Pedestrian Protection bumper system
Publication Date: 2005-Jul-08
The IP.com Prior Art Database
A bumper assembly comprises a cover and an undertray which are arranged and tuned to absorb energy at differing rates throughout an impact.
Pedestrian protection bumper system
It is described below a bumper system which enables to reduce injury to a pedestrian in case of the latter is hit by a vehicle.
The bumper system comprises a cover (Fig. 1) and an undertray (Figs.2 and 3) which are arranged and tuned to absorb energy at differing rates throughout the impact.
Figure 1: Plot showing the variation in cover thickness.
Fixings to Vertical columns on Cover features
Fixings to Lower section of Cover to form box-section
Figure 2: Plot showing flap feature and rib pattern on the Undertray.
Cover vertical columns to Undertray
Figure 3: Plot showing some of the key features on Undertray.
The Cover and the undertray are advantageously assembled as shown in Figs. 4 and 5.
Flap features to control intrusions Cover to Undertray attachments that box- section
Lateral hoop reinforcement generated by box section
Undertray to Cover
Section Offset fixings to equalise stiffness Figure 4: Section plot showing box section formed by Cover and Undertray.
Cover Column to Undertray fixing
Optimised stiffening ribs for load transfer to Subframe
Figure 5: Section plot showing the Undertray to Cover Column attachment.
It is described below how such a bumper system will react during an impact.
1st Phase of impact
Initially, the Top, middle and bottom region of the bumper have been tuned to absorb the Legform impact at the same rate and the axis of the Legform impactor remains vertical, thereby maximising the absorption of energy. The vertical columns on the Cover that tie the undertray to the middle section, are particularly important in controlling the energy absorption during this phase.
After the Legform has intruded a specific distance, the Bottom region (consisting of the Undertray and Cover components) starts to stiffen relative to the others, and thereby initiates a rotation in the Legform about the lateral axis.
The point at which the Legform starts to rotate is controlled by the following design features:
* The relative height of the Undertray to Legform Lower Tibia's centre of gravity.
* The box section formed by the overlay and offset of the Cover and Undertray through the critical region for Legform impact
* The optimised rib pattern on the Undertray
* The number, pitch and location of fixings between the Cover and Undertray
* Varying local thicknesses of components in this region
* The flap feature on the Undertray to assist in controlling Legform intrusion by providing additional stiffness and by limiting the Bumper Cover movement in the Bottom region.
2nd Phase of impact
During the next phase of the impact, the Legform rotation is encouraged by the foll...