Bumper energy absorber with sensor and configured lobes
A vehicle bumper system comprises a bumper reinforcement beam and an energy absorber with top and bottom rows of similarly-shaped spaced-apart crush lobes in alternating relation for uniform impact resistance across the bumper system. The illustrated top row of crush lobes provides a high first force-deflection curve for high impact forces, and the bottom row of crush lobes provides a lower second force-deflection curve, for pedestrian reduced injury. An elongated sensor is positioned under shear walls of the top and bottom crush lobes, and is retained by tabs on the energy absorber. This positively retains the sensor in position on the bumper system, with few (or zero) separate fasteners, while facilitating quick assembly and reliable operation of the sensor tube.
1. A bumper system comprising:
a bumper reinforcement beam having a face surface; and
an energy absorber having a base flange engaging the face surface, and having forwardly-extending top and bottom rows of spaced-apart crush lobes, the top row of crush lobes providing a higher first force-deflection curve upon impact that is designed for barrier bumper impact testing, and the bottom row of crush lobes providing a lower second force-deflection curve upon impact designed for minimizing injury to a pedestrian based on FLEX PLI pedestrian-leg-injury-simulating impact testing.
2. The bumper system defined in claim 1 , wherein centerlines of the crush lobes in the top row pass vertically between the crush lobes in the bottom row.
3. An energy absorber apparatus adapted for a bumper system having a bumper reinforcement beam, the apparatus comprising:
an energy absorber including a base flange adapted to engage the reinforcement beam and having forwardly-extending top and bottom rows of crush lobes, each crush lobe having shear walls; and
an elongated sensor positioned at least partially between several of the crush lobes in a position where an impact will drive some of the shear walls into the sensor.
4. A bumper system comprising:
a bumper reinforcement beam having a face surface; and
an energy absorber having a base flange engaging the face surface, and having forwardly-extending top and bottom rows of crush lobes with the crush lobes being in non-vertically aligned positions, each crush lobe having shear walls; and
an elongated sensor positioned partially under the energy absorber against the face surface.
5. The bumper system defined in claim 4 , wherein the base flange defines a horizontal channel receiving the sensor.
6. A bumper system comprising:
a bumper reinforcement beam having a face surface;
an energy absorber having a base flange engaging the face surface, and having at least one forwardly-extending row of similarly-shaped spaced-apart crush lobes; and
a horizontally-extending sensor secured to the energy absorber to retain the sensor in position on the bumper system in a position where an impact will drive some of the shear walls into the sensor.
7. The bumper system defined in claim 6 , wherein the energy absorber includes integrally-formed structure attaching the sensor to the energy absorber.
8. The bumper system defined in claim 7 , wherein the sensor comprises a tubular sensor.
9. The bumper system defined in claim 8 , wherein the integrally-formed structure includes attachment tabs on the energy absorber.
10. A bumper system comprising:
a bumper reinforcement beam having a face surface; and
an energy absorber having a base flange engaging the face surface, and having at least one forwardly-extending row of similarly-shaped spaced-apart crush lobes, each crush lobe having a plurality of shear walls that form a geometric shape with a face wall that closes a forward end of each crush lobe, the shear walls all including stiff wall structure of first wall thickness and at least some shear walls also including a soft wall structure formed by thinned material thickness that is thinner than the first wall thickness and that causes a lower force of resistance during an initial impact stroke; and
a sensor located on the energy absorber in a position where an impact will drive some of the shear walls toward the sensor.
11. The bumper system of claim 10 , wherein the sensor includes a sensor tube attached longitudinally to the energy absorber in a position where energy from a low impact occurrence is absorbed by the soft wall structure and energy from a high impact occurrence causes the stiff wall structure to engage the sensor tube and send a signal representing a high impact occurrence.
12. A bumper system comprising:
a bumper reinforcement beam having a face surface; and
an energy absorber having a base flange engaging the face surface, and having forwardly-extending top and bottom rows of similarly-shaped spaced-apart crush lobes; and
an apron extending horizontally and spaced below the beam;
the beam and top row of crush lobes combining to define a high first force-deflection curve that upon impact by a barrier bumper impact tester provides energy absorption to pass barrier bumper impact testing;
the bottom row of crush lobes and apron combining to define a lower second force-deflection curve that upon impact against a FLEX PLI pedestrian-leg-injury-simulating impact testing device provides a lower second force-deflection curve that provides reduced leg injury sufficient to pass FLEX PLI leg-injury-simulating impact testing.
13. A bumper system comprising:
a bumper reinforcement beam having a face surface; and
an energy absorber having a base flange engaging the face surface and further having forwardly-extending top and bottom rows of similarly-shaped spaced-apart crush lobes, each crush lobe having a centerline offset from the centerlines of vertically adjacent crush lobes, and each crush lobe having a vertical dimension DV and a horizontal dimension DW, with a ratio of DV:DW being less than 1.0.
14. The bumper system of claim 13 , wherein the ratio DV:DW is less than 0.5, such that when the energy absorber is in a vehicle mounted position, the crush lobe extends horizontally at least about twice a vertical dimension DV.