at the sites of the through-holes, which can result in unwanted buckling of the bumper crossmember under an impact which should be absorbed. This is compensated for through the use of an outer shell with adequately greater material thickness. However, this increases the weight of the bumper crossmember. The problem outlined above occurs in particular when such a bumper is to carry more than just one or two sensors and/or has a single-shell, particularly hat-shaped, design and is arranged open in the vehicle direction.

In addition to the bumpers described above, bumpers in which the sensors are arranged and held on the bumper crossmember are also known. The problem with such a design is that the sensor heads of the sensors are at a distance from the outer cladding shell and are covered by it. The sensor data is proportionally less accurate, for example if the sensors are ultrasound sensors within the context of a parking assistance system. These types of bumper designs are known from DE 10 2014 009 941 A1 or DE 10 2013 006 365 A1, for example.

SUMMARY

Proceeding from this background, an aspect of the present disclosure is therefore to develop a bumper of the type specified at the beginning such that, regardless of the number of sensors that the thus-equipped bumper is to carry, an increase in weight which accompanies an increase in the number of sensors is avoided.

According to the present disclosure, this is solved through a bumper comprising a bumper crossmember having an outer shell and at least one sensor holder arranged therein, and an outer cladding shell, in which the at least one sensor holder is implemented as an impressed pocket originating from the front-side termination of the outer shell and having an upper wall, a lower wall and a base connecting the two walls, and the outer cladding shell carries at least one sensor engaging in the sensor holder on the side of the outer cladding shell pointing towards the bumper crossmember in the region of a sensor holder.

In contrast to the prior art discussed above, the sensor holders in the bumper crossmember are designed in this bumper not as through-holes, but rather as impressed pockets towards the vehicle and thus in the x direction of the axial direction of the vehicle. These pockets have an upper wall, a lower wall and a base connecting the two walls. The two walls are spaced from one another in the z direction. In contrast to bumper crossmembers in the state of the art, such a recess in the outer shell of the bumper crossmember does not weaken it and thus the entire bumper crossmember, but rather the opposite is true: this measure stiffens the outer shell. A bumper which comprises such a bumper crossmember can therefore also have multiple sensor holders without the outer shell of the bumper crossmember needing to be designed with greater material thickness in order to ensure the desired stiffness. Owing to the structures introduced into the bumper crossmember by the impressed sensor holders, its stiffness is increased not only against buckling, but also against torsion strains. For this reason, the bumper crossmember according to this concept can therefore even sometimes be designed with a reduced material thickness with regard to its outer shell. The impressions act as a form of stiffening beading. Owing to the stiffening effect of the pocket-like sensor holders, it is sometimes even possible to forego the use of a second shell to achieve the same stiffness of the bumper crossmember owing to the at least one stiffening embossment relating thereto.

It is nevertheless also possible to design the bumper crossmember of such a bumper as a double-shelled structure with an outer shell and an inner shell.

The two shells are connected to one another to form a hollow-chamber profile, through welding of connection flanges which lie next to each other for example.

The sensor holders in the bumper crossmember are preferably designed such that they also comprise a right-hand and left-hand side wall in addition to the upper wall, the lower wall and the base connecting the two walls. These side walls, as well as the upper and lower walls, may be angled toward each other, wherein the cross-sectional area tapers towards the base of the sensor holder.

The at least one sensor holder may be arranged in a bead which is integrated into the longitudinal extension of the outer shell in the direction of the inner shell. If this bead is sufficiently deep for the sensor holder, then the sensor holder provided by the bead does not necessarily need to have a right-hand and left-hand side wall. If the depth of such a bead is insufficient to serve as a sensor holder, then the depth of the same is increased in the region of the sensor holder formed as an impressed pocket such that, as with an arrangement of the sensor holder outside such a bead, the sensor holder also has a right-hand and a left-hand wall. These walls are angled towards the base of the sensor holder. If an outer shell of the bumper crossmember with bead which follows the longitudinal extension of the latter, impressed towards the rear shell, is envisaged, then further stiffening of the same may be effected through making the height reached by the bead in the direction of the vertical extension of the bumper crossmember greater in the region of a sensor holder than the bead sections next to the sensor holder. Such an embossment in the height of the bead works to increase the stiffness.

In order to keep the distance from the outer cladding shell of the bumper crossmember to a bumper on which it is equipped low, the cladding shell preferably carries sensors which are equipped with a connector arranged in a radial direction or an electrical connection cable leading out of the sensor in this direction. The design of a bumper with such sensors is also advisable taking into consideration that not only can the length of the electrical connection cable be reduced since a cable loop is not required, but also that damage to the connection cable in the region of a cable loop on the edges of the through-holes, as can sometimes occur in bumpers according to the prior art, is prevented.

It is preferable, in the bumper according to the present disclosure, for the at least one sensor to be carried by the outer cladding shell. This is advantageous because the bumper with its bumper crossmember and the design of the at least one sensor holder can then be dimensioned such that the sensor engages or dips into a sensor holder without contacting it. The sensor does not necessarily need to be mechanically supported on the bumper crossmember, although this is possible. Without a mechanical support, vibration decoupling is effected. Impacts which act on the outer cladding shell can then also be absorbed without damaging the sensor, at least with regard to the possible crumple space of the cladding shell against the outer shell of the bumper crossmember to the extent that the sensor is distanced from the base or the walls of the sensor holder. The same applies for impacts which act non-horizontally on the outer cladding shell to which the cladding shell reacts flexibly. As a result of the distancing of the outer shell surface of the sensor from the upper wall and the lower wall and, where applicable, the side walls as envisaged in an embodiment with side walls, the sensor can also follow the cladding shell in movements relating to this without damage. The distancing of the termination of the sensor opposite the sensor head from the base of the sensor holder is typically a few millimeters to approx. 15 millimeters. This distance may also be greater depending on the available installation space. If the bumper is to have the shortest possible length in the x direction of the vehicle, the sensor holder is designed adapted to the sensor such that the sensor engages 60%-80% with its extension pointing in the longitudinal direction of the vehicle in the sensor holder in the longitudinal direction of the vehicle (x direction).

The directions used herein—x direction, y direction and z direction—are the usual directions used in a vehicle, wherein the x direction is the direction of the vehicle in its longitudinal extension, the y direction is the transverse direction to the longitudinal direction and the z direction is the height of the vehicle.

